By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic...By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))is widely used in organic metal-ion batteries owing to its high porosity,facile synthesis,stability,and high-rate performance.However,pristine g-C_(3)N_(4)nanosheets exhibit poor ...Graphitic carbon nitride(g-C_(3)N_(4))is widely used in organic metal-ion batteries owing to its high porosity,facile synthesis,stability,and high-rate performance.However,pristine g-C_(3)N_(4)nanosheets exhibit poor electrical conductivity,irreversible metal-ion storage capacity,and short-term cycling owing to their high concentration of graphitic-N species.Herein,a series of 3,4:9,10-perylenetetracarboxylic diimide-coupled g-C_(3)N_(4)composite anode materials,CN-PI_(x)(x=0.2,0.5,0.75,and 1),was investigated,which exhibited an unusually high surface nitrogen content(23.19-39.92 at.%)and the highest pyridinic-N,pyrrolic-N,and graphitic-N contents reported to date.The CN-PI_(1)anode delivers an unprecedented and continuously increasing ultrahigh discharging capacity of exceeding 8400 mAh g^(-1)(1.96 mWh cm^(-2))at 100 mA g^(-1)with high specific energy density(E_(sp))of~7700 Wh kg^(-1)and the volumetric energy density(E_(v))of~14956 Wh L-1 and an excellent long-term stability(414 mAh g^(-1)or 0.579 mWh cm^(-2)at 1 A g^(-1)).Furthermore,the activation of the CN-PI_(x)electrodes contributes to their superior electrochemical performance,resulting from the fact that the Li+is not only stored in the CN-PI_(x)composites but also CN-PI_(x)activated the Li^(0)adlayer on the CN-PI_(1)-Cu heterojunction as an SEI layer to avoid the direct contact of Li^(0)phase and the electrolyte.The CN-PI_(1)full cell with LiCoO_(2)as the cathode delivers a discharge capacity of~587 mAh g^(-1)at a 1 A g^(-1)after 250 cycles with a Coulombic efficiency nearly 99%.This study provides a strategy to develop N-doped g-C_(3)N_(4)-based anode materials for realizing long-lasting energy storage devices.展开更多
Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction...Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction are undermined since the surface-mantled,electronegative-OH groups hinder the charge transfer between transition metal atoms and nitrogen molecules.Herein,a smart interfacing strategy is proposed to construct a coupled heterointerface between LDH and 2D g-C_(3)N_(4),which is proven by density functional theory(DFT)investigations to be favorable for nitrogen adsorption and ammonia desorption compared with neat LDH surface.The interfaced LDH and g-C_(3)N_(4) is further hybridized with a self-standing TiO_(2) nanofibrous membrane(NM)to maximize the interfacial effect owing to its high porosity and large surface area.Profited from the synergistic superiorities of the three components,the LDH@C_(3)N_(4)@TiO_(2) NM delivers superior ammonia yield(2.07×10^(−9) mol s^(−1) cm^(−2))and Faradaic efficiency(25.3%),making it a high-efficiency,noble-metal-free catalyst system toward electrocatalytic nitrogen reduction.展开更多
Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental remediation.The outstanding electronic structure and physicochemical properti...Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental remediation.The outstanding electronic structure and physicochemical properties of graphitic carbon nitride(g-C_(3)N_(4)),together with unique metal-free characteristic,make them ideal candidates for advanced photocatalysts construction.This review summarizes the up-to-date advances on g-C_(3)N_(4)based photocatalysts from ingenious-design strategies and diversified photocatalytic applications.Notably,the advantages,fabrication methods and limitations of each design strategy are systemically analyzed.In order to deeply comprehend the inner connection of theory–structure–performance upon g-C_(3)N_(4)based photocatalysts,structure/composition designs,corresponding photocatalytic activities and reaction mechanisms are jointly discussed,associated with introducing their photocatalytic applications toward water splitting,carbon dioxide/nitrogen reduction and pollutants degradation,etc.Finally,the current challenges and future perspectives for g-C_(3)N_(4)based materials for photocatalysis are briefly proposed.These design strategies and limitations are also instructive for constructing g-C_(3)N_(4) based materials in other energy and environment-related applications.展开更多
The graphitic carbon nitride(g-C_3N_4) which is a two-dimensional conjugated polymer has drawn broad interdisciplinary attention as a low-cost, metal-free, and visible-light-responsive photocatalyst in the area of env...The graphitic carbon nitride(g-C_3N_4) which is a two-dimensional conjugated polymer has drawn broad interdisciplinary attention as a low-cost, metal-free, and visible-light-responsive photocatalyst in the area of environmental remediation. The g-C_3N_4-based materials have excellent electronic band structures, electron-rich properties, basic surface functionalities, high physicochemical stabilities and are ‘‘earth-abundant.'' This review summarizes the latest progress related to the design and construction of g-C_3N_4-based materials and their applications including catalysis, sensing,imaging, and white-light-emitting diodes. An outlook on possible further developments in g-C_3N_4-based research for emerging properties and applications is also included.展开更多
The exfoliation of bulk graphitic carbon nitride(g-C_(3)N_(4))into monolayer has been intensively studied to induce maximum sur-face area for fundamental studies,but ended in failure to realize chemi-cally and physica...The exfoliation of bulk graphitic carbon nitride(g-C_(3)N_(4))into monolayer has been intensively studied to induce maximum sur-face area for fundamental studies,but ended in failure to realize chemi-cally and physically well-defined monolayer of g-C_(3)N_(4)mostly due to the difficulty in reducing the layer thickness down to an atomic level.It has,therefore,remained as a challenging issue in two-dimensional(2D)chemistry and physics communities.In this study,an“atomic monolayer of g-C_(3)N_(4)with perfect two-dimensional limit”was successfully prepared by the chemically well-defined two-step routes.The atomically resolved monolayer of g-C_(3)N_(4)was also confirmed by spectroscopic and micro-scopic analyses.In addition,the experimental Cs-HRTEM image was collected,for the first time,which was in excellent agreement with the theoretically simulated;the evidence of monolayer of g-C_(3)N_(4)in the perfect 2D limit becomes now clear from the HRTEM image of orderly hexagonal symmetry with a cavity formed by encirclement of three adjacent heptazine units.Compared to bulk g-C_(3)N_(4),the present g-C_(3)N_(4)monolayer showed significantly higher photocatalytic gen-eration of H2O2 and H2,and electrocatalytic oxygen reduction reaction.In addition,its photocatalytic efficiency for H2O2 production was found to be the best for any known g-C_(3)N_(4)nanomaterials,underscoring the remarkable advantage of monolayer formation in optimizing the catalyst performance of g-C_(3)N_(4).展开更多
Graphitic carbon nitride(g-C3N4)-based photocatalysts have shown great potential in the splitting of water.However,the intrinsic drawbacks of g-C3N4,such as low surface area,poor diffusion,and charge separation effici...Graphitic carbon nitride(g-C3N4)-based photocatalysts have shown great potential in the splitting of water.However,the intrinsic drawbacks of g-C3N4,such as low surface area,poor diffusion,and charge separation efficiency,remain as the bottleneck to achieve highly efficient hydrogen evolution.Here,a hollow oxygen-incorporated g-C3N4 nanosheet(OCN)with an improved surface area of 148.5 m2 g^−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere,wherein the C–O bonds are formed through two ways of physical adsorption and doping.The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects,leading to the formation of hollow morphology,while the O-doping results in reduced band gap of g-C3N4.The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6μmol g^−1 h^−1 for~20 h,which is over four times higher than that of g-C3N4(850.1μmol g^−1 h^−1)and outperforms most of the reported g-C3N4 catalysts.展开更多
As a prospective visible-light-responsive photochemical material,graphitic carbon nitride(g-C_(3)N_(4))has become a burgeoning research hot topics and aroused a wide interest as a metal-free semiconductor in the area ...As a prospective visible-light-responsive photochemical material,graphitic carbon nitride(g-C_(3)N_(4))has become a burgeoning research hot topics and aroused a wide interest as a metal-free semiconductor in the area of energy utilization and conversion,environmental protection due to its unique properties,such as facile synthesis,high physicochemical stability,excellent electronic band structure,and sustainability.However,the shortcomings of high recombination rate of charge carriers,relatively low electrical conductivity and visible light absorption impede its practical application.Various strategies,such as surface photosensitization,heteroatom deposition,semiconductor hybridization,etc.,have been applied to overcome the barriers.Among all the strategies,functional nanocarbon materials with various dimensions(0D~3D)attract much attention as modifiers of g-C_(3)N_(4)due to their unique electronic properties,optical properties,and easy functionalization.More importantly,the properties of these functional nanocarbon materials can be tuned by various dimensions and thus there will be a way to overcome the defects of g-C_(3)N_(4)by choosing different dimensional carbon materials.Distinguishing from some present reviews,this review starts with the fundamental physicochemical characteristics of g-C_(3)N_(4)materials,followed by analyzing the advantages of functional nanocarbon materials modifying gC_(3)N_(4).Then,we present a systematic introduction to various dimensional carbon materials.The design philosophy of carbon/g-C_(3)N_(4)composites and the advanced studies are exemplified in detail.Finally,a nichetargeting summary and outlook on the major challenges,opportunities for future research in high-powered carbon/g-C_(3)N_(4)composites was proposed.展开更多
Metals and metal oxides are widely used as photo/electro-catalysts for environmental remediation.However,there are many issues related to these metal-based catalysts for practical applications,such as high cost and de...Metals and metal oxides are widely used as photo/electro-catalysts for environmental remediation.However,there are many issues related to these metal-based catalysts for practical applications,such as high cost and detrimental environmental impact due to metal leaching.Carbon-based catalysts have the potential to overcome these limitations.In this study,monodisperse nitrogen-doped carbon nanospheres(NCs)were synthesized and loaded onto graphitic carbon nitride(g-C3N4,GCN)via a facile hydrothermal method for photocatalytic removal of sulfachloropyridazine(SCP).The prepared metal-free GCN-NC exhibited remarkably enhanced efficiency in SCP degradation.The nitrogen content in NC critically influences the physicochemical properties and performances of the resultant hybrids.The optimum nitrogen doping concentration was identified at 6.0 wt%.The SCP removal rates can be improved by a factor of 4.7 and 3.2,under UV and visible lights,by the GCN-NC composite due to the enhanced charge mobility and visible light harvesting.The mechanism of the improved photocatalytic performance and band structure alternation were further investigated by density functional theory(DFT)calculations.The DFT results confirm the high capability of the GCN-NC hybrids to activate the electron–hole pairs by reducing the band gap energy and efficiently separating electron/hole pairs.Superoxide and hydroxyl radicals are subsequently produced,leading to the efficient SCP removal.展开更多
Photoelectrochemical(PEC)water splitting is recognized as a sustainable strategy for hydrogen generation due to its abundant hydrogen source,utilization of inexhaustible solar energy,high-purity product,and environmen...Photoelectrochemical(PEC)water splitting is recognized as a sustainable strategy for hydrogen generation due to its abundant hydrogen source,utilization of inexhaustible solar energy,high-purity product,and environment-friendly process.To actualize a practical PEC water splitting,it is paramount to develop efficient,stable,safe,and low-cost photoelectrode materials.Recently,graphitic carbon nitride(g-C3N4)has aroused a great interest in the new generation photoelectrode materials because of its unique features,such as suitable band structure for water splitting,a certain range of visible light absorption,nontoxicity,and good stability.Some inherent defects of g-C3N4,however,seriously impair further improvement on PEC performance,including low electronic conductivity,high recombination rate of photogenerated charges,and limited visible light absorption at long wavelength range.Construction of g-C3N4-based nanosized heteroarrays as photoelectrodes has been regarded as a promising strategy to circumvent these inherent limitations and achieve the high-performance PEC water splitting due to the accelerated exciton separation and the reduced combination of photogenerated electrons/holes.Herein,we summarize in detail the latest progress of g-C3N4-based nanosized heteroarrays in PEC water-splitting photoelectrodes.Firstly,the unique advantages of this type of photoelectrodes,including the highly ordered nanoarray architectures and the heterojunctions,are highlighted.Then,different g-C3N4-based nanosized heteroarrays are comprehensively discussed,in terms of their fabrication methods,PEC capacities,and mechanisms,etc.To conclude,the key challenges and possible solutions for future development on g-C3N4-based nanosized heteroarray photoelectrodes are discussed.展开更多
Benzaldehyde is a highly desirable chemical due to its extensive application in medicine,chemical synthesis and food sector among others.However,its production generally involves hazardous solvents such as trifluoroto...Benzaldehyde is a highly desirable chemical due to its extensive application in medicine,chemical synthesis and food sector among others.However,its production generally involves hazardous solvents such as trifluorotoluene or acetonitrile,and its conversion,especially selectivity in the aqueous phase,is still not up to expectations.Hence,developing an environmentally benign,synthetic process for benzaldehyde production is of paramount importance.Herein,we report the preparation of a photocatalyst(PW_(12)-P-UCNS,where PW_(12)is H3PW_(12)O_(40)xH_(2)O and P-UCNS is phosphoric acid-modified unstack graphitic carbon nitride)by incorporating phosphotungstic acid on phosphoric acid-functionalised graphitic carbon nitride(g-C_(3)N_(4))nanosheets.The performance of PW_(12)-P-UCNS was tested using the benzyl alcohol photo-oxidation reaction to produce benzaldehyde in H_(2)O,at room temperature(20℃).The asprepared PW12-P-UCNS photocatalyst showed excellent photocatalytic performance with 58.3%conversion and 99.5%selectivity within 2 h.Moreover,the catalyst could be reused for at least five times without significant activity loss.Most importantly,a proposed Z-scheme mechanism of the PW_(12)-P-UCNScatalysed model reaction was revealed.We carefully investigated its transient photocurrent and electrochemical impedance,and identified superoxide radicals and photogenerated holes as the main active species through electron spin-resonance spectroscopy and scavenger experiments.Results show that the designed PW_(12)-P-UCNS photocatalyst is a highly promising candidate for benzaldehyde production through the photo-oxidation reaction in aqueous phase,under mild conditions.展开更多
In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of...In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of the tetracycline(TC)antibiotic under visible light irradiation.The experimental results exhibit that the optimal feeding weight ratio of biochar/urea is 0.03:1 in BC/g-C_(3)N_(4)composite could show the best photocatalytic activity with the degradation rate of tetracycline is 83%in 100 min irradiation.The improvement of photocatalytic activity is mainly attributed to the following two points:(i)the strong bonding with π-π stacking between BC and g-C_(3)N_(4)make the photogenerated electrons of light-excited g-C_(3)N_(4)transfer to BC,quickly and improve the separation efficiency of carriers;(ii)the introduction of BC reduces the distance for photogenerated electrons to migrate to the surface and increases the specific surface area for providing more active sites.This study provides a sustainable,economical and promising method for the synthesis of photocatalytic materials their application to wastewater treatment.展开更多
For efficient solar energy conversion,the morphology engineering of hollow graphitic carbon nitride(gC3 N4)is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transpo...For efficient solar energy conversion,the morphology engineering of hollow graphitic carbon nitride(gC3 N4)is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transport distances,but is difficult to control on account of easy structural collapse.Herein,a facile supramolecular electrostatic self-assembly strategy has been developed for the first time to fabricate mesoporous thin-walled g-C3N4 microtubes(mtw-CNT)with shell thickness of ca.13 nm.The morphological control of g-C3N4 enhances specific surface area by 12 times,induces stronger optical absorption,widens bandgap by 0.18 e V,improves photocurrent density by 2.5 times,and prolongs lifetimes of charge carriers from bulk to surface,compared with those of bulk g-C3N4.As a consequence,the transformed g-C3N4 exhibits the optimum photocatalytic H2-production rate of 3.99 mmol·h^-1·g^-1(λ>420 nm)with remarkable apparent quantum efficiency of 8.7%(λ=420±15 nm)and long-term stability.Moreover,mtw-CNT also achieves high photocatalytic CO2-to-CO selectivity of 96%(λ>420 nm),much better than those on the most previously reported porous g-C3N4 photocatalysts prepared by the conventional hard-templating and soft-templating methods.展开更多
The plasmonic photocatalyst of Pd supported on graphitic carbon nitride(Pd/g-C3N4)exhibits excellent catalytic activity in photo-induced hydrogenation of biomass-based aldehydes with environmental benign reagents of f...The plasmonic photocatalyst of Pd supported on graphitic carbon nitride(Pd/g-C3N4)exhibits excellent catalytic activity in photo-induced hydrogenation of biomass-based aldehydes with environmental benign reagents of formic acid(HCOOH)as proton source and triethylamine(TEA)as sacrificial electron donator.The chemical and configurational properties of the Pd/g-C3N4 were systematically analyzed with XRD,TEM and XPS.Under optimized conditions,27%yield of furfuryl alcohol with the corresponding turnover frequency(TOF)around 3.72 h^(-1) were obtained from furfural and TEA-HCOOH under visible-light irradiation by using Pd/g-C3N4.Our research additionally reveals that Pd atom is the true catalytic active site for the hydrogenation and the photo-promoted reduction mainly occurs through noble metal nanoparticles(NPs)-induced effect of surface plasmon resonance(SPR).The photo-catalytic system of Pd/g-C3N4 thus demonstrates a green and effective method for the hydrogenation of biomass-based aldehydes with sustainable solar energy as a driven force.展开更多
Simultaneously adjusting the surface,crystallographic and electronic structures of nanomaterials provide a new avenue for rational design of advanced photocatalyst yet it is challenging.In this work,a surface and stru...Simultaneously adjusting the surface,crystallographic and electronic structures of nanomaterials provide a new avenue for rational design of advanced photocatalyst yet it is challenging.In this work,a surface and structural engineering strategy is developed to simultaneously realize the 2D amorphous structure and oxygen(O)-doping in graphitic carbon nitride(g–C_(3)N_(4))via the assistance of supercritical carbon dioxide(SCCO_(2)).The 2D O-doped amorphous g-C_(3)N_(4)nanosheets display greatly enhanced photocatalytic CO_(2)reduction and methylene blue degradation performances.The synthesis method as well as the mechanism of the enhanced photocatalytic activity was investigated,wherein the introduction of 2D amorphous structure and O dopant in the g-C_(3)N_(4)contributes to the increased surface area,abundant active sites,wider visible-light absorption range and efficient charge separation property,and thus the outstanding photocatalytic activities can be obtained.Its photocatalytic CH_(4)evolution rate and MB degradation rete are 5.1 and 7.0 times enhancement over bulk crystalline g-C_(3)N_(4),respectively.This work presents a great promising way for designing and developing advanced photocatalysts.展开更多
In order to overcome the problem that the low conductivity and high content of graphitic N will lead to serious irreversible capacity loss,magnesiothermic denitriding method was employed to fabricate nitrogen deficien...In order to overcome the problem that the low conductivity and high content of graphitic N will lead to serious irreversible capacity loss,magnesiothermic denitriding method was employed to fabricate nitrogen deficient g-C3N4 (ND-g-C3N4).By controlling the reaction conditions,ND-g-C3N4-675 with optimal electrochemical properties was obtained.The ND-g-C3N4-675 has thinner two-dimensional porous structure,with high specific surface area and good conductivity.The ND-g-C3N4-675 showed superior cyclic stability and rate capability (After 500 cycles under 1 000 mA·g-1,2 264.9 mAh·g-1 was obtained).Moreover,it presented high initial coulombic efficiency (42.2%).展开更多
Electrochemical nitrogen reduction reaction(NRR) to produce ammonia under ambient conditions is considered as a promising approach to tackle the energy-intensive Haber-Bosch process,but the low Faradaic efficiency and...Electrochemical nitrogen reduction reaction(NRR) to produce ammonia under ambient conditions is considered as a promising approach to tackle the energy-intensive Haber-Bosch process,but the low Faradaic efficiency and yield of NH_3 are still a challenge.Herein,a carbon-vacancies enriched mesoporous g-C_3 N_4 is developed by an in situ Zr doping strategy.The in situ mesoporous-forming mechanism is deeply understood by TPSR to reveal the functions of Zr dopant that pulls C from the precursor of C_3 N_4,resulting the formation of homogeneous mesopores with about 57% of the one C-defective s-triazine ring in C_3 N_4.Due to the defect sites obtained in metal doping synthesis,the RuAu bimetallic supported catalyst(RuAu_3/0.3 Zr-C_3 N_4) exhibits effective NRR performance with a Faraday efficiency of 11.54% and an NH_3 yield of 5.28 μg h^(-1) mg_(cat) ^(-1).at-0.1 V(RHE),which is nearly 10 times higher than that of RuAu_3/C_3 N_4 catalyst.This work proposes a simple and template-free preparation method for the high defect density mesoporous C_3 N_4,and provides new possibilities of a wide application of mesopore g-C3 N4.展开更多
N-doped carbons as one of the most prominent anode materials to replace standard graphite exhibit outstanding Li+storage performance.However,N-doped carbon anodes still suffer from low N-doping levels and low initial ...N-doped carbons as one of the most prominent anode materials to replace standard graphite exhibit outstanding Li+storage performance.However,N-doped carbon anodes still suffer from low N-doping levels and low initial Coulombic efficiency(ICE).In this study,high N-doped and low graphitic-N carbons(LGNCs)with enhanced ICE were synthesized by taking advantage of a denitrification strategy for graphitic carbon nitride(g-C_(3)N_(4)).In brief,more than 14.5 at%of N from g-C_(3)N_(4)(55.1 at%N)was retained by reacting graphitic-N with lithium,which was subsequently removed.As graphitic-N is largely responsible for the irreversible capacity,the anode's performance was significantly increased.Compared to general N-doped carbons with high graphitic-N proportion(>50%)and low N content(<15 at%),LGNCs delivered a low proportion of 10.8%-17.2% within the high N-doping content of 14.5-42.7 at%,leading to an enhanced specific capacity of 1499.9mAh g^(-1) at an ICE of 93.7% for the optimal sample of LGNC(4:1).This study provides a facile strategy to control the N content and speciation,achieving both high Li+storage capacity and high ICE,and thus promoting research and application of N-doped carbon materials.展开更多
Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomerat...Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomeration hamper its electrochemical performance.In the present study,we have grown NiSe nanoparticles on two-dimensional(2D)graphitic carbon nitride(g-C_(3)N_(4))nanosheets to realize three-dimensional(3D)architecture.The 2D support,high nitrogen content,and features of g-C_(3)N_(4)enhanced the specific capacity of the NiSe/g-C_(3)N_(4)nanocomposite material.The resulting nanocomposite shows a specific capacity of 320 mA h g^(-1)at a current density of 1 A g^(-1),which is considerably higher than pristine NiSe.Later,the hybrid supercapacitor(HSC)device was fabricated using NiSe/g-C_(3)N_(4)composite as positive and activated carbon(AC)as negative electrodes.The cell delivered an energy density of 52.5 Wh kg^(-1)at a power density of 1488 W kg^(-1)with excellent cyclic stability of 84.9%over 8000 cycles.The electrochemical performance enhancement corresponds to a 3D structure,high electrochemical active sites,and improved charge transportation at the electrode/electrolyte interface.Thus,the present work offers an easy approach and architectural design for high-performance HSC.展开更多
Heterojunction composites were prepared by silane coupling agent grafting from synthesized graphitic carbon nitride(g-C_(3)N_(4))and commercially available zirconia(ZrO_(2)).The samples were characterized by X-ray dif...Heterojunction composites were prepared by silane coupling agent grafting from synthesized graphitic carbon nitride(g-C_(3)N_(4))and commercially available zirconia(ZrO_(2)).The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,UV-vis diffuse reflectance spectroscopy(DRS),photoluminescence(PL)spectroscopy,and electrochemical impedance spectroscopy(EIS).The photocatalytic activity of the composites was evaluated by the degradation of methylene blue(MB)under visible light irradiation.The results showed that heterojunction composites of g-C_(3)N_(4) and ZrO_(2) could be successfully prepared by coupling agent grafting.The optimal mass ratio of g-C_(3)N_(4) and ZrO_(2) was 2:1,with an activity that was 3.8 times higher than g-C_(3)N_(4) and 15.3 times higher than ZrO_(2).This was ascribed to the stronger light absorption,faster interfacial charge transfer,and lower photogenerated carrier recombination of the heterojunction composites.展开更多
基金the National Natural Science Foundation of China (22178120)Guangdong Natural Science Funds for Distinguished Young Scholar (2017A030306022)Guangzhou Technology Project (202002030164)。
文摘By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.
基金supported by the“Human Resources Program in Energy Technology”of the Korea Institute of Energy Technology Evaluation and Planning,granted financial resources from the Ministry of Trade,Industry&Energy,Republic of Korea(Grant No.20204010600100)the Basic Science Research Program through the National Research Foundation of Korea,funded by the Ministry of Education,Republic of Korea(Grant No.NRF-2019R1I1A3A01046928).
文摘Graphitic carbon nitride(g-C_(3)N_(4))is widely used in organic metal-ion batteries owing to its high porosity,facile synthesis,stability,and high-rate performance.However,pristine g-C_(3)N_(4)nanosheets exhibit poor electrical conductivity,irreversible metal-ion storage capacity,and short-term cycling owing to their high concentration of graphitic-N species.Herein,a series of 3,4:9,10-perylenetetracarboxylic diimide-coupled g-C_(3)N_(4)composite anode materials,CN-PI_(x)(x=0.2,0.5,0.75,and 1),was investigated,which exhibited an unusually high surface nitrogen content(23.19-39.92 at.%)and the highest pyridinic-N,pyrrolic-N,and graphitic-N contents reported to date.The CN-PI_(1)anode delivers an unprecedented and continuously increasing ultrahigh discharging capacity of exceeding 8400 mAh g^(-1)(1.96 mWh cm^(-2))at 100 mA g^(-1)with high specific energy density(E_(sp))of~7700 Wh kg^(-1)and the volumetric energy density(E_(v))of~14956 Wh L-1 and an excellent long-term stability(414 mAh g^(-1)or 0.579 mWh cm^(-2)at 1 A g^(-1)).Furthermore,the activation of the CN-PI_(x)electrodes contributes to their superior electrochemical performance,resulting from the fact that the Li+is not only stored in the CN-PI_(x)composites but also CN-PI_(x)activated the Li^(0)adlayer on the CN-PI_(1)-Cu heterojunction as an SEI layer to avoid the direct contact of Li^(0)phase and the electrolyte.The CN-PI_(1)full cell with LiCoO_(2)as the cathode delivers a discharge capacity of~587 mAh g^(-1)at a 1 A g^(-1)after 250 cycles with a Coulombic efficiency nearly 99%.This study provides a strategy to develop N-doped g-C_(3)N_(4)-based anode materials for realizing long-lasting energy storage devices.
基金financially supported by the National Natural Science Foundation of China(No.52173055 and 21961132024)the Natural Science Foundation of Shanghai(No.19ZR1401100)+3 种基金the International Cooperation Fund of Science and Technology Commission of Shanghai Municipality(No.21130750100)the Innovation Program of Shanghai Municipal Education Commission(No.2017-01-07-00-03-E00024)the Fundamental Research Funds for the Central Universities(No.18D310109)the DHU Distinguished Young Professor Program(No.LZA2020001).
文摘Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction are undermined since the surface-mantled,electronegative-OH groups hinder the charge transfer between transition metal atoms and nitrogen molecules.Herein,a smart interfacing strategy is proposed to construct a coupled heterointerface between LDH and 2D g-C_(3)N_(4),which is proven by density functional theory(DFT)investigations to be favorable for nitrogen adsorption and ammonia desorption compared with neat LDH surface.The interfaced LDH and g-C_(3)N_(4) is further hybridized with a self-standing TiO_(2) nanofibrous membrane(NM)to maximize the interfacial effect owing to its high porosity and large surface area.Profited from the synergistic superiorities of the three components,the LDH@C_(3)N_(4)@TiO_(2) NM delivers superior ammonia yield(2.07×10^(−9) mol s^(−1) cm^(−2))and Faradaic efficiency(25.3%),making it a high-efficiency,noble-metal-free catalyst system toward electrocatalytic nitrogen reduction.
基金supported by the National Natural Science Foundation of China(21875118,22111530112)the support from the Smart Sensing Interdisciplinary Science Center,Nankai University。
文摘Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental remediation.The outstanding electronic structure and physicochemical properties of graphitic carbon nitride(g-C_(3)N_(4)),together with unique metal-free characteristic,make them ideal candidates for advanced photocatalysts construction.This review summarizes the up-to-date advances on g-C_(3)N_(4)based photocatalysts from ingenious-design strategies and diversified photocatalytic applications.Notably,the advantages,fabrication methods and limitations of each design strategy are systemically analyzed.In order to deeply comprehend the inner connection of theory–structure–performance upon g-C_(3)N_(4)based photocatalysts,structure/composition designs,corresponding photocatalytic activities and reaction mechanisms are jointly discussed,associated with introducing their photocatalytic applications toward water splitting,carbon dioxide/nitrogen reduction and pollutants degradation,etc.Finally,the current challenges and future perspectives for g-C_(3)N_(4)based materials for photocatalysis are briefly proposed.These design strategies and limitations are also instructive for constructing g-C_(3)N_(4) based materials in other energy and environment-related applications.
文摘The graphitic carbon nitride(g-C_3N_4) which is a two-dimensional conjugated polymer has drawn broad interdisciplinary attention as a low-cost, metal-free, and visible-light-responsive photocatalyst in the area of environmental remediation. The g-C_3N_4-based materials have excellent electronic band structures, electron-rich properties, basic surface functionalities, high physicochemical stabilities and are ‘‘earth-abundant.'' This review summarizes the latest progress related to the design and construction of g-C_3N_4-based materials and their applications including catalysis, sensing,imaging, and white-light-emitting diodes. An outlook on possible further developments in g-C_3N_4-based research for emerging properties and applications is also included.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2020R1I1A1A01072161)and under the framework of the International Cooperation Program managed by NRF(No.2017K2A9A2A10013104)supported by the NRF grant funded by the Korea government(MSIP)(No.NRF-2020R1A2C3008671).
文摘The exfoliation of bulk graphitic carbon nitride(g-C_(3)N_(4))into monolayer has been intensively studied to induce maximum sur-face area for fundamental studies,but ended in failure to realize chemi-cally and physically well-defined monolayer of g-C_(3)N_(4)mostly due to the difficulty in reducing the layer thickness down to an atomic level.It has,therefore,remained as a challenging issue in two-dimensional(2D)chemistry and physics communities.In this study,an“atomic monolayer of g-C_(3)N_(4)with perfect two-dimensional limit”was successfully prepared by the chemically well-defined two-step routes.The atomically resolved monolayer of g-C_(3)N_(4)was also confirmed by spectroscopic and micro-scopic analyses.In addition,the experimental Cs-HRTEM image was collected,for the first time,which was in excellent agreement with the theoretically simulated;the evidence of monolayer of g-C_(3)N_(4)in the perfect 2D limit becomes now clear from the HRTEM image of orderly hexagonal symmetry with a cavity formed by encirclement of three adjacent heptazine units.Compared to bulk g-C_(3)N_(4),the present g-C_(3)N_(4)monolayer showed significantly higher photocatalytic gen-eration of H2O2 and H2,and electrocatalytic oxygen reduction reaction.In addition,its photocatalytic efficiency for H2O2 production was found to be the best for any known g-C_(3)N_(4)nanomaterials,underscoring the remarkable advantage of monolayer formation in optimizing the catalyst performance of g-C_(3)N_(4).
基金This work was supported by the National Science Foundation of China(51772152,51702129,51572114,51972150,21908110,and 51902161)Fundamental Research Funds for the Central Universities(30919011269,30919011110,and 1191030558)+3 种基金Y.W.thanks the Key University Science Research Project of Jiangsu province(16KJB430009)Y.Z.thanks for the support from the Postdoctoral Science Foundation(2018M630527)China Scholarship Council(201708320150)J.S.thanks the Natural Science Foundation of Jiangsu Province(BK20190479,1192261031693).
文摘Graphitic carbon nitride(g-C3N4)-based photocatalysts have shown great potential in the splitting of water.However,the intrinsic drawbacks of g-C3N4,such as low surface area,poor diffusion,and charge separation efficiency,remain as the bottleneck to achieve highly efficient hydrogen evolution.Here,a hollow oxygen-incorporated g-C3N4 nanosheet(OCN)with an improved surface area of 148.5 m2 g^−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere,wherein the C–O bonds are formed through two ways of physical adsorption and doping.The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects,leading to the formation of hollow morphology,while the O-doping results in reduced band gap of g-C3N4.The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6μmol g^−1 h^−1 for~20 h,which is over four times higher than that of g-C3N4(850.1μmol g^−1 h^−1)and outperforms most of the reported g-C3N4 catalysts.
基金supported by the Startup Foundation of China(3160011181808)。
文摘As a prospective visible-light-responsive photochemical material,graphitic carbon nitride(g-C_(3)N_(4))has become a burgeoning research hot topics and aroused a wide interest as a metal-free semiconductor in the area of energy utilization and conversion,environmental protection due to its unique properties,such as facile synthesis,high physicochemical stability,excellent electronic band structure,and sustainability.However,the shortcomings of high recombination rate of charge carriers,relatively low electrical conductivity and visible light absorption impede its practical application.Various strategies,such as surface photosensitization,heteroatom deposition,semiconductor hybridization,etc.,have been applied to overcome the barriers.Among all the strategies,functional nanocarbon materials with various dimensions(0D~3D)attract much attention as modifiers of g-C_(3)N_(4)due to their unique electronic properties,optical properties,and easy functionalization.More importantly,the properties of these functional nanocarbon materials can be tuned by various dimensions and thus there will be a way to overcome the defects of g-C_(3)N_(4)by choosing different dimensional carbon materials.Distinguishing from some present reviews,this review starts with the fundamental physicochemical characteristics of g-C_(3)N_(4)materials,followed by analyzing the advantages of functional nanocarbon materials modifying gC_(3)N_(4).Then,we present a systematic introduction to various dimensional carbon materials.The design philosophy of carbon/g-C_(3)N_(4)composites and the advanced studies are exemplified in detail.Finally,a nichetargeting summary and outlook on the major challenges,opportunities for future research in high-powered carbon/g-C_(3)N_(4)composites was proposed.
基金the partial support from the Australian Research Council Discovery Project(No:DP170104264)
文摘Metals and metal oxides are widely used as photo/electro-catalysts for environmental remediation.However,there are many issues related to these metal-based catalysts for practical applications,such as high cost and detrimental environmental impact due to metal leaching.Carbon-based catalysts have the potential to overcome these limitations.In this study,monodisperse nitrogen-doped carbon nanospheres(NCs)were synthesized and loaded onto graphitic carbon nitride(g-C3N4,GCN)via a facile hydrothermal method for photocatalytic removal of sulfachloropyridazine(SCP).The prepared metal-free GCN-NC exhibited remarkably enhanced efficiency in SCP degradation.The nitrogen content in NC critically influences the physicochemical properties and performances of the resultant hybrids.The optimum nitrogen doping concentration was identified at 6.0 wt%.The SCP removal rates can be improved by a factor of 4.7 and 3.2,under UV and visible lights,by the GCN-NC composite due to the enhanced charge mobility and visible light harvesting.The mechanism of the improved photocatalytic performance and band structure alternation were further investigated by density functional theory(DFT)calculations.The DFT results confirm the high capability of the GCN-NC hybrids to activate the electron–hole pairs by reducing the band gap energy and efficiently separating electron/hole pairs.Superoxide and hydroxyl radicals are subsequently produced,leading to the efficient SCP removal.
基金This study was supported by Developed and Applied Funding of Tianjin Normal University(135202XK1702)Program for Innovative Research in the University of Tianjin(TD13-5077)+1 种基金National Natural Science Foundation of China(Number 21905202)Australian Research Council(ARC)through Discovery Early Career Researcher Awards(DECRA,DE170100871).
文摘Photoelectrochemical(PEC)water splitting is recognized as a sustainable strategy for hydrogen generation due to its abundant hydrogen source,utilization of inexhaustible solar energy,high-purity product,and environment-friendly process.To actualize a practical PEC water splitting,it is paramount to develop efficient,stable,safe,and low-cost photoelectrode materials.Recently,graphitic carbon nitride(g-C3N4)has aroused a great interest in the new generation photoelectrode materials because of its unique features,such as suitable band structure for water splitting,a certain range of visible light absorption,nontoxicity,and good stability.Some inherent defects of g-C3N4,however,seriously impair further improvement on PEC performance,including low electronic conductivity,high recombination rate of photogenerated charges,and limited visible light absorption at long wavelength range.Construction of g-C3N4-based nanosized heteroarrays as photoelectrodes has been regarded as a promising strategy to circumvent these inherent limitations and achieve the high-performance PEC water splitting due to the accelerated exciton separation and the reduced combination of photogenerated electrons/holes.Herein,we summarize in detail the latest progress of g-C3N4-based nanosized heteroarrays in PEC water-splitting photoelectrodes.Firstly,the unique advantages of this type of photoelectrodes,including the highly ordered nanoarray architectures and the heterojunctions,are highlighted.Then,different g-C3N4-based nanosized heteroarrays are comprehensively discussed,in terms of their fabrication methods,PEC capacities,and mechanisms,etc.To conclude,the key challenges and possible solutions for future development on g-C3N4-based nanosized heteroarray photoelectrodes are discussed.
基金This research was supported by the National Nature Science Foundation of China(21625101,21521005,and 21808011)the National Key Research and Development Program of China(2017YFB0307303)+1 种基金Beijing Natural Science Foundation(2202039)the Fundamental Research Funds for the Central Universities(XK1802-6,XK1902,and 12060093063).
文摘Benzaldehyde is a highly desirable chemical due to its extensive application in medicine,chemical synthesis and food sector among others.However,its production generally involves hazardous solvents such as trifluorotoluene or acetonitrile,and its conversion,especially selectivity in the aqueous phase,is still not up to expectations.Hence,developing an environmentally benign,synthetic process for benzaldehyde production is of paramount importance.Herein,we report the preparation of a photocatalyst(PW_(12)-P-UCNS,where PW_(12)is H3PW_(12)O_(40)xH_(2)O and P-UCNS is phosphoric acid-modified unstack graphitic carbon nitride)by incorporating phosphotungstic acid on phosphoric acid-functionalised graphitic carbon nitride(g-C_(3)N_(4))nanosheets.The performance of PW_(12)-P-UCNS was tested using the benzyl alcohol photo-oxidation reaction to produce benzaldehyde in H_(2)O,at room temperature(20℃).The asprepared PW12-P-UCNS photocatalyst showed excellent photocatalytic performance with 58.3%conversion and 99.5%selectivity within 2 h.Moreover,the catalyst could be reused for at least five times without significant activity loss.Most importantly,a proposed Z-scheme mechanism of the PW_(12)-P-UCNScatalysed model reaction was revealed.We carefully investigated its transient photocurrent and electrochemical impedance,and identified superoxide radicals and photogenerated holes as the main active species through electron spin-resonance spectroscopy and scavenger experiments.Results show that the designed PW_(12)-P-UCNS photocatalyst is a highly promising candidate for benzaldehyde production through the photo-oxidation reaction in aqueous phase,under mild conditions.
基金the founding support from the National Natural Science Foundation of China (21906072, 22006057 and 31971616)the Natural Science Foundation of Jiangsu Province (BK20190982)+4 种基金“Doctor of Mass Entrepreneurship and Innovation” Project in Jiangsu ProvinceHenan Postdoctoral Foundation (202003013)the Science and Technology Research Project of the Department of Education of Jilin Province (JJKH20200039KJ)the Science and Technology Research Project of Jilin City (20190104120, 201830811)the Project of Jilin Provincial Science and Technology Development Plan (20190201277JC, 20200301046RQ, YDZJ202101ZYTS070)
文摘In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of the tetracycline(TC)antibiotic under visible light irradiation.The experimental results exhibit that the optimal feeding weight ratio of biochar/urea is 0.03:1 in BC/g-C_(3)N_(4)composite could show the best photocatalytic activity with the degradation rate of tetracycline is 83%in 100 min irradiation.The improvement of photocatalytic activity is mainly attributed to the following two points:(i)the strong bonding with π-π stacking between BC and g-C_(3)N_(4)make the photogenerated electrons of light-excited g-C_(3)N_(4)transfer to BC,quickly and improve the separation efficiency of carriers;(ii)the introduction of BC reduces the distance for photogenerated electrons to migrate to the surface and increases the specific surface area for providing more active sites.This study provides a sustainable,economical and promising method for the synthesis of photocatalytic materials their application to wastewater treatment.
基金financially supported by the National Natural Science Foundation of China(21902051)the Natural Science Foundation of Fujian Province(2017J01014 and 2019J05090)the Graphene Power and Composite Research Center of Fujian Province(2017H2001)。
文摘For efficient solar energy conversion,the morphology engineering of hollow graphitic carbon nitride(gC3 N4)is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transport distances,but is difficult to control on account of easy structural collapse.Herein,a facile supramolecular electrostatic self-assembly strategy has been developed for the first time to fabricate mesoporous thin-walled g-C3N4 microtubes(mtw-CNT)with shell thickness of ca.13 nm.The morphological control of g-C3N4 enhances specific surface area by 12 times,induces stronger optical absorption,widens bandgap by 0.18 e V,improves photocurrent density by 2.5 times,and prolongs lifetimes of charge carriers from bulk to surface,compared with those of bulk g-C3N4.As a consequence,the transformed g-C3N4 exhibits the optimum photocatalytic H2-production rate of 3.99 mmol·h^-1·g^-1(λ>420 nm)with remarkable apparent quantum efficiency of 8.7%(λ=420±15 nm)and long-term stability.Moreover,mtw-CNT also achieves high photocatalytic CO2-to-CO selectivity of 96%(λ>420 nm),much better than those on the most previously reported porous g-C3N4 photocatalysts prepared by the conventional hard-templating and soft-templating methods.
基金We are grateful for the financial support from National Natural Science Foundation of China(U1810111,21676089)Natural Science Foundation of Guangdong Province,China(2018B030311010)+1 种基金Youth Science and Technology Innovation Talent of Guangdong TeZhi Plan(2019TQ05L111)Key Laboratory of Biomass Chemical Engineering of Ministry of Education,Zhejiang University(2018BCE002).
文摘The plasmonic photocatalyst of Pd supported on graphitic carbon nitride(Pd/g-C3N4)exhibits excellent catalytic activity in photo-induced hydrogenation of biomass-based aldehydes with environmental benign reagents of formic acid(HCOOH)as proton source and triethylamine(TEA)as sacrificial electron donator.The chemical and configurational properties of the Pd/g-C3N4 were systematically analyzed with XRD,TEM and XPS.Under optimized conditions,27%yield of furfuryl alcohol with the corresponding turnover frequency(TOF)around 3.72 h^(-1) were obtained from furfural and TEA-HCOOH under visible-light irradiation by using Pd/g-C3N4.Our research additionally reveals that Pd atom is the true catalytic active site for the hydrogenation and the photo-promoted reduction mainly occurs through noble metal nanoparticles(NPs)-induced effect of surface plasmon resonance(SPR).The photo-catalytic system of Pd/g-C3N4 thus demonstrates a green and effective method for the hydrogenation of biomass-based aldehydes with sustainable solar energy as a driven force.
基金financially supported by the National Natural Science Foundation of China(No.21773216,51173170,21703207)the financial support from the Innovation Talents Award of Henan Province(114200510019)+1 种基金Science and Technology Program from Henan province(152102410010)the China Postdoctoral Science Foundation(No.2018T110738)。
文摘Simultaneously adjusting the surface,crystallographic and electronic structures of nanomaterials provide a new avenue for rational design of advanced photocatalyst yet it is challenging.In this work,a surface and structural engineering strategy is developed to simultaneously realize the 2D amorphous structure and oxygen(O)-doping in graphitic carbon nitride(g–C_(3)N_(4))via the assistance of supercritical carbon dioxide(SCCO_(2)).The 2D O-doped amorphous g-C_(3)N_(4)nanosheets display greatly enhanced photocatalytic CO_(2)reduction and methylene blue degradation performances.The synthesis method as well as the mechanism of the enhanced photocatalytic activity was investigated,wherein the introduction of 2D amorphous structure and O dopant in the g-C_(3)N_(4)contributes to the increased surface area,abundant active sites,wider visible-light absorption range and efficient charge separation property,and thus the outstanding photocatalytic activities can be obtained.Its photocatalytic CH_(4)evolution rate and MB degradation rete are 5.1 and 7.0 times enhancement over bulk crystalline g-C_(3)N_(4),respectively.This work presents a great promising way for designing and developing advanced photocatalysts.
基金the National Natural Science Foundation of China(No.21473128)。
文摘In order to overcome the problem that the low conductivity and high content of graphitic N will lead to serious irreversible capacity loss,magnesiothermic denitriding method was employed to fabricate nitrogen deficient g-C3N4 (ND-g-C3N4).By controlling the reaction conditions,ND-g-C3N4-675 with optimal electrochemical properties was obtained.The ND-g-C3N4-675 has thinner two-dimensional porous structure,with high specific surface area and good conductivity.The ND-g-C3N4-675 showed superior cyclic stability and rate capability (After 500 cycles under 1 000 mA·g-1,2 264.9 mAh·g-1 was obtained).Moreover,it presented high initial coulombic efficiency (42.2%).
基金supported by the National Natural Science Foundation of China (No. 21978259)the Zhejiang Provincial Natural Science Foundation of China (No. LR17B060002)the Fundamental Research Funds for the Central Universities。
文摘Electrochemical nitrogen reduction reaction(NRR) to produce ammonia under ambient conditions is considered as a promising approach to tackle the energy-intensive Haber-Bosch process,but the low Faradaic efficiency and yield of NH_3 are still a challenge.Herein,a carbon-vacancies enriched mesoporous g-C_3 N_4 is developed by an in situ Zr doping strategy.The in situ mesoporous-forming mechanism is deeply understood by TPSR to reveal the functions of Zr dopant that pulls C from the precursor of C_3 N_4,resulting the formation of homogeneous mesopores with about 57% of the one C-defective s-triazine ring in C_3 N_4.Due to the defect sites obtained in metal doping synthesis,the RuAu bimetallic supported catalyst(RuAu_3/0.3 Zr-C_3 N_4) exhibits effective NRR performance with a Faraday efficiency of 11.54% and an NH_3 yield of 5.28 μg h^(-1) mg_(cat) ^(-1).at-0.1 V(RHE),which is nearly 10 times higher than that of RuAu_3/C_3 N_4 catalyst.This work proposes a simple and template-free preparation method for the high defect density mesoporous C_3 N_4,and provides new possibilities of a wide application of mesopore g-C3 N4.
基金National Natural Science Foundation of China,Grant/Award Number:51777138Deutsche Forschungsgemeinschaft(DFG,German Research Foundation),Grant/Award Number:491183248Open Access Publishing Fund of the University of Bayreuth。
文摘N-doped carbons as one of the most prominent anode materials to replace standard graphite exhibit outstanding Li+storage performance.However,N-doped carbon anodes still suffer from low N-doping levels and low initial Coulombic efficiency(ICE).In this study,high N-doped and low graphitic-N carbons(LGNCs)with enhanced ICE were synthesized by taking advantage of a denitrification strategy for graphitic carbon nitride(g-C_(3)N_(4)).In brief,more than 14.5 at%of N from g-C_(3)N_(4)(55.1 at%N)was retained by reacting graphitic-N with lithium,which was subsequently removed.As graphitic-N is largely responsible for the irreversible capacity,the anode's performance was significantly increased.Compared to general N-doped carbons with high graphitic-N proportion(>50%)and low N content(<15 at%),LGNCs delivered a low proportion of 10.8%-17.2% within the high N-doping content of 14.5-42.7 at%,leading to an enhanced specific capacity of 1499.9mAh g^(-1) at an ICE of 93.7% for the optimal sample of LGNC(4:1).This study provides a facile strategy to control the N content and speciation,achieving both high Li+storage capacity and high ICE,and thus promoting research and application of N-doped carbon materials.
基金the financial support from UGC NET-JRF(517906)support from UGC NFOBC(202021-201610071195)+1 种基金funding from SERB(EEQ/2022/001076)DST-SERB for startup research grant(SRG/2021/001791)。
文摘Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomeration hamper its electrochemical performance.In the present study,we have grown NiSe nanoparticles on two-dimensional(2D)graphitic carbon nitride(g-C_(3)N_(4))nanosheets to realize three-dimensional(3D)architecture.The 2D support,high nitrogen content,and features of g-C_(3)N_(4)enhanced the specific capacity of the NiSe/g-C_(3)N_(4)nanocomposite material.The resulting nanocomposite shows a specific capacity of 320 mA h g^(-1)at a current density of 1 A g^(-1),which is considerably higher than pristine NiSe.Later,the hybrid supercapacitor(HSC)device was fabricated using NiSe/g-C_(3)N_(4)composite as positive and activated carbon(AC)as negative electrodes.The cell delivered an energy density of 52.5 Wh kg^(-1)at a power density of 1488 W kg^(-1)with excellent cyclic stability of 84.9%over 8000 cycles.The electrochemical performance enhancement corresponds to a 3D structure,high electrochemical active sites,and improved charge transportation at the electrode/electrolyte interface.Thus,the present work offers an easy approach and architectural design for high-performance HSC.
基金Natural Science Foundation of Heilongjiang Province of China(LH2022E030)National Natural Science Foundation of China(21905042).
文摘Heterojunction composites were prepared by silane coupling agent grafting from synthesized graphitic carbon nitride(g-C_(3)N_(4))and commercially available zirconia(ZrO_(2)).The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,UV-vis diffuse reflectance spectroscopy(DRS),photoluminescence(PL)spectroscopy,and electrochemical impedance spectroscopy(EIS).The photocatalytic activity of the composites was evaluated by the degradation of methylene blue(MB)under visible light irradiation.The results showed that heterojunction composites of g-C_(3)N_(4) and ZrO_(2) could be successfully prepared by coupling agent grafting.The optimal mass ratio of g-C_(3)N_(4) and ZrO_(2) was 2:1,with an activity that was 3.8 times higher than g-C_(3)N_(4) and 15.3 times higher than ZrO_(2).This was ascribed to the stronger light absorption,faster interfacial charge transfer,and lower photogenerated carrier recombination of the heterojunction composites.