In situ synthesis of a nickel boron oxide/graphdiyne hybrid for enhanced photo/electrocatalytic H_(2) evolution

Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid catalyst was prepared by a facile synthetic approach.Benefitting from the strong electron donating ability of graphdiyne,NiBi/GDY showed an optimized electronic structure containing lower valence nickel atoms and demonstrated improved catalytic performance.As expected,NiBi/GDY displayed a high photocatalytic H2 evolution rate of 4.54 mmol g^(-1)h^(-1),2.9 and 4.5 times higher than those of NiBi/graphene and NiBi,respectively.NiBi/GDY also displayed outstanding electrocatalytic H2 evolution activity in 1.0 M KOH solution,with a current density of 400 mA/cm^(2)at an overpotential of 478.0 mV,which is lower than that of commercial Pt/C(505.3 mV@400 mA/cm^(2)).This work demonstrates that GDY is an ideal support for the development of highly active catalysts for photo/electrocatalytic H2 evolution.

Self-template-oriented synthesis of lead-free perovskite Cs_(3)Bi_(2)I_(9) nanosheets for boosting photocatalysis of CO_(2) reduction over Z-scheme heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)

Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial photosynthesis in recent years.However,the toxicity of lead in LHP seriously limits their potential for widespread applications.Herein,we first present the synthesis of 2D lead-free halide perovskite (Cs_(3)Bi_(2)I_(9)) nanosheets with self-template-oriented method,in which BiOI/Bi_(2)O_(2) nanosheets were used as the template and Bi ion source simultaneously.Through facile electrostatic self-assembly strategy,a Z-scheme heterojunction composed of Cs_(3)Bi_(2)I_(9)nanosheets and CeO_(2) nanosheets (Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1) was constructed as photocatalyst for the photo-reduction of CO_(2) coupled with the oxidation of H_(2)O.Due to the matching energy levels and the close interfacial contact between Cs_(3)Bi_(2)I_(9)and CeO_(2) nanosheets,the separation efficiency of the photogenerated carriers in Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1 composite was significantly improved.Consequently,the environment-friendly halide perovskite heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1presents impressive photocatalytic activity for the reduction of CO_(2)to CH_(4)and CO with an electron consumption yield of 877.04μmol g^(-1),which is over 7 and 15 times higher than those of pristine Cs_(3)Bi_(2)I_(9)and CeO_(2)nanosheets,exceeding the yield of other reported bismuth-based perovskite for photocatalytic CO_(2)reduction.

Ligand-free CsPbBr_(3) with calliandra-like nanostructure for efficient artificial photosynthesis

The low-efficiency CO_(2) uptake capacity and insufficient photogenerated exciton dissociation of current metal halide perovskite(MHP)nanocrystals with end-capping ligands extremely restrict their application in the field of artificial photosynthesis.Herein,we demonstrate that ligand-free CsPbBr_(3) with calliandralike nanostructure(LF-CPB CL)can be synthesized easily through a ligand-free seed-assisted dissolutionrecrystallization growth process,exhibiting significantly enhanced CO_(2) uptake capacity.More specifically,the abundant surface bromine(Br)vacancies in ligand-free MHP materials are demonstrated to be beneficial to photogenerated carrier separation.The electron consumption rate of LF-CPB CL for photocatalytic CO_(2) reduction increases 7 and 20 times over those of traditional ligand-capping CsPbBr_(3)nanocrystal(L-CPB NC)and bulk CsPbBr_(3),respectively.Moreover,the absence of ligand hindrance can facilitate the interfacial electronic coupling between LF-CPB CL and tetra(4-carboxyphenyl)porphyrin iron(Ⅲ)chloride(Fe-TCPP)cocatalyst,bringing forth significantly accelerated interfacial charge separation.The LF-CPB CL/Fe-TCPP exhibits a total electron consumption rate of 145.6μmol g^(-1) h^(-1) for CO_(2)photoreduction coupled with water oxidation which is over 14 times higher than that of L-CPB NC/FeTCPP.

Synthesis of wafer-scale graphdiyne/graphene heterostructure for scalable neuromorphic computing and artificial visual systems

Graphdiyne(GDY)is emerging as a promising material for various applications owing to its unique structure and fascinating properties.However,the application of GDY in electronics and optoelectronics are still in its infancy,primarily owing to the huge challenge in the synthesis of large-area and uniform GDY film for scalable applications.Here a modified van der Waals epitaxy strategy is proposed to synthesize wafer-scale GDY film with high uniformity and controllable thickness directly on graphene(Gr)surface,providing an ideal platform to construct large-scale GDY/Gr-based optoelectronic synapse array.Essential synaptic behaviors have been realized,and the linear and symmetric conductance-update characteristics facilitate the implementation of neuromorphic computing for image recognition with high accuracy and strong fault tolerance.Logic functions including“NAND”and“NOR”are integrated into the synapse which can be executed in an optical pathway.Moreover,a visible information sensing-memory-processing system is constructed to execute real-time image acquisition,in situ image memorization and distinction tasks,avoiding the time latency and energy consumption caused by data conversion and transmission in conventional visual systems.These results highlight the potential of GDY in applications of neuromorphic computing and artificial visual systems.

Enhancing photocatalytic performance of metal-organic frameworks for CO_(2) reduction by a bimetallic strategy

Metal-organic frameworks(MOFs) as a type of crystalline heterogeneous catalysts have shown potential application in photocatalytic CO_(2)reduction.However,MOF catalysts with high efficiency and selectivity are still in pursuit.Herein,by a bimetallic strategy,the catalytic performance of a Co-MOF for photocatalytic CO_(2)reduction was enhanced.Specifically,the Co-MOF based on 4,5-dicarboxylic acid(H;IDC) and4,4’-bipydine(4,4’-bpy) can catalyze CO;reduction to CO,with high efficiency but relatively low selectivity.After replacement of 2/3 Co(Ⅱ) with Ni(Ⅱ) within Co-MOF,the resulted isostructural Co_(1)Ni_(2)-MOF not only retains high efficiency for photocatalytic CO_(2)reduction,but also shows enhanced CO selectivity.The CO evolution rate reaches 1160 μmol g^(-1)h^(-1)and the CO selectivity reaches as high as 94.6%.The enhanced photocatalytic CO_(2)reduction performance is supported by theoretical calculation results.This case demonstrates that bimetallic strategy is an effective mean to optimize the catalytic performance of MOF catalysts for photochemical CO_(2)reduction.

Structural regulation of single-atomic site catalysts for enhanced electrocatalytic CO_(2)reduction

Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is considered an efficient way to convert CO_(2)into high-value-added chemicals,and thus is of significant social and economic value.Metal single-atomic site catalysts(SASCs)generally have excellent selectivity because of their 100%atomic utilization and uniform structure of active sites,and thus promise a broad range of applications.However,SASCs still face challenges such as low intrinsic activity and low density of active sites.Precise regulation of the microstructures of SASCs is an effective method to improve their CO_(2)RR performance and to obtain deep reduction products.In this article,we systematically summarize the current research status of SASCs developed for highly efficient catalysis of CO_(2)RR,discuss the various structural regulation methods for enhanced activity and selectivity of SASCs for CO_(2)RR,and review the application of in-situ characterization technologies in the SASC-catalyzed CO_(2)RR.We then discuss the problems yet to be solved in this area,and propose the future directions of the research on the design and application of SASCs for CO_(2)RR.

Acetate-assistant efficient cation-exchange of halide perovskite nanocrystals to boost the photocatalytic CO_(2) reduction

The judicious implantation of active metal cations into the surface of semiconductor nanocrystal(NC)through cation-exchange is one of the facile and viable strategies to enhance the activity of catalysts for photocatalytic CO_(2)reduction,by shortening the transfer pathway of photogenerated carriers and increasing the active sites simultaneously.However,cation-exchange is hard to achieve for halide perovskite NCs owing to the stable octahedron of[PbX6]4−with strong interaction between halogen and lead.Herein,we report a facile method to overcome this obstacle by replacing partial Br−with acetate(Ac−)to generate CsPbBr_(3) NC(coded as CsPbBr_(3−x)Ac_(x)).A small amount of Ac−instead of Br−does not change the crystal structure of halide perovskite.Owing to the weaker interaction between acetate and lead in comparison with bromide,the corresponding octahedron structure containing acetate in CsPbBr_(3−x)Ac_(x) can be easily opened to realize efficient cation-exchange with Ni^(2+) ions.The resulting high loading amount of Ni^(2+) as active site endows CsPbBr_(3−x)Ac_(x) with an improved performance for photocatalytic CO_(2)reduction under visible light irradiation,exhibiting a significantly increased CO yield of 44.09μmol·g^(−1)·h^(−1),which is over 8 and 3 times higher than those of traditional pristine CsPbBr_(3) and nickel doped CsPbBr_(3) NC,respectively.This work provides a critical solution for the efficient metal doping of low-cost halide perovskite NCs to enhance their photocatalytic activity,promoting their practical applications in the field of photocatalysis.

Enhancing the photoelectrocatalytic performance of metal-free graphdiyne-based catalyst

As a new member of the carbon family,graphdiyne is an intrinsic semiconductor featuring a natural bandgap,which endues it potential for direct application in photoelectric devices.However,without cooperating with other active materials,conventional hexacetylene-benzene graphdiyne(HEB-GDY)shows poor performances in photocatalysis and photoelectric devices due to its non-ideal visible light absorption,low separation efficiency of the photogenerated carriers and insufficient sites for hydrogen production.Herein,we report a molecular engineering strategy for the regulation of GDY-based carbon materials,by incorporating a strong pyrene absorption group into the matrix of graphdiyne,to obtain pyrenyl graphdiyne(Pyr-GDY)nanofibers through a modified Glaser-Hay coupling reaction of 1,3,6,8-tetraethynylpyrene(TEP)monomers.For comparison,phenyl graphdiyne(Phe-GDY)nanosheets were also constructed using 1,3,4,6-tetraethynylbenzene(TEB)as a monomer.Compared with Phe-GDY,Pyr-GDY exhibits a wider visible light absorption band,promoted efficiency of the charge separation/transport and more sufficient active sites for water reduction.As a result,Pyr-GDY alone displays superior photoelectrocatalytic performance for water splitting,giving a cathode photocurrent density of^138μA cm-2 at a potential of-0.1 Vversus normal hydrogen electrode(NHE)in neutral aqueous solution,which is almost ten and twelve times as high as those of Phe-GDY(14μA cm-2)and HEB-GDY(12μA cm-2),respectively.Such a performance is also superior to those of most reported carbonbased metal-free photocathode.The results of theoretical calculations reveal that the carbon atoms in the acetylene bonds are the active sites for proton reduction.This work offers a new strategy for the construction of graphdiyne-based metal-free photoelectrocatalysts with enhanced photoelectrocatalytic performance.

Lattice-matched in-situ construction of 2D/2D T-SrTiO_(3)/CsPbBr_(3) heterostructure for efficient photocatalysis of CO_(2) reduction

The elaborate regulation of heterostructure interface to accelerate the interfacial charge separation is one of practicable approaches to improve the photocatalytic CO_(2)reduction performance of halide perovskite(HP) materials. Herein, we report an in-situ growth strategy for the construction of 2D CsPbBr_(3)based heterostructure with perovskite oxide(SrTiO_(3)) nanosheet as substrate(CsPbBr_(3)/SrTiO_(3)). Lattice matching and matchable energy band structures between CsPbBr_(3)and SrTiO_(3)endow CsPbBr_(3)/SrTiO_(3)heterostructure with an efficient interfacial charge separation. Moreover, the interfacial charge transfer rate can be further accelerated by etching SrTiO_(3)with NH_(4)F to form flat surface capped with Ti-O bonds. The resultant 2D/2D T-SrTiO_(3)/CsPbBr_(3)heterostructure exhibits an impressive photocatalytic activity for CO_(2)conversion with a CO yield of 120.2 ± 4.9 μmol g^(-1)h^(-1)at the light intensity of 100 m W/cm^(2)and water as electron source, which is about 10 and 7 times higher than those of the pristine SrTiO_(3)and CsPbBr_(3)nanosheets, surpassing the reported halide perovskite-based photocatalysts under the same conditions.

Engineering Coordination Environment of Cobalt Center in Molecular Catalysts for Improved Photocatalytic CO_(2) Reduction

The creation of effective and inexpensive catalysts is essential for photocatalytic CO_(2) reduction.Homogeneous molecular catalysts,possessing definite crystal structures,are desirable to study the relationship between catalytic performance and coordination microenvironment around catalytic center.In this report,we elaborately developed three Co(II)-based molecular catalysts with different coordination microenvironments for CO_(2) reduction,named[CoN_(3)O]ClO_(4),[CoN_(4)]ClO_(4),and[CoN_(3)S]ClO_(4),respectively.The optimal[CoN_(3)O]ClO_(4) photocatalyst has a maximum TON of 5652 in photocatalytic reduced CO_(2) reduction,which is 1.28 and 1.65 times greater than that of[CoN_(4)]ClO_(4) and[CoN_(3)S]ClO_(4),respectively.The high electronegativity of oxygen in L1(N,N-bis(2-pyridylmethyl)-N-(2-hydroxybenzyl)amine)provides the Co(II)catalytic centers with low reduction potentials and a more stable*COOH intermediate,which facilitates the CO_(2)-to-CO conversion and accounts for the high photocatalytic activity of[CoN_(3)O]ClO_(4).This work provides researchers new insights in development of catalysts for photocatalytic CO_(2) reduction.

In-situ growth of PbI_(2) on ligand-free FAPbBr_(3) nanocrystals to significantly ameliorate the stability of CO_(2) photoreduction

Excellent optical properties involving strong visible light response and superior carrier transport endow metal halide perovskites(MHP)with a fascinating prospect in the field of photocatalysis.Nevertheless,the poor stability of MHP nanocrystals(NCs)in water-contained system,especially without the protection of long alkyl chain ligands,severely restricts their photocatalytic performance.In this context,we report an effortless strategy for the generation of ligand-free MHP NCs based photocatalyst with high water tolerance,by coating PbI_(2)on the surface of ligand-free formamidinium lead bromide(FAPb Br_(3))NCs via the facile procedure of in-situ conversion with the aid of ZnI_(2).Under the protection of PbI_(2)layer,the resultant FAPb Br_(3)/PbI_(2)composite exhibits significantly ameliorated stability in an artificial photosynthesis system with CO_(2)and H_(2)O vapor as feedstocks.Moreover,the formation of compact PbI_(2)layer can accelerate the separation of photogenerated carriers in FAPbBr_(3)NCs,bringing forth a remarkable improvement of CO_(2)photoreduction efficiency with an impressive electron consumption yield of 2053μmol/g in the absence of organic sacrificial agents,which is 7-fold over that of pristine FAPb Br_(3)NCs.

Cobalt-based heterogeneous catalysts for photocatalytic carbon dioxide reduction

Solar light-driven CO_(2)reduction to high value-added chemicals has considered as an outstanding way to solve energy crisis and climate warming.Recently,various photocatalysts have been developed to achieve this reaction.Among them,cobaltbased heterogeneous catalysts have attracted great interest because of their promising performance,product selectivity and stability.Herein,we systematically summarize the research progress of various cobalt-based heterogeneous catalysts for the photoreduction of CO_(2),such as single-atom cobalt,and cobalt-based oxides,nitrides,sulfi des,phosphides,metal-organic frameworks and covalent-organic frameworks.Meanwhile,the advantages and structure-activity relationship of these catalysts in photocatalytic CO_(2)reduction reaction are discussed.Finally,the challenges and prospects for constructing cobaltbased heterogeneous catalysts with high effi ciency are highlighted.

Surface iodine and pyrenyl-graphdiyne co-modified Bi catalysts for highly efficient CO_(2) electroreduction in acidic electrolyte

CO_(2) electroreduction to formic acid/formate would contribute to alleviating the energy and climate crisis.This work reports a Bi-based catalyst derived from the in-situ electroreduction of Bi_(2)O_(2)CO_(3) modified with iodine and pyrenyl-graphdiyne(PGDY)on the surface for efficient electroreduction of CO_(2) in acidic electrolyte,with a high partial current density of 98.71 mA·cm^(-2) and high Faradaic efficiency(FE)>90%over the potential range from^(-1).2 to-1.5 V vs.reversible hydrogen electrode(RHE),as well as the long-term operational stability over 240 h without degradation in H-type cell.Experimental results and density function theory calculations show that the synergistic effect of surface iodine and PGDY is responsible for this active and extremely stable process of CO_(2) electroreduction via lowering the energy barriers for formation of*OCHO intermediate,suppressing the competitive HER by enhancing the concentration of both K+and CO_(2) at reaction interface,as well as preventing the dissolution and re-deposition of active Bi atoms on surface during catalytic reaction.This work provides new insight into designing highly active and stable electrocatalysts for CO_(2) reduction.

Diatomic Pd catalyst with conjugated backbone for synergistic electrochemical CO_(2)reduction

Double-site catalysts have attracted widespread attention in the field of electrocatalysis due to their high metal loading,adjustable active centres,and electronic valence states.However,the development of bimetallic sites catalysts that coordinate with definite atoms is still in the exploratory stage.Here,we designed and synthesized a bimetallic palladium complex(BPB-Pd_(2))with conjugated backbone.The supported BPB-Pd_(2)was applied to electrochemical CO_(2)reduction reaction(CO_(2)RR)for the first time.The as-obtained BPB-Pd_(2)gives an exceptional Faradaic efficiency of CO(FECO)of 94.4%at−0.80 V vs.reversible hydrogen electrode(RHE),which is significantly superior to monoatomic palladium catalyst(BPB-Pd1).The density functional theory(DFT)calculations revealed that the essential reason for the outstanding activity of BPB-Pd_(2)toward CO_(2)RR was that the electronic effect between diatomic palladium reduces the free energy change for CO_(2)RR process.Thus,BPB-Pd_(2)exhibits moderate free energy change to form COOH*intermediate,which was beneficial for the generation of CO in CO_(2)RR.

The Sb-N charge transfer bridge over Cs_(3)Sb_(2)Br_(9)/Sb-C_(3)N_(4)Z-scheme heterojunction for boosting photocatalytic CO_(2)reduction

Developing highly efficient heterostructural photocatalysts for direct CO_(2)reduction coupled with water oxidation remains challenging,the key to which is to establish an efficient interfacial charge transport channel.Herein,we present a Cs_(3)Sb_(2)Br_(9)/Sb–C_(3)N_(4)Z-scheme heterojunction prepared with an in-situ growth method based on the Sb atomic pinning effect.As revealed by the analysis of experimental and theoretical calculation results,the introduction of Sb anchors on C_(3)N_(4)leads to the formation of an Sb–N charge transfer bridge between Cs_(3)Sb_(2)Br_(9)and C_(3)N_(4),promoting interfacial charge communication over Cs_(3)Sb_(2)Br_(9)/Sb–C_(3)N_(4)heterojunction.Moreover,it can induce the heterojunction interfacial charge transfer pathway between Cs_(3)Sb_(2)Br_(9)and C_(3)N_(4)to change from type II to the type Z-scheme,enabling the change of the catalytic site from C_(3)N_(4)to Cs_(3)Sb_(2)Br_(9),thus promoting the CO_(2)activation.As a result,Cs_(3)Sb_(2)Br_(9)/Sb–C_(3)N_(4)achieves efficient CO_(2)to CO photocatalytic conversion using water as the electron source under simulated solar light irradiation(100 mW·cm^(−2)),with the yield of 198.4μmol·g^(−1)·h^(−1),which is nearly 3-fold and 9-fold over the counterpart synthesized catalyst without Sb anchors(Cs_(3)Sb_(2)Br_(9)/g–C_(3)N_(4))and pure g–C_(3)N_(4),respectively.This work provides a new alternative solution for the design of highly efficient heterojunction photocatalysts.

Graphdiyene enables ultrafine Cu nanoparticles to selectively reduce CO_(2) to C_(2+)products

Reducing the size of heterogeneous nanocatalysts is generally conducive to improving their atomic utilization and activities in various catalytic reactions.However,this strategy has proven less effective for Cu-based electrocatalysts for the reduction of CO_(2) to multicarbon(O2+)products,owing to the overly strong binding of intermediates on small-sized(<15 nm)Cu nanoparticles(NPs).Herein,by incorporating pyreny-graphdiyne(Pyr-GDY),we successfully endowed ultrafine(〜2 nm)Cu NPs with a significantly elevated selectivity for CO_(2)-to-C_(2+)conversion.The Pyr-GDY can not only help to relax the overly strong binding between adsorbed H*and CO*intermediates on Cu NPs by tailoring the d-band center of the catalyst,but also stabilize the ultrafine Cu NPs through the high affinity between alkyne moieties and Cu NPs.The resulting Pyr-GDY-Cu composite catalyst gave a Faradic efficiency(FE)for C2+products up to 74%,significantly higher than those of support-free Cu NPs(C2+FE.〜2%),carbon nanotube-supported Cu NPs(CNT-Cu,C_(2+)FE,〜18%),graphene oxide-supported Cu NPs(GO-Cu,C_(2+)FE,〜8%),and other reported ultrafine Cu NPs.Our results demonstrate the critical influence of graphdiyne on the selectivity of Cu-catalyzed CO_(2) electroreduction,and showcase the prospect for ultrafine Cu NPs catalysts to convert CO_(2) into value-added C_(2+)products.

Decorating graphdiyne on ultrathin bismuth subcarbonate nanosheets to promote CO_(2)electroreduction to formate

Electrocatalytic reduction of CO_(2)is one of the most attractive approaches for converting CO_(2)into valuable chemical feedstocks and fuels.This work reports a catalyst comprising graphdiyne-decorated bismuth subcarbonate(denoted as BOC@GDY)for efficient electroreduction of CO_(2)to formate.The BOC@GDY shows a stable current density of 200 mA cm^(-2)at–1.1 V in a flow cell configuration,with a faradaic efficiency of 93.5%for formate.Experimental results show that the synergistic effect in BOC@GDY is beneficial for the CO_(2)adsorption affinity,the reaction kinetics and the selectivity for formate.In addition,in-situ X-ray absorption and Raman spectroscopy indicate that the electron-rich GDY could facilitate the reduction from Bi(Ⅲ)to Bi(0),thus leading to more active sites.We also demonstrate that the promoting effect of GDY in CO_(2)electroreduction can be further extended to other metal catalysts.To the best of our knowledge,such general promoting functions of GDY for CO_(2)electroreduction have not been documented thus far.

Iron sites on defective BiOBr nanosheets:Tailoring the molecular oxygen activation for enhanced photocatalytic organic synthesis

Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simultaneously tailor the charge kinetics and promote reactant chemisorption on semiconductor catalysts for enhanced photocatalytic performance.Herein,we report iron sites immobilized on defective BiOBr nanosheets as an efficient and selective photocatalyst for activation of O_(2) to singlet oxygen(^(1)O_(2)).These Fe^(3+) species anchored by oxygen vacancies can not only facilitate the separation and migration of photogenerated charge carrier,but also serve as active sites for effective adsorption of 02.Moreover,low-temperature phosphorescence spectra combined with X-ray photoelectron spectroscopy(XPS)and electronic paramagnetic resonance(EPR)spectra under illumination reveal that the Fe species can boost the quantum yield of excited triplet state and accelerate the energy transfer from excited triplet state to adsorbed O2 via a chemical loop of Fe^(3+)/Fe^(2+),thereby achieving highly efficient and selective generation of ^(1)O_(2).As a result,the versatile iron sites on defective BiOBr nanosheets contributes to near-unity conversion rate and selectivity in both aerobic oxidative coupling of amines to imines and sulfoxidation of organic sulfides.This work highlights the significant role of metal sites anchored on semiconductors in regulating the charge/energy transfer during the heterogeneous photocatalytic process,and provides a new angle for designing high-performance photocatalysts.

Optically modulated dual-mode memristor arrays based on core-shell CsPbBr_(3)@graphdiyne nanocrystals for fully memristive neuromorphic computing hardware

Artificial synapses and neurons are crucial milestones for neuromorphic computing hardware,and memristors with resistive and threshold switching characteristics are regarded as the most promising candidates for the construction of hardware neural networks.However,most of the memristors can only operate in one mode,that is,resistive switching or threshold switching,and distinct memristors are required to construct fully memristive neuromorphic computing hardware,making it more complex for the fabrication and integration of the hardware.Herein,we propose a flexible dual-mode memristor array based on core–shell CsPbBr3@graphdiyne nanocrystals,which features a 100%transition yield,small cycle-to-cycle and device-to-device variability,excellent flexibility,and environmental stability.Based on this dual-mode memristor,homo-material-based fully memristive neuromorphic computing hardware—a power-free artificial nociceptive signal processing system and a spiking neural network—are constructed for the first time.Our dual-mode memristors greatly simplify the fabrication and integration of fully memristive neuromorphic systems.

Low-loading gold in situ doped with sulfur by biomolecule-assisted approach for promoted electrochemical carbon dioxide reduction

For electrochemical carbon dioxide reduction(CO_(2)RR),CO_(2)-to-CO conversion is considered an ideal route towards carbon neutrality for practical applications.Gold(Au)is known as a promising catalyst with high selectivity for CO;however,it suffers from high cost and low mass-specific activity.In this study,we design and prepare a catalyst featuring uniform S-doped Au nanoparticles on N-doped carbon support(denoted as S-Au/NC)by an in situ synthesis strategy using biomolecules.The S-Au/NC displays high activity and selectivity for CO in CO_(2)RR with a Au loading as low as 0.4 wt.%.The Faradaic efficiency of CO(FECO)for S-Au/NC is above 95%at−0.75 V(vs.RHE);by contrast,the FECO of Au/NC(without S)is only 58%.The Tafel slope is 77.4 mV·dec−1,revealing a favorable kinetics process.Furthermore,S-Au/NC exhibits an excellent long-term stability for CO_(2)RR.Density functional theory(DFT)calculations reveal that the S dopant can boost the activity by reducing the free energy change of the potential-limiting step(formation of the*COOH intermediate).This work not only demonstrates a model catalyst featuring significantly reduced use of noble metals,but also establishes an in situ synthesis strategy for preparing high-performance catalysts.