Carbon nitrides with two-dimensional layered structures and high theoretical capacities are attractive as anode materials for sodium-ion batteries while their low crystallinity and insufficient structural stability st...Carbon nitrides with two-dimensional layered structures and high theoretical capacities are attractive as anode materials for sodium-ion batteries while their low crystallinity and insufficient structural stability strongly restrict their practical applications.Coupling carbon nitrides with conductive carbon may relieve these issues.However,little is known about the influence of nitrogen(N)configurations on the interactions between carbon and C_(3)N_(4),which is fundamentally critical for guiding the precise design of advanced C_(3)N_(4)-related electrodes.Herein,highly crystalline C_(3)N_(4)(poly(triazine imide),PTI)based all-carbon composites were developed by molten salt strategy.More importantly,the vital role of pyrrolic-N for enhancing charge transfer and boosting Na+storage of C_(3)N_(4)-based composites,which was confirmed by both theoretical and experimental evidence,was spot-highlighted for the first time.By elaborately controlling the salt composition,the composite with high pyrrolic-N and minimized graphitic-N content was obtained.Profiting from the formation of highly crystalline PTI and electrochemically favorable pyrrolic-N configurations,the composite delivered an unusual reverse growth and record-level cycling stability even after 5000 cycles along with high reversible capacity and outstanding full-cell capacity retention.This work broadens the energy storage applications of C_(3)N_(4) and provides new prospects for the design of advanced all-carbon electrodes.展开更多
Chitin is the second most abundant renewable polysaccharide on Earth.The degradation of chitin into soluble and bioactive N-acetyl chitooligosaccharides(NCOSs)and N-acetyl-D-glucosamine(GlcNAc)has emerged as a pivotal...Chitin is the second most abundant renewable polysaccharide on Earth.The degradation of chitin into soluble and bioactive N-acetyl chitooligosaccharides(NCOSs)and N-acetyl-D-glucosamine(GlcNAc)has emerged as a pivotal step in the efficient and sustainable utilization of chitin resources.However,because of its dense structure,high crystallinity,and poor solubility,chitin typically needs pretreatment via chemical,physical,and other methods before enzymatic conversion to enhance the accessibility between substrates and enzyme molecules.Consequently,there has been considerable interest in exploring the direct biological degradation of crystalline chitin as a cost-effective and environment-friendly technology.This review endeavors to present several biological methods for the direct degradation of chitin.We primarily focused on the importance of chitinase containing chitin-binding domain(CBD).Additionally,various modification strategies for increasing the degradation efficiency of crystalline chitin were introduced.Subsequently,the review systematically elucidated critical components of multi-enzyme catalytic systems,highlighting their potential for chitin degradation.Furthermore,the application of microorganisms in the degradation of crystalline chitin was also discussed.The insights in this review contribute to the explorations and investigations of enzymatic and microbial approaches for the direct degradation of crystalline chitin,thereby fostering advancements in biomass conversion.展开更多
Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall phy...Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall physical responses,and reactions in a-1,3,5-trinitro-1,3,5-triazinane(a-RDX)crystal entrained various chemical inclusions were investigated by the multi-scale shock technique implemented in the reactive molecular dynamics method.Results indicated that energy localization and shock reaction were affected by the intrinsic factors within chemical inclusions,i.e.,phase states,chemical compositions,and concentrations.The atomic origin of chemical-inclusions effects on energy localization is dependent on the dynamics mechanism of interfacial molecules with free space volume,which includes homogeneous intermolecular compression,interfacial impact and shear,and void collapse and jet.As introducing various chemical inclusions,the initiation of those dynamics mechanisms triggers diverse decay rates of bulk RDX molecules and hereby impacts on growth speeds of final reactions.Adding chemical inclusions can reduce the effectiveness of the void during the shock impacting.Under the shockwave velocity of 9 km/s,the parent RDX decay rate in RDX entrained amorphous carbon decreases the most and is about one fourth of that in RDX with a vacuum void,and solid HMX and TATB inclusions are more reactive than amorphous carbon but less reactive than dry air or acetone inclusions.The lessdense shocking system denotes the greater increases in local temperature and stress,the faster energy liberation,and the earlier final reaction into equilibrium,revealing more pronounced responses to the present intense shockwave.The quantitative models associated with the relative system density(RD_(sys))were proposed for indicating energy-localization mechanisms and evaluating initiation safety in the shocked crystalline explosive.RD_(sys)is defined by the density ratio of defective RDX to perfect crystal after dynamics relaxation and reveals the global density characteristic in shocked systems filled with chemical inclusions.When RD_(sys)is below 0.9,local hydrodynamic jet initiated by void collapse dominates upon energy localization instead of interfacial impact.This study sheds light on novel insights for understanding the shock chemistry and physical-based atomic origin in crystalline explosives considering chemical-inclusions effects.展开更多
In this paper,high-energy Ne ions were used to irradiate Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) metallic glass(MG)and crystalline W to investigate their difference in mechanical response after irradiation.The results showed t...In this paper,high-energy Ne ions were used to irradiate Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) metallic glass(MG)and crystalline W to investigate their difference in mechanical response after irradiation.The results showed that with the irradiation dose increased,the tensile micro-strain increased,nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa,Young’s modulus increased,and H3/E2 increased which indicating that the plastic deformability decreased in crystalline W.Under the same irradiation conditions,the Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG than in crystalline W.Unlike the irradiation hardening and embrittlement behavior of crystalline W,Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa,the decrease in modulus and the increase in plastic deformability with the increasing dose.Possibly,the irradiation softening and toughening phenomenon of Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG could provide new ideas for the design of nuclear materials.展开更多
The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the...The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the strength.However,most strength criteria neglect the strength variations caused by different grain characteristics in rocks.Furthermore,the traditional linear criteria tend to overestimate tensile strength and exhibit apex singularity.To address these shortcomings,a piecewise strength criterion that considers the grain size effect has been proposed.A part of an ellipse was employed to construct the envelope of the tensive-shear region on the meridian plane,to accurately reproduce the low tensile-compressive strength ratio.Based on the analysis of experimental data,both linear and exponential modification functions that account for grain size effects were integrated into the proposed criterion.The corresponding finite element algorithm has been implemented.The accuracy and applicability of the proposed criterion were validated by comparing with the experimental data.展开更多
The practical application of lithium(Li)metal anodes in high-capacity batteries is impeded by the formation of hazardous Li dendrites.To address this challenge,this research presents a novel methodology that combines ...The practical application of lithium(Li)metal anodes in high-capacity batteries is impeded by the formation of hazardous Li dendrites.To address this challenge,this research presents a novel methodology that combines laser ablation and heat treatment to precisely induce controlled grain growth within laser-structured grooves on copper(Cu)current collectors.Specifically,this approach enhances the prevalence of Cu(100)facets within the grooves,effectively lowering the overpotential for Li nucleation and promoting preferential Li deposition.Unlike approaches that modify the entire surface of collectors,our work focuses on selectively enhancing lithiophilicity within the grooves to mitigate the formation of Li dendrites and exhibit exceptional performance metrics.The half-cell with these collectors maintains a remarkable Coulombic efficiency of 97.42%over 350 cycles at 1 mA cm^(−2).The symmetric cell can cycle stably for 1600 h at 0.5 mA cm^(−2).Furthermore,when integrated with LiFePO4 cathodes,the full-cell configuration demonstrates outstanding capacity retention of 92.39%after 400 cycles at a 1C discharge rate.This study introduces a novel technique for fabricating selective lithiophilic three-dimensional(3D)Cu current collectors,thereby enhancing the performance of Li metal batteries.The insights gained from this approach hold promise for enhancing the performance of all laser-processed 3D Cu current collectors by enabling precise lithiophilic modifications within complex structures.展开更多
An innovative microcrystalline cellulose(MCC)natural fibre powder-reinforced PLA biocomposite was investigated using the hand lay-up technique.The polymer matrix composite(PMC)samples were prepared by varying the weig...An innovative microcrystalline cellulose(MCC)natural fibre powder-reinforced PLA biocomposite was investigated using the hand lay-up technique.The polymer matrix composite(PMC)samples were prepared by varying the weight percentages(wt.%)of both PLA matrix and MCC reinforcement:pure PLA/100:0,90:10,80:20,70:30,60:40 and 50:50 wt.%,respectively.From the results obtained,MCC powder,with its impressive aspect ratio,proved to be an ideal reinforcement for the PLA,exhibiting exceptional mechanical properties.It was evident that the 80:20 wt.%biocomposite sample exhibited the maximum improvement in the tensile,flexural,notched impact,compressive strength and hardness by 28.85%,20.00%,91.66%,21.53%and 35.82%,respectively compared to the pure PLA sample.Similarly,during the thermogravimetric analysis(TGA),the same 80:20 wt.%biocomposite sample showed a minimum weight loss of 20%at 400℃,among others.The morphological study using Field Emission Scanning Electron Microscopy(FE-SEM)revealed that the uniform distribution of cellulose reinforcement in the PLA matrix actively improved the mechanical properties of the biocomposites,especially the optimal 80:20 wt.%sample.Importantly,it was evident that the optimal PLA/cellulose biocomposite sample could be a suitable and alternative sustainable,environmentally friendly and biodegradable material for semi/structural applications,replacing synthetic and traditional components.展开更多
By including certain point group symmetry in the classification of band topology,Fu proposed a class of threedimensionaltopological crystalline insulators(TCIs)without spin-orbit coupling in 2011.In Fu’s model,surfac...By including certain point group symmetry in the classification of band topology,Fu proposed a class of threedimensionaltopological crystalline insulators(TCIs)without spin-orbit coupling in 2011.In Fu’s model,surface states(ifpresent)doubly degenerate atГandM when time-reversal and C_(4) symmetries are preserved.The analogs of Fu’s modelwith surface states quadratically degenerate atM are widely studied,while surface states with quadratic degeneracy atГare rarely reported.In this study,we propose a three-dimensional TCI without spin-orbit coupling in a judiciously designednonsymmorphic photonic metacrystal.The surface states of photonic TCIs exhibit quadratic band degeneracy in the(001)surface Brillouin zone(BZ)center(Гpoint).The gapless surface states and their quadratic dispersion are protected by C4and time-reversal symmetries,which correspond to the nontrivial band topology characterized by Z_(2)topological invariant.Moreover,the surface states along lines fromГto the(001)surface BZ boundary exhibit zigzag feature,which is interpretedfrom symmetry perspective by building composite operators constructed by the product of glide symmetries with timereversalsymmetry.The metacrystal array surrounded with air possesses high order hinge states with electric fields highlylocalized at the hinge that may apply to optical sensors.The gapless surface states and hinge states reside in a cleanfrequency bandgap.The topological surface states emerge at the boundary of the metacrystal and perfect electric conductor(PEC),which provide a pathway for topologically manipulating light propagation in photonic devices.展开更多
For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quanti...For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quantities as normal melting temperature, surface tension, molar volume and critical molar volume is received on the base of the principle of corresponding states and the energy equipartition theorem. Moreover, the proposed equation allows one to take into account the particularities of one-particle molecular rotation in the plastic crystalline phase.展开更多
Cementitious capillary crystalline waterproof materials(CCCW for short)offer durability and excellent waterproofing properties,making them a popular option for building waterproofing.Some scholars have studied the pro...Cementitious capillary crystalline waterproof materials(CCCW for short)offer durability and excellent waterproofing properties,making them a popular option for building waterproofing.Some scholars have studied the proportioning of such materials.However,these studies lack the relationship between the impermeability pressure of mortar and the components,and the mechanism of action is somewhat debatable.Therefore,we adopted a two-step method in our experiments.Firstly,we screened out the components that significantly impact impermeability from a variety of active components by orthogonal test.We then optimized the design of the active group ratio using the simplex lattice method.Lastly,we conducted a performance test of the optimal ratio and explored the waterproofing mechanism of homemade CCCW.展开更多
In widely studied organic-inorganic hybrid perovskites,the organic component tends to volatilize and decompose under high temperatures,oxygen,and humidity,which adversely affects the performance and longevity of the a...In widely studied organic-inorganic hybrid perovskites,the organic component tends to volatilize and decompose under high temperatures,oxygen,and humidity,which adversely affects the performance and longevity of the associated solar cells.In contrast,all-inorganic perovskites demonstrate superior stability under these conditions and offer photoelectric properties comparable to those of their hybrid counterparts.The potential of tandem solar cells(TSCs)made from all-inorganic perovskites is especially promising.This review is the first to address recent advancements in TSCs that use all-inorganic perovskites and crystalline silicon(c-Si),both domestically and internationally.This work provides a systematic and thorough analysis of the current challenges faced by these systems and proposes rational solutions.Additionally,we elucidate the regulatory mechanisms of all-inorganic perovskites and their TSCs when combined with c-Si,summarizing the corresponding patterns.Finally,we outline future research directions for all-inorganic perovskites and their TSCs with c-Si.This work offers valuable insights and references for the continued advancement of perovskitebased TSCs.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applicat...Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applications.Currently,synthesizing highly crystalline g-C_(3)N_(4) with sufficient surface activities still remains challenging.Herein,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed salts.The rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for re-condensation.Intriguingly,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt methods.These catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.展开更多
By means of X ray and gas chromatography analysis, the crystalline structure of untreated wood , alkali treated wood and benzylated wood and their liquefaction in toluene and tetrahydrofufan with HCl as a catalyst we...By means of X ray and gas chromatography analysis, the crystalline structure of untreated wood , alkali treated wood and benzylated wood and their liquefaction in toluene and tetrahydrofufan with HCl as a catalyst were studied .The upper solution of benzylated wood was also studied by GC MS analysis. It proved that the introduction of bulky benzyl group in wood significantly changed the crystalline structure of wood ,enlarging the free volume which facilitated the penetration of solvent into the matrix of treated wood, thus tremendously enhancing thesolubility in solvent,compared to untreated wood and alkali treated wood. The percentage of residue decreased and the combined solvent increased with the increase of weight gain revealed that the liquefaction process became easy. Furthermore, the factors that influenced the liquefaction of benzylated wood were investigated. It showed that the liquefaction performance was improved with the increase of liquefaction time and the amount of catalyst when toluene was used as a solvent, especially in the presence of THF as solvent, there existed the optimum liquefaction time and the amount of catalyst .展开更多
Under a given condition of crystallization, dark brown short rhombohedron crystals could be obtained from Δ nifZ MoFe protein purified from a nifZ deleted mutant strain of Azotobacter vinelandii Lipmann....Under a given condition of crystallization, dark brown short rhombohedron crystals could be obtained from Δ nifZ MoFe protein purified from a nifZ deleted mutant strain of Azotobacter vinelandii Lipmann. Systematic studies on the effect of concentrations of PEG 8000,MgCl 2, NaCl,Tris and buffer pH on the crystallization and crystal growth of the protein showed that the protein could not be crystallized in lower concentrations of the chemicals and lower buffer pH. A large amount of smaller crystals of the protein appeared in a week with gradual increasing in the chemical concentrations and pH≥8.0. When the chemical concentrations were further increased, the time for crystallization was increased and a few high grade crystals of larger size were formed. If the concentrations of the chemicals were continuously increased, many crystals with smaller size, and, sometimes of poor quality appeared again and eventually ceased to produce any crystals. The optimal concentration for each of the above mentioned chemicals varies with other variable factors. Only one bigger crystal (both of the longest two sides: 0.16 mm) could be obtained in a hanging drop of protein sample when the concentrations of PEG 8000, MgCl 2, NaCl,Tris and protein were kept at 1.86%, 300 mmol/L, 400 mmol/L, 53 mmol/L and 4.64 g/L , respectively, with Tris buffer pH 8.2.展开更多
<strong>Objective:</strong> For materials science and generally, for long-term operation of work-pieces in industry the significant role is attributed to dependence of macro-mechanical properties of consol...<strong>Objective:</strong> For materials science and generally, for long-term operation of work-pieces in industry the significant role is attributed to dependence of macro-mechanical properties of consolidated body on crystalline phase composition, its dimensions, form, distribution in matrix and the form factor. While working in responsible fields of technology of ceramics and ceramic composites the above referred properties are attributed extremely great role with the view of durability and endurance at the terms of heavy mechanical loads. For description of the resistance of any concrete type work-piece, the crystalline phase plays the greatest role in mechanical strength or deformation of any material. It plays the important role in correlative explanation of materials mechanics and matrix properties. In our case, in the process of destruction of ceramic materials and composites, which will give us exhaustive response to the role of macro- and micro-mechanical properties of materials, the role of a macro- and micro-structural component, that is, of crystalline phase in the process of transition of stable state of materials into meta-stable state is extremely big. Our study aims to develop a formula of dependence of macro-mechanical properties of ceramic and ceramic composites on crystalline phase, the most powerful component of their structure, which will enable theorists and practitioners to select and develop technologies and technological processes correctly. <strong>Method:</strong> On the basis of the study of micro- and macro-mechanical properties of ceramics and ceramic composites and the morphology of crystalline phase and the analysis of the study we determined and created parameters of the formula. <strong>Results:</strong> The formula covers macro-mechanical properties, that is when the work-piece is thoroughly destructed: mechanic at bending at three and four-point load, mechanic at contraction;among morphological characteristics: composition of crystalline phase and their spreading in matrix, their sizes, form factor;correlative dependence of the above listed properties. Absolutely new definition of a factor of spreading of crystalline phase in matrix is offered. <strong>Conclusion: </strong>The created formula is of consolidated nature and it can be used in technology of any ceramic material and ceramic composites. The formula will help practitioners to plan correctly and fulfill accurately all positions of technology of production of work-pieces, to carry out the most responsible thermal treatment process of technology of manufacture of work-pieces;to determine correlation between mechanical and matrix properties of materials.展开更多
A new type of liquid crystalline polyesters with resorcin as one part of the mesogenic unitconnected together by polymethylene, or phenylene group, and lateral groups consisting of arigid azobenzene as another part of...A new type of liquid crystalline polyesters with resorcin as one part of the mesogenic unitconnected together by polymethylene, or phenylene group, and lateral groups consisting of arigid azobenzene as another part of the mesogenic unit were synthesized by interfacialpolymerization of diacyl chlorides in 1, 2-dichloroethane and 2, 4-dihydroxy-4'-nitroazobenzen inaqueous alkaline solution. The polyester structures were confirmed by proton NMR and IRspectra. Their phase transition behavior and texture were studied by polarizing microscopy andDSC.展开更多
A much larger amount of bonded hydrogen was found in thick nanocrystalline diamond (NCD) films produced by only adding 0.24% N2 into 4% CH4/H2 plasma, as compared to the high quality transparent microcrystalline dia...A much larger amount of bonded hydrogen was found in thick nanocrystalline diamond (NCD) films produced by only adding 0.24% N2 into 4% CH4/H2 plasma, as compared to the high quality transparent microcrystalline diamond (MCD) films, grown using the same growth parameters except for nitrogen. These experimental results clearly evidence that defect formation and impurity incorporation (for example, N and H) impeding diamond grain growth is the main formation mechanism of NCD upon nitrogen doping and strongly support the model proposed in the literature that nitrogen competes with CHx (x = 1, 2, 3) growth species for adsorption sites.展开更多
MCC (micro crystalline cellulose) is a very important product in pharmaceuticals, foods, cosmetics and other industries. MCC can be made from any natural cellulose materials that have high content of cellulose rangi...MCC (micro crystalline cellulose) is a very important product in pharmaceuticals, foods, cosmetics and other industries. MCC can be made from any natural cellulose materials that have high content of cellulose ranging from pure cellulose, commercial grade cellulose to lignocellulosic materials. In this work, Beeswing (-20 L) and Chaff (5/8) which are the parts of corn cobs were used as raw materials to produce MCC via alkaline degradation, bleaching and hydrolysis. The optimum conditions of alkaline degradation, bleaching and hydrolysis were studied. MCC samples that prepared from -20 L and 5/8 were characterized through XRD (X-ray diffraction), SEM (scanning electron microscopy) and compared with the commercial MCC (Avicel PH 101). The results show that the degree of crystallinity of alkaline degradation, bleaching and hydrolysis obtained at 10% of NaOH 95 ~C for 2 h, NaCIO21.5 g 10% of acetic acid 0.5 mL 70 ~C for 2 h, 2 N of HC1, 105 ~C for 1 h showed maximum values which are 77.07%, 75.07% and 86.84%, respectively. The degree of crystallinity and the morphology of prepared MCC correspond to that of Avicel PH 101 industrial investment has been studied, the benefits of micro crystalline cellulose production (MCC) is 3,447 baht/kg. The investment of the plant is 7,263,514 baht and the breakeven point is around 6 years.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))has emerged as a remarkably promising photocatalyst for addressing environmental and energy issues;however,it exhibits only moderate photocatalytic activity because of its low spe...Graphitic carbon nitride(g-C_(3)N_(4))has emerged as a remarkably promising photocatalyst for addressing environmental and energy issues;however,it exhibits only moderate photocatalytic activity because of its low specific surface area and high recombination of carriers.Preparation of crystalline g-C_(3)N_(4) by the molten salt method has proven to be an effective method to improve the photocatalytic activity.However,crystalline g-C_(3)N_(4) prepared by the conventional molten salt method exhibits a less regular morphology.Herein,highly crystalline g-C_(3)N_(4) hollow spheres(CCNHS)were successfully prepared by the molten salt method using cyanuric acid-melamine as a precursor.The higher crystallization of the CCNHS samples not only repaired the structural defects at the surface of the CCNHS samples but also established a built-in electric field between heptazine-based g-C_(3)N_(4) and triazine-based g-C_(3)N_(4).The hollow structure improved the level of light energy utilization and increased the number of active sites for photocatalytic reactions.Because of the above characteristics,the as-prepared CCNHS samples simultaneously realized photocatalytic hydrogen evolution with the degradation of the plasticizer bisphenol A.This research offers a new perspective on the structural optimization of supramolecular self-assembly.展开更多
Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomi...Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.展开更多
基金supported by the National Natural Science Foundation of China(51904059)Applied Basic Research Program of Liaoning(2022JH2/101300200)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2022A1515140188)Fundamental Research Funds for the Central Universities(N_(2)002005,N_(2)125004,N_(2)225044)。
文摘Carbon nitrides with two-dimensional layered structures and high theoretical capacities are attractive as anode materials for sodium-ion batteries while their low crystallinity and insufficient structural stability strongly restrict their practical applications.Coupling carbon nitrides with conductive carbon may relieve these issues.However,little is known about the influence of nitrogen(N)configurations on the interactions between carbon and C_(3)N_(4),which is fundamentally critical for guiding the precise design of advanced C_(3)N_(4)-related electrodes.Herein,highly crystalline C_(3)N_(4)(poly(triazine imide),PTI)based all-carbon composites were developed by molten salt strategy.More importantly,the vital role of pyrrolic-N for enhancing charge transfer and boosting Na+storage of C_(3)N_(4)-based composites,which was confirmed by both theoretical and experimental evidence,was spot-highlighted for the first time.By elaborately controlling the salt composition,the composite with high pyrrolic-N and minimized graphitic-N content was obtained.Profiting from the formation of highly crystalline PTI and electrochemically favorable pyrrolic-N configurations,the composite delivered an unusual reverse growth and record-level cycling stability even after 5000 cycles along with high reversible capacity and outstanding full-cell capacity retention.This work broadens the energy storage applications of C_(3)N_(4) and provides new prospects for the design of advanced all-carbon electrodes.
基金supported by the National Key Research and Development Program of China(No.2023YFD2401504)the National Natural Science Foundation of China(Nos.U21A20271,32225039)+2 种基金the Key R&D Program of Shandong Province(No.2022TZXD001)the Earmarked Fund for CARS(No.CARS-48)the Qingdao Shinan District Science and Technology Plan Project(No.2022-3-010-SW).
文摘Chitin is the second most abundant renewable polysaccharide on Earth.The degradation of chitin into soluble and bioactive N-acetyl chitooligosaccharides(NCOSs)and N-acetyl-D-glucosamine(GlcNAc)has emerged as a pivotal step in the efficient and sustainable utilization of chitin resources.However,because of its dense structure,high crystallinity,and poor solubility,chitin typically needs pretreatment via chemical,physical,and other methods before enzymatic conversion to enhance the accessibility between substrates and enzyme molecules.Consequently,there has been considerable interest in exploring the direct biological degradation of crystalline chitin as a cost-effective and environment-friendly technology.This review endeavors to present several biological methods for the direct degradation of chitin.We primarily focused on the importance of chitinase containing chitin-binding domain(CBD).Additionally,various modification strategies for increasing the degradation efficiency of crystalline chitin were introduced.Subsequently,the review systematically elucidated critical components of multi-enzyme catalytic systems,highlighting their potential for chitin degradation.Furthermore,the application of microorganisms in the degradation of crystalline chitin was also discussed.The insights in this review contribute to the explorations and investigations of enzymatic and microbial approaches for the direct degradation of crystalline chitin,thereby fostering advancements in biomass conversion.
基金the financial support from National Natural Science Foundation of China(Grant Nos.11872119,12172051,and 11972329)Natural Science Foundation of Hubei Province(Grant No.2021CFB120)。
文摘Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall physical responses,and reactions in a-1,3,5-trinitro-1,3,5-triazinane(a-RDX)crystal entrained various chemical inclusions were investigated by the multi-scale shock technique implemented in the reactive molecular dynamics method.Results indicated that energy localization and shock reaction were affected by the intrinsic factors within chemical inclusions,i.e.,phase states,chemical compositions,and concentrations.The atomic origin of chemical-inclusions effects on energy localization is dependent on the dynamics mechanism of interfacial molecules with free space volume,which includes homogeneous intermolecular compression,interfacial impact and shear,and void collapse and jet.As introducing various chemical inclusions,the initiation of those dynamics mechanisms triggers diverse decay rates of bulk RDX molecules and hereby impacts on growth speeds of final reactions.Adding chemical inclusions can reduce the effectiveness of the void during the shock impacting.Under the shockwave velocity of 9 km/s,the parent RDX decay rate in RDX entrained amorphous carbon decreases the most and is about one fourth of that in RDX with a vacuum void,and solid HMX and TATB inclusions are more reactive than amorphous carbon but less reactive than dry air or acetone inclusions.The lessdense shocking system denotes the greater increases in local temperature and stress,the faster energy liberation,and the earlier final reaction into equilibrium,revealing more pronounced responses to the present intense shockwave.The quantitative models associated with the relative system density(RD_(sys))were proposed for indicating energy-localization mechanisms and evaluating initiation safety in the shocked crystalline explosive.RD_(sys)is defined by the density ratio of defective RDX to perfect crystal after dynamics relaxation and reveals the global density characteristic in shocked systems filled with chemical inclusions.When RD_(sys)is below 0.9,local hydrodynamic jet initiated by void collapse dominates upon energy localization instead of interfacial impact.This study sheds light on novel insights for understanding the shock chemistry and physical-based atomic origin in crystalline explosives considering chemical-inclusions effects.
基金supported by National Natural Science Foundation of China(Nos.12305224,U23B2099 and 11975065)the Natural Science Foundation of Liaoning Province(No.2021-BS-223)+1 种基金the Liaoning Provincial Department of Education Youth Fund Project(No.LJKQZ20222309)supports from the National Laboratory of Heavy-ion Research Facility(HIRFL)in the Institute of Modern Physics in Lanzhou,China.
文摘In this paper,high-energy Ne ions were used to irradiate Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) metallic glass(MG)and crystalline W to investigate their difference in mechanical response after irradiation.The results showed that with the irradiation dose increased,the tensile micro-strain increased,nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa,Young’s modulus increased,and H3/E2 increased which indicating that the plastic deformability decreased in crystalline W.Under the same irradiation conditions,the Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG than in crystalline W.Unlike the irradiation hardening and embrittlement behavior of crystalline W,Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa,the decrease in modulus and the increase in plastic deformability with the increasing dose.Possibly,the irradiation softening and toughening phenomenon of Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG could provide new ideas for the design of nuclear materials.
基金Project(2023YFC2907403)supported by the National Key R&D Program of ChinaProject(52074021)supported by the National Natural Science Foundation of China+1 种基金Project(2242045)supported by Beijing Natural Science Foundation,ChinaProject(ZD202216)supported by the Beijing Association of Higher Education,China。
文摘The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the strength.However,most strength criteria neglect the strength variations caused by different grain characteristics in rocks.Furthermore,the traditional linear criteria tend to overestimate tensile strength and exhibit apex singularity.To address these shortcomings,a piecewise strength criterion that considers the grain size effect has been proposed.A part of an ellipse was employed to construct the envelope of the tensive-shear region on the meridian plane,to accurately reproduce the low tensile-compressive strength ratio.Based on the analysis of experimental data,both linear and exponential modification functions that account for grain size effects were integrated into the proposed criterion.The corresponding finite element algorithm has been implemented.The accuracy and applicability of the proposed criterion were validated by comparing with the experimental data.
基金supported by the National Natural Science Foundation of China(Grant No.52375438)Shenzhen Science and Technology Programs(Grant No.JCYJ20220818100408019,JSGG20220831101401003,JSGG20210802154007021,KQTD201708101102503570).
文摘The practical application of lithium(Li)metal anodes in high-capacity batteries is impeded by the formation of hazardous Li dendrites.To address this challenge,this research presents a novel methodology that combines laser ablation and heat treatment to precisely induce controlled grain growth within laser-structured grooves on copper(Cu)current collectors.Specifically,this approach enhances the prevalence of Cu(100)facets within the grooves,effectively lowering the overpotential for Li nucleation and promoting preferential Li deposition.Unlike approaches that modify the entire surface of collectors,our work focuses on selectively enhancing lithiophilicity within the grooves to mitigate the formation of Li dendrites and exhibit exceptional performance metrics.The half-cell with these collectors maintains a remarkable Coulombic efficiency of 97.42%over 350 cycles at 1 mA cm^(−2).The symmetric cell can cycle stably for 1600 h at 0.5 mA cm^(−2).Furthermore,when integrated with LiFePO4 cathodes,the full-cell configuration demonstrates outstanding capacity retention of 92.39%after 400 cycles at a 1C discharge rate.This study introduces a novel technique for fabricating selective lithiophilic three-dimensional(3D)Cu current collectors,thereby enhancing the performance of Li metal batteries.The insights gained from this approach hold promise for enhancing the performance of all laser-processed 3D Cu current collectors by enabling precise lithiophilic modifications within complex structures.
基金funding from Researchers Supporting Project Number(RSP2024R355),King Saud University,Riyadh,Saudi Arabia.
文摘An innovative microcrystalline cellulose(MCC)natural fibre powder-reinforced PLA biocomposite was investigated using the hand lay-up technique.The polymer matrix composite(PMC)samples were prepared by varying the weight percentages(wt.%)of both PLA matrix and MCC reinforcement:pure PLA/100:0,90:10,80:20,70:30,60:40 and 50:50 wt.%,respectively.From the results obtained,MCC powder,with its impressive aspect ratio,proved to be an ideal reinforcement for the PLA,exhibiting exceptional mechanical properties.It was evident that the 80:20 wt.%biocomposite sample exhibited the maximum improvement in the tensile,flexural,notched impact,compressive strength and hardness by 28.85%,20.00%,91.66%,21.53%and 35.82%,respectively compared to the pure PLA sample.Similarly,during the thermogravimetric analysis(TGA),the same 80:20 wt.%biocomposite sample showed a minimum weight loss of 20%at 400℃,among others.The morphological study using Field Emission Scanning Electron Microscopy(FE-SEM)revealed that the uniform distribution of cellulose reinforcement in the PLA matrix actively improved the mechanical properties of the biocomposites,especially the optimal 80:20 wt.%sample.Importantly,it was evident that the optimal PLA/cellulose biocomposite sample could be a suitable and alternative sustainable,environmentally friendly and biodegradable material for semi/structural applications,replacing synthetic and traditional components.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.12104148)the Fundamental Research Funds for the Central Universities(Grant No.531118010565).
文摘By including certain point group symmetry in the classification of band topology,Fu proposed a class of threedimensionaltopological crystalline insulators(TCIs)without spin-orbit coupling in 2011.In Fu’s model,surface states(ifpresent)doubly degenerate atГandM when time-reversal and C_(4) symmetries are preserved.The analogs of Fu’s modelwith surface states quadratically degenerate atM are widely studied,while surface states with quadratic degeneracy atГare rarely reported.In this study,we propose a three-dimensional TCI without spin-orbit coupling in a judiciously designednonsymmorphic photonic metacrystal.The surface states of photonic TCIs exhibit quadratic band degeneracy in the(001)surface Brillouin zone(BZ)center(Гpoint).The gapless surface states and their quadratic dispersion are protected by C4and time-reversal symmetries,which correspond to the nontrivial band topology characterized by Z_(2)topological invariant.Moreover,the surface states along lines fromГto the(001)surface BZ boundary exhibit zigzag feature,which is interpretedfrom symmetry perspective by building composite operators constructed by the product of glide symmetries with timereversalsymmetry.The metacrystal array surrounded with air possesses high order hinge states with electric fields highlylocalized at the hinge that may apply to optical sensors.The gapless surface states and hinge states reside in a cleanfrequency bandgap.The topological surface states emerge at the boundary of the metacrystal and perfect electric conductor(PEC),which provide a pathway for topologically manipulating light propagation in photonic devices.
文摘For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quantities as normal melting temperature, surface tension, molar volume and critical molar volume is received on the base of the principle of corresponding states and the energy equipartition theorem. Moreover, the proposed equation allows one to take into account the particularities of one-particle molecular rotation in the plastic crystalline phase.
文摘Cementitious capillary crystalline waterproof materials(CCCW for short)offer durability and excellent waterproofing properties,making them a popular option for building waterproofing.Some scholars have studied the proportioning of such materials.However,these studies lack the relationship between the impermeability pressure of mortar and the components,and the mechanism of action is somewhat debatable.Therefore,we adopted a two-step method in our experiments.Firstly,we screened out the components that significantly impact impermeability from a variety of active components by orthogonal test.We then optimized the design of the active group ratio using the simplex lattice method.Lastly,we conducted a performance test of the optimal ratio and explored the waterproofing mechanism of homemade CCCW.
基金the National Natural Science Foundation of China(Grant Nos.52164050 and 51762043)Major Science and Technology Project of Yunnan Province(Grant No.202202AB080010).
文摘In widely studied organic-inorganic hybrid perovskites,the organic component tends to volatilize and decompose under high temperatures,oxygen,and humidity,which adversely affects the performance and longevity of the associated solar cells.In contrast,all-inorganic perovskites demonstrate superior stability under these conditions and offer photoelectric properties comparable to those of their hybrid counterparts.The potential of tandem solar cells(TSCs)made from all-inorganic perovskites is especially promising.This review is the first to address recent advancements in TSCs that use all-inorganic perovskites and crystalline silicon(c-Si),both domestically and internationally.This work provides a systematic and thorough analysis of the current challenges faced by these systems and proposes rational solutions.Additionally,we elucidate the regulatory mechanisms of all-inorganic perovskites and their TSCs when combined with c-Si,summarizing the corresponding patterns.Finally,we outline future research directions for all-inorganic perovskites and their TSCs with c-Si.This work offers valuable insights and references for the continued advancement of perovskitebased TSCs.
基金supported by the National Natural Science Foundation of China(51902045,51904059)Fundamental Research Funds for the Central Universities(N2002005,N2125004,N2225038,N2225044)+2 种基金Applied Basic Research Program of Liaoning(2022JH2/101300200)Young Elite Scientist Sponsorship Program by CAST(YESS)2019-2021QNRCNational Research Foundation of Korea(NRF)grant funded by the Korean government(Ministry of Science,ICT&Future Planning)(NRF-2020R1F1A1075601 and NRF-2021R1A4A2001658).
文摘Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applications.Currently,synthesizing highly crystalline g-C_(3)N_(4) with sufficient surface activities still remains challenging.Herein,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed salts.The rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for re-condensation.Intriguingly,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt methods.These catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.
文摘By means of X ray and gas chromatography analysis, the crystalline structure of untreated wood , alkali treated wood and benzylated wood and their liquefaction in toluene and tetrahydrofufan with HCl as a catalyst were studied .The upper solution of benzylated wood was also studied by GC MS analysis. It proved that the introduction of bulky benzyl group in wood significantly changed the crystalline structure of wood ,enlarging the free volume which facilitated the penetration of solvent into the matrix of treated wood, thus tremendously enhancing thesolubility in solvent,compared to untreated wood and alkali treated wood. The percentage of residue decreased and the combined solvent increased with the increase of weight gain revealed that the liquefaction process became easy. Furthermore, the factors that influenced the liquefaction of benzylated wood were investigated. It showed that the liquefaction performance was improved with the increase of liquefaction time and the amount of catalyst when toluene was used as a solvent, especially in the presence of THF as solvent, there existed the optimum liquefaction time and the amount of catalyst .
文摘Under a given condition of crystallization, dark brown short rhombohedron crystals could be obtained from Δ nifZ MoFe protein purified from a nifZ deleted mutant strain of Azotobacter vinelandii Lipmann. Systematic studies on the effect of concentrations of PEG 8000,MgCl 2, NaCl,Tris and buffer pH on the crystallization and crystal growth of the protein showed that the protein could not be crystallized in lower concentrations of the chemicals and lower buffer pH. A large amount of smaller crystals of the protein appeared in a week with gradual increasing in the chemical concentrations and pH≥8.0. When the chemical concentrations were further increased, the time for crystallization was increased and a few high grade crystals of larger size were formed. If the concentrations of the chemicals were continuously increased, many crystals with smaller size, and, sometimes of poor quality appeared again and eventually ceased to produce any crystals. The optimal concentration for each of the above mentioned chemicals varies with other variable factors. Only one bigger crystal (both of the longest two sides: 0.16 mm) could be obtained in a hanging drop of protein sample when the concentrations of PEG 8000, MgCl 2, NaCl,Tris and protein were kept at 1.86%, 300 mmol/L, 400 mmol/L, 53 mmol/L and 4.64 g/L , respectively, with Tris buffer pH 8.2.
文摘<strong>Objective:</strong> For materials science and generally, for long-term operation of work-pieces in industry the significant role is attributed to dependence of macro-mechanical properties of consolidated body on crystalline phase composition, its dimensions, form, distribution in matrix and the form factor. While working in responsible fields of technology of ceramics and ceramic composites the above referred properties are attributed extremely great role with the view of durability and endurance at the terms of heavy mechanical loads. For description of the resistance of any concrete type work-piece, the crystalline phase plays the greatest role in mechanical strength or deformation of any material. It plays the important role in correlative explanation of materials mechanics and matrix properties. In our case, in the process of destruction of ceramic materials and composites, which will give us exhaustive response to the role of macro- and micro-mechanical properties of materials, the role of a macro- and micro-structural component, that is, of crystalline phase in the process of transition of stable state of materials into meta-stable state is extremely big. Our study aims to develop a formula of dependence of macro-mechanical properties of ceramic and ceramic composites on crystalline phase, the most powerful component of their structure, which will enable theorists and practitioners to select and develop technologies and technological processes correctly. <strong>Method:</strong> On the basis of the study of micro- and macro-mechanical properties of ceramics and ceramic composites and the morphology of crystalline phase and the analysis of the study we determined and created parameters of the formula. <strong>Results:</strong> The formula covers macro-mechanical properties, that is when the work-piece is thoroughly destructed: mechanic at bending at three and four-point load, mechanic at contraction;among morphological characteristics: composition of crystalline phase and their spreading in matrix, their sizes, form factor;correlative dependence of the above listed properties. Absolutely new definition of a factor of spreading of crystalline phase in matrix is offered. <strong>Conclusion: </strong>The created formula is of consolidated nature and it can be used in technology of any ceramic material and ceramic composites. The formula will help practitioners to plan correctly and fulfill accurately all positions of technology of production of work-pieces, to carry out the most responsible thermal treatment process of technology of manufacture of work-pieces;to determine correlation between mechanical and matrix properties of materials.
基金This work is supported by the Structure Research Laboratory,University of Science and Technology of China
文摘A new type of liquid crystalline polyesters with resorcin as one part of the mesogenic unitconnected together by polymethylene, or phenylene group, and lateral groups consisting of arigid azobenzene as another part of the mesogenic unit were synthesized by interfacialpolymerization of diacyl chlorides in 1, 2-dichloroethane and 2, 4-dihydroxy-4'-nitroazobenzen inaqueous alkaline solution. The polyester structures were confirmed by proton NMR and IRspectra. Their phase transition behavior and texture were studied by polarizing microscopy andDSC.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10874021)Natural Science Foundation of Educational Department of Jiangsu Province of China (Grant No. 06kja43014)
文摘A much larger amount of bonded hydrogen was found in thick nanocrystalline diamond (NCD) films produced by only adding 0.24% N2 into 4% CH4/H2 plasma, as compared to the high quality transparent microcrystalline diamond (MCD) films, grown using the same growth parameters except for nitrogen. These experimental results clearly evidence that defect formation and impurity incorporation (for example, N and H) impeding diamond grain growth is the main formation mechanism of NCD upon nitrogen doping and strongly support the model proposed in the literature that nitrogen competes with CHx (x = 1, 2, 3) growth species for adsorption sites.
文摘MCC (micro crystalline cellulose) is a very important product in pharmaceuticals, foods, cosmetics and other industries. MCC can be made from any natural cellulose materials that have high content of cellulose ranging from pure cellulose, commercial grade cellulose to lignocellulosic materials. In this work, Beeswing (-20 L) and Chaff (5/8) which are the parts of corn cobs were used as raw materials to produce MCC via alkaline degradation, bleaching and hydrolysis. The optimum conditions of alkaline degradation, bleaching and hydrolysis were studied. MCC samples that prepared from -20 L and 5/8 were characterized through XRD (X-ray diffraction), SEM (scanning electron microscopy) and compared with the commercial MCC (Avicel PH 101). The results show that the degree of crystallinity of alkaline degradation, bleaching and hydrolysis obtained at 10% of NaOH 95 ~C for 2 h, NaCIO21.5 g 10% of acetic acid 0.5 mL 70 ~C for 2 h, 2 N of HC1, 105 ~C for 1 h showed maximum values which are 77.07%, 75.07% and 86.84%, respectively. The degree of crystallinity and the morphology of prepared MCC correspond to that of Avicel PH 101 industrial investment has been studied, the benefits of micro crystalline cellulose production (MCC) is 3,447 baht/kg. The investment of the plant is 7,263,514 baht and the breakeven point is around 6 years.
文摘Graphitic carbon nitride(g-C_(3)N_(4))has emerged as a remarkably promising photocatalyst for addressing environmental and energy issues;however,it exhibits only moderate photocatalytic activity because of its low specific surface area and high recombination of carriers.Preparation of crystalline g-C_(3)N_(4) by the molten salt method has proven to be an effective method to improve the photocatalytic activity.However,crystalline g-C_(3)N_(4) prepared by the conventional molten salt method exhibits a less regular morphology.Herein,highly crystalline g-C_(3)N_(4) hollow spheres(CCNHS)were successfully prepared by the molten salt method using cyanuric acid-melamine as a precursor.The higher crystallization of the CCNHS samples not only repaired the structural defects at the surface of the CCNHS samples but also established a built-in electric field between heptazine-based g-C_(3)N_(4) and triazine-based g-C_(3)N_(4).The hollow structure improved the level of light energy utilization and increased the number of active sites for photocatalytic reactions.Because of the above characteristics,the as-prepared CCNHS samples simultaneously realized photocatalytic hydrogen evolution with the degradation of the plasticizer bisphenol A.This research offers a new perspective on the structural optimization of supramolecular self-assembly.
文摘Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.