Rapid Fabrication of CdS Nanocrystals with Well Mesoporous Structure Under Ultrasound Irradiation at Room Temperature

Sphere-like mesoporous CdS nanocrystals with high crystallinity and big surface area were successfully fabricated by ultrasound irradiation at room temperature. The as-synthesized CdS with and without ultrasound irra diation was investigated by the characterizations of X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, and Brunauer-Emmett-Teller（BET） surface areas. The photocatalytic acti vity of the CdS was evaluated by photocatalytic degradation of methyl orange under visible light（λ〉420 nm） irradia tion. A possible mechanism for the formation of the CdS nanocrystals with mesoporous structure under ultrasound irradiation was proposed. The results show that both the template role of the triblock copolymer of P123 and the effect of ultrasound-induced aggregation are mainly responsible for the formation of mesoporous structure. On the other hand, the energy generated from acoustic cavitation can effectively accelerate the crystallization process of the amorphous CdS.

Spherical FeF3·0.33H2O/MWCNTs nanocomposite with mesoporous structure as cathode material of sodium ion battery

FeF3·0.33H2O crystallizes in hexagonal tungsten bronze structure with more opened hexagonal cavities are considered as next generation electrode materials of both lithium ion battery and sodium ion battery.In this paper the mesoporous spherical FeF3·0.33H2O/MWCNTs nanocomposite was successfully synthesized via a one-step solvothermal approach. Galvanostatic measurement showed that the performances of sodium ion batteries（SIBs） using FeF3·0.33H2O/MWCNTs as cathode material were highly dependent on the morphology and size of the as-prepared materials. Benefitting from the special mesoporous structure features, FeF3·0.33H2O/MWCNTs nanocomposite exhibits much better electrochemical performances in terms of initial discharge capacity（350.4 mAh g-1） and cycle performance（123.5 mAh g-1 after 50 cycles at 0.1 C range from 1.0 V to 4.0 V） as well as rate capacity（123.8 mAh g-1 after 25 cycles back to 0.1 C）. The excellent electrochemical performance enhancement can be attributed to the synergistic effect of the mesoporous structure and the MWCNTs conductive network, which can effectively increase the contact area between the active materials and the electrolyte, shorten the Na＋ diffusion pathway,buffer the volume change during cycling/discharge process and improve the structure stability of the FeF3·0.33H2O/MWCNTs nanocomposite.

Hard-carbon hybrid Li-ion/metal anode enabled by preferred mesoporous uniform lithium growth mechanism

To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by graphite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accumulation of dead Li,which seriously affects the cycle life of batteries and even causes safety problems.Here,by comparing graphite with two types of hard carbon,it was found that hybrid anode formed by hard carbon and lithium metal,possessing more disordered mesoporous structure and lithophilic groups,presents better performance.Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium.With the synergistic effect of this structure and lithophilic functional groups(–COOH),the reversibility of hard carbon/lithium metal hybrid anode is maintained,promoting uniform deposition of lithium metal and alleviating formation of lithium dendrites.The hybrid anode maintains a 99.5%Coulombic efficiency(CE)after 260 cycles at a specific capacity of 500 m Ah/g.This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.

Fabrication of Fe-doped Co-MOF with mesoporous structure for the optimization of supercapacitor performances

The synergy effect between different components has attracted widespread attentions because of improved activity, selectivity and stability than single component. In this paper, we fabricated mesoporous hybrid dual-metal Co and Fe containing metallic organic framework（Co/Fe-MOF）, Fe-MOF,and Co-MOF in the ionic liquid（IL）/supercritical CO2（SC）/surfactant emulsion system, and then studied the electrochemical properties of the three MOFs systematically. Experiment results indicate that, by taking advantages of coexistence of double metal, hybrid bi-metal Co/Fe-MOF exhibits the highest specific capacitance and the best cycling stability, with specific capacitance to 319.5 F/g at 1 A/g, 1.4 and 4 times for single Co-MOF and Fe-MOF, respectively.

A Novel Synthesis of Titania-silica Mixed Oxide with MesoporousStructure

Mixture formed from sonicating TiCl4 and Si(OEt)4 in the absence of water is used as precursor and hydrolyzed by using a long-chain organic ammonium bromide as a structure-directing agent. The product, titania-silica, is of mesoporous structure and characterized with SEM, FT-IR, BET, XRD and so on.

Electrochemically-induced highly reactive PdO^(*) interface on modulated mesoporous MOF-derived Co_(3)O_(4) support for selective ethanol electro-oxidation

Herein,Pd nanoparticles loaded Co_(3)O_(4)catalysts(Pd@Co_(3)O_(4))are constructed from zeolitic imidazolate framework-67(ZIF-67)for the ethanol oxidation reaction(EOR).It is demonstrated for the first time that the electrochemical conversion of Co_(3)O_(4)support would result in the charge distribution alignment at the Pd/Co_(3)O_(4)interface and induce the formation of highly reactive Pd-O species(PdO^(*)),which can further catalyze the consequent reactions of the intermediates of the ethanol oxidation.The catalyst,Pd@Co_(3)O_(4)-450,obtained under the optimized conditions exhibits excellent EOR performance with a high mass activity of 590 mA mg-1,prominent operational stability,and extraordinary capability for the electro-oxidation of acetaldehyde intermediates.Importantly,the detailed mechanism investigation reveals that Pd@Co_(3)O_(4)-450 could be benefit to the C-C bond cleavage to promote the desirable C1 pathway for the ethanol oxidation reaction.The present strategy based on the metal-support interaction of the catalyst might provide valuable inspiration for the design of high-performing catalysts for the ethanol oxidation reaction.

Atomically dispersed Fe sites on hierarchically porous carbon nanoplates for oxygen reduction reaction

Developing cost-effective,robust and stable non-precious metal catalysts for oxygen reduction reaction(ORR) is of paramount importance for electrochemical energy conversion devices such as fuel cells and metal-air batteries.Although Fe-N-C single atom catalysts(SACs) have been hailed as the most promising candidate due to the optimal binding strength of ORR intermediates on the Fe-N_(4) sites,they suffer from serious mass transport limitations as microporous templates/substrates,i.e.,zeolitic imidazolate frameworks(ZIFs),are usually employed to host the active sites.Motivated by this challenge,we herein develop a hydrogen-bonded organic framework(HOF)-assisted pyrolysis strategy to construct hierarchical micro/mesoporous carbon nanoplates for the deposition of atomically dispersed Fe-N_(4) sites.Such a design is accomplished by employing HOF nanoplates assembled from 2-aminoterephthalic acid(NH_(2)-BDC) and p-phenylenediamine(PDA) as both soft templates and C,N precursors.Benefitting from the structural merits inherited from HOF templates,the optimized catalyst(denoted as Fe-N-C SAC-950) displays outstanding ORR activity with a high half-wave potential of 0.895 V(vs.reversible hydrogen electrode(RHE)) and a small overpotential of 356 mV at 10 mA cm^(-2) for the oxygen evolution reaction(OER).More excitingly,its application potential is further verified by delivering superb rechargeability and cycling stability with a nearly unfading charge-discharge gap of 0.72 V after 160 h.Molecular dynamics(MD) simulations reveal that micro/mesoporous structure is conducive to the rapid mass transfer of O_(2),thus enhancing the ORR performance.In situ Raman results further indicate that the conversion of O_(2) to~*O_(2)-the rate-determining step(RDS) for Fe-N-C SAC-950.This work will provide a versatile strategy to construct single atom catalysts with desirable catalytic properties.

Synthesis of a new ordered mesoporous NiMoO_4 complex oxide and its efficient catalytic performance for oxidative dehydrogenation of propane

Highly ordered mesoporous NiMoO4 material was successfully synthesized using mesoporous silica KIT-6 as hard template via vacuum nanocasting method. The structure was characterized by means of XRD, TEM, N2 adsorption-desorption, Raman and FT-IR. The mesoporous NiMoO4 with the coexistence of a-NiMoO4 and fl-NiMoO4 showed well-ordered mesoporous structure, a bimodal pore size distribution and crystalline framework. The catalytic performance of NiMoOa was investigated for oxidative dehydrogenation of propane. It is demonstrated that the mesoporous NiMoO4 catalyst with more surface active oxygen species showed better catalytic performance in oxidative dehydrogena- tion of propane in comparison with bulk NiMoO4.

Aerobic oxidative desulfurization via magnetic mesoporous silica-supported tungsten oxide catalysts

It is usually difficult to remove dibenzothiophenes from diesel fuels by oxidation with molecular oxygen as an oxidant.In the study,tungsten oxide was supported on magnetic mesoporous silica by calcination to form a magnetically separable catalyst for oxidative desulfurization of diesel fuel.By tuning different calcining temperatures,the catalyst calcined at 500℃showed a high catalytic activity with molecular oxygen as the oxidant.Under optimal reaction conditions,the sulfur removal of DBT reached 99.9%at 120℃after 8 h.Furthermore,the removals of 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene could also get up to 98.2%and 92.3%under the same conditions.The reaction mechanism was explored by selective quenching experiments and FT-IR spectra.

Structures and Properties of La_(0.8)Sr_(0.2)MnO_(3+σ)^(-z) SBA-15(z=0, 1, 2, 4) Perovskite Catalysts

Mesoporous La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite oxides were synthesized via hard-templating with ordered mesoporous silica SBA-15 as the template. The as-prepared samples were characterized by XRD, SEM, AFM, BET, and XPS and the catalytic activity was tested for CO oxidation. The wide-angle XRD patterns showed that La0.8Sr0.2MnO3＋σ perovskite was formed. The SEM and AFM analyses exhibited that La0.8Sr0.2MnO3＋σ by hard-templating method had much smaller particle size（18 nm） than that（40 nm） by the sol-gel method. The perovskite-type oxides La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） also displayed a higher BET surface area from 70 to 143.7 m^2/g and a disordered mesostructure from nitrogen sorption analysis, as well as a small-angle XRD pattern. Moreover, the La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite exhibited a much higher activity in CO oxidation than the conventional La0.8Sr0.2MnO3＋σ perovskite. Further analysis by the means of XPS techniques indicated that the existence of high content of Oads/Olatt species contributed to the high activity.

Synergy of mesoporous SnO_(2)and RbF modification for high-efficiency and stable perovskite solar cells

Electron transport layer(ETL)is very critical to the performance of perovskite solar cells(PSCs),and optimization work on ETL has received extensive attentions especially on tin oxide(SnO_(2))since it is an excellent ETL material widely applied in high-efficiency PSCs.Thereinto,introducing mesoporous structure and surface modification are two important approaches which are commonly applied.Herein,based on the previous work in low-temperature fabrication process of mesoporous SnO_(2)(mSnO_(2)),we introduced a modification process with rubidium fuoride(Rb F)to the m-SnO_(2)ETL,and successfully achieved a synergy of the m-SnO_(2)and Rb F modification:not only the shortcoming of the m-SnO_(2)in interfacial traps was overcome,but also the carrier collection efficiency was further improved.The PSCs based on the m-SnO_(2)ETL with Rb F modification demonstrated outstanding performances:a champion power conversion efficiency(PCE)of 22.72%and a stability performance of maintaining 90%of the initial PCE after 300 h of MPP tracking were obtained without surface passivation of perovskite film.Hence,utilizing the abovementioned synergy is a cost-effective and feasible strategy for fabricating high-efficiency and stable PSCs since the fabrication process of the m-SnO_(2)ETL is a kind of low temperature process and RbF is cheap.

Influence of Drying Methods on Fractal Geometric Characteristics of Mesoporous Silica Aerogels

Chemical modification/ambient drying method and freeze drying method were introduced to research the synthesis of mesoporous silica aerogels. By analyzing N2 gas adsorption/desorption isotherms, the fractal geometric characteristics of gels were focused. The overall surface fractal dimensions were determined by analyzing N2 gas adsorption branch and a Frenkel-Halsey-Hill （FHH） equation was empolyed to determine surface fractal dimension Df It is found that, during ambient drying process, VTMCS/VWetgel ratio plays a crucial role in the changes of geometric feature, the key point is 50%, when the ratio is lower, and surface roughness increases with the ratio, when it exceeds 50%, the surface is almost unaffected by the modification. While freeze drying always tends to get larger Df freeze drying process could cause a rough surface of the gels. Compared with traditional porosity and specific surface area analyses, fractal geometry may be expected to be favorable for mesoporous structural analyses of materials.

Pt–Pd bimetallic nanoparticles anchored on uniform mesoporous MnO_(2) sphere as an advanced nanocatalyst for highly efficient toluene oxidation

Improving catalytic performance is a yet still challenge in thermal catalytic oxidation.Herein,uniform mesoporous MnO_(2) nanospheresupported bimetallic Pt–Pd nanoparticles were successfully fabricated via a SiO_(2) template strategy for the total catalytic degradation of volatile organic compounds at low temperature.The introduction of mesopores into the MnO_(2) support induces a large specific surface area and pore size,thus providing numerous accessible active sites and enhanced diffusion properties.Moreover,the addition of a secondary noble metal can adjust the O_(ads)/O_(latt) molar ratios,resulting in high catalytic activity.Among them,the catalyst having a Pt/Pd molar ratio of 7:3 exhibits optimized catalytic activity at a weight hourly space velocity of 36,000 mL g^(-1) h^(-1),reaching 100%toluene oxidation at 175℃ with a lower activation energy(57.0 kJ mol^(-1))than the corresponding monometallic Pt or non-Pt-based catalysts(93.8 kJ mol^(-1) and 214.2 kJ mol^(-1)).Our findings demonstrate that the uniform mesoporous MnO_(2) nanosphere-supported bimetallic Pt–Pd nanoparticles catalyst is an effective candidate for application in elimination of toluene.

Hierarchical SAPO-11 Molecular Sieve for n-Alkane Hydroisomerization Synthesized by Directing Agent Method

Silicoaluminophosphates SAPO-11 molecular sieves with small particle size and hierarchical pores were synthesized using the directing agent method.The effect of crystallization time on the particle structure,morphology,pore structure properties,and acid properties of SAPO-11 molecular sieves were investigated.Unlike the SAPO-11 molecular sieves synthesized with the conventional method,the results of XRD,SEM,BET and NH3-TPD analyses showed that the SAPO-11 molecular sieves synthesized by the directing agent method in a shorter crystallization time exhibited fine and uniform morphology.By increasing the crystallization time,the particle size of SAPO-11 molecular sieve was significantly reduced,and the mesoporous structure(intercrystalline pores)was formed.Furthermore,the external specific surface area and the total specific surface area reached 81.7 m^2/g and 192.0 m^2/g,respectively,which effectively reduced the pore mass transfer resistance and significantly increased the number of acid sites.The results of n-dodecane hydroisomerization revealed that the Pt/SAPO-11 prepared with the novel method exhibited higher catalytic activity and better hydroisomerization selectivity than that synthesized by the conventional hydrothermal method.Thus,the small particle molecular sieve showed a promising industrial application prospect to be used as catalyst support.

Plasmon Bi in-situ anchored on BiOCl nanosheets assembled microspheres towards optimized photothermal-photocatalytic performance

Interface engineering is of great importance to improve the photocatalytic performance.Herein,in-situ formation plasmon Bi/BiOCl nanosheets assembled heterojunction microspheres are fabricated via facile reductive solvothermal approach.The aldehyde group in the DMF structure is used to exert the weak reducing property of the solvent and thus strip out the metal Bi in BiOCl.The metal Bi is anchored on surface of BiOCl firmly due to in-situ formation engineered interface,which could realize efficient charge transfer channel.The resultant Bi/BiOCl heterojunctions assemblies with narrow bandgap of 3.05 eV and mesoporous structure extend the photoresponse to visible light region and could provide sufficient surface active sites.The visible-light-driven photocatalytic degradation of high-toxic norfloxacin for Bi/BiOCl heterojunctions is up to 95.5%within 20 min,representing several times that of pristine BiOCl nanosheets and the physical mixture.It is attributed to the in-situ formation of Bi/BiOCl heterojunctions and surface plasmon resonance(SPR)effect of plasmon Bi promoting charge transfer,and the obvious photothermal effect promoting the photocatalytic reaction,which are verified by experimental and density functional theory(DFT)calculations.This strategy provides ideal perspectives for fabricating metal/semiconductor heterojunctions photocatalysts with high-performance.

Carbon-coated mesoporous Co9S8 nanoparticles on reduced graphene oxide as a long-life and high-rate anode material for potassium-ion batteries

Carbon-coated mesoporous Co9S8 nanoparticles supported on reduced graphene oxide(rGO)are successfully synthesized by a simple process.This composite makes full use of the protection of the carbon layer on the surface,the good conductivity and three-dimensional(3D)structure of rGO,the mesoporous structure and nanoscale size of Co9S8,thereby presenting the excellent electrochemical performances in potassium-ion batteries,407.9 mAh·g^−1 after 100 cycles at 0.2 A·g^−1 and 215.1 mAh·g^−1 at 5 A·g^−1 in rate performances.After 1,200 cycles at 1.0 A·g^−1,this composite still remains a capacity of 210.8 mAh·g^−1.The redox reactions for potassium storage are revealed by ex-situ transmission electron microscope(TEM)/high-resolution TEM(HRTEM)images,selected area electron diffraction(SAED)patterns and X-ray photoelectron spectroscopy(XPS)spectra.The application of this composite as the host of sulfur for Li-S batteries is also explored.It sustains a capacity of 431.8 mAh·g^−1 after 800 cycles at 3 C,leading to a degradation of 0.052%per cycle.These results confirm the wide applications of this composite for electrochemical energy storage.

Atomic iron on mesoporous N-doped carbon to achieve dehydrogenation reaction at room temperature

Atomic non-noble metal materials show the potential to substitute noble metals in catalysis.Herein,melamine formaldehyde resin is developed to synthesize atomic iron on mesoporous nitrogen-doped carbon.The triazine units with abundant nitrogen content and cavity can realize effectively anchoring of single metal atoms.The atomic iron with unique charge and coordination characteristics shows superior catalytic performance in dehydrogenation reaction.Various N-heterocycles compounds and amines can be efficiently dehydrogenated into the corresponding products at room temperature,which is the mildest of all reported reaction conditions even when noble metal catalysts are considered.Therefore,development of atomic non-noble metal catalysts with mesoporous structure may provide an effective way to realize the substitution for noble metals in heterogeneous catalysis.

Graphitizing N-doped mesoporous carbon nanospheres via facile single atom iron growth for highly efficient oxygen reduction reaction

Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an urgent challenge.Herein,a simple pyrolysis of Fe3+-loaded mesoporous phenolic resin(mPF)-melamine precursor is used to prepare the single atom iron-anchored N-doped mesoporous graphitic carbon nanospheres(Fe/N-MGN).Investigation of the synthesis reveals the appropriate Fe-assisted catalysis effect and mPF template effect,which not only spurs the highly graphitic porous framework of Fe/N-MGN with plentiful pyridinic N/graphitic N,but also assures the dispersed single atom Fe anchoring without elaborated procedures.As a result,the as-synthesized Fe/N-MGN demonstrates high catalytic activity,good durability and excellent methanol tolerance for ORR.This work promises a facile method to regulate the graphitic carbon growth and single atom Fe loading for the highly efficient electrocatalysis.

Leaf-inspired design of mesoporous Sb_(2)S_(3)/N-doped Ti_(3)C_(2)T_(x) composite towards fast sodium storage

Owing to excellent conductivity and abundant surface terminals,MXene-based heterostructures have been intensively investigated as energy storage materials.However,elaborate design of the structure and composition of MXene-based hybrids towards superior electrochemical performance is still challenging.Herein,we present an ingenious leaf-inspired design for preparing a unique Sb_(2)S_(3)/nitrogen-doped Ti_(3)C_(2)T_(x)MXene(L-Sb_(2)S_(3)/Ti_(3)C_(2))hybrid.In-situ TEM observations reveal that the leaflike Sb_(2)S_(3)nanoparticles with numerous mesopores can well relieve the large volume changes via an inward pore filling mechanism with only 20%outward expansion,whereas highly conductive N-doped Ti_(3)C_(2)T_(x)nanosheets can serve as the robust mechanical support to reinforce the structural integrity of the hybrid.Benefiting from the structural and constituent merits,the L-Sb_(2)S_(3)/Ti_(3)C_(2)anode fabricated exhibits a fast sodium storage behavior in terms of outstanding rate capability(339.5 mA h g^(-1)at 2,000 mA g^(-1))and high reversible capacity at high current density(358.2 mA h g^(-1)at 1,000 mA g^(-1)after 100 cycles).Electrochemical kinetic tests and theoretical simulation further manifest that the boosted electrochemical performance mainly arises from such a unique leaf-like Sb_(2)S_(3)mesoporous nanostructure with abundant active sites,and enhanced Na^(+)adsorption energy on the heterojunction formed between Sb_(2)S_(3)nanoparticles and Ti_(3)C_2)matrix.

Rational structure design to realize high-performance SiOx@C anode material for lithium ion batteries

Silicon suboxide(SiOx)is considered to be one of the most promising materials for next-generation anode due to its high energy density.For its preparation,the wet-chemistry method is a cost-effective and readily scalable route,while the so-derived SiOx usually shows lower capacity compared with that prepared by high temperature-vacuum evaporation route.Herein,we present an elaborate particle structure design to realize the wet-chemistry preparation of a high-performance SiOx/C nanocomposite.Dandelion-like highly porous SiOx particle coated with conformal carbon layer is designed and prepared.The highly-porous SiOx skeleton provides plenty specific surface for intimate contact with carbon layer to allow a deep reduction of SiOx to a low O/Si ratio at relatively low temperature(700℃),enabling a high specific capacity.The abundant mesoscale voids effectively accommodate the volume variation of SiOx skeleton,ensuring the high structural stability of SiOx@C during lithiation/delithiation process.Meanwhile,the three-dimensional(3D)conformal carbon layer provides a fast electron/ion transportation,allowing an enhanced electrodereaction kinetics.Owing to the optimized O/Si ratio and well-engineered structure,the prepared SiOx@C electrode delivers an ultra-high capacity(1,115.8 mAh·g^-1 at 0.1 A·g^-1 after 200 cycles)and ultra-long lifespan(635 mAh·g^-1 at 2 A·g^-l after 1,000 cycles).To the best of our knowledge,the achieved combination of ultra-high specific capacity and ultra-long cycling life is unprecedented.