氮掺杂石墨烯负载过渡金属催化CO_(2)RR的DFT研究

设计了氮掺杂石墨烯负载四种过渡金属单原子催化剂用于CO_(2)RR(金属为Cu、Rh、Ir、Mn),考虑了5种氮配位(N_(1)、N_(2-1)、N_(2-2)、N_(3)和N_(4)),并通过第一性原理研究反应机理。自由能曲线显示Ir-N_(4)具有-0.323e V的低极限电位,通过增加缺陷改性的Rh-N_(4)的CO_(2)RR性能也得到了改善。进一步通过Ir-N_(4)和Rh-N_(4)的差分电荷和态密度曲线分析吸附中间体COOH和金属原子之间的电荷转移和键合状态,发现金属原子和COOH之间的强烈相互作用形成了共价键,从而降低反应的总能量。本研究为设计高效的单原子CO_(2)RR催化剂提供了理论参考。

Cu_(4)SnS_(4)的制备及其电催化还原CO_(2)性能的研究

通过溶剂热法合成三元硫属化合物CTS(Cu_(4)SnS_(4)).利用X-射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、电化学阻抗(EIS)、电化学活性表面积(ECSA)、塔菲尔斜率(Tafel)等对样品的结构、形貌和电催化还原CO_(2)(CO_(2)RR)性能进行了探究.实验结果表明,Cu_(4)SnS_(4)电催化还原CO_(2)的能力比相应的二元金属化合物SnS_(2),Cu_(2)S和Cu_(10)Sn_(3)材料明显提升.其中200℃、24 h制备的纯相Cu_(4)SnS_(4)催化剂性能最好,在-1.0 V(vs.RHE)电位下,电流密度稳定可达到18 mA/cm^(2),甲酸盐的选择性高达75%.

镍单原子催化剂的制备及其电催化CO_(2)还原研究

电催化CO_(2)还原反应(Electrocatalytic CO_(2)reduction reaction, CO_(2)RR)在解决全球变暖和能源危机方面有着巨大的应用潜力,但目前催化效率低、催化产物多样等问题限制了CO_(2)RR反应的商业化应用。采用一锅法、碳化法制备了一系列不同镍含量的镍单原子催化剂,利用XRD、XPS、ICP-OES、HRTEM、HAADF-STEM、XAS等方法对镍单原子催化剂的形貌结构、原子价态、金属含量等方面进行表征,并通过电催化还原产物的法拉第效率(Faraday efficiency, FE)和电流密度(Current density,J)来评价其电催化性能。此外,还研究了电解实验装置的改变对升电催化性能的提升。实验结果表明,随着Ni单原子催化剂的Ni金属负载量增加,产物CO的FECO和JCO均增加。催化剂中Zn1Ni2-CN表现出了优异的CO_(2)RR催化性能,在H型电解池中,在-0.7 V vs. RHE电位下FECO达到89%,在-0.9 V vs. RHE下JCO达到6.99 mA·cm^(-2)。在流动电解池中,大范围电位变化下(-0.4~-1.2 V vs. RHE)FECO均保持在99%以上,且在-1.2 V vs. RHE电位下产物电流密度JCO达到174.5 mA·cm^(-2)。

Plasma-assisted synthesis of porous bismuth nanosheets for electrocatalytic CO_(2)-to-formate reduction

The electrochemical carbon dioxide reduction(eCO_(2)RR)to formate,driven by clean energy,is a promising approach for producing renewable chemicals and high-value fuels.Despite its potential,further development faces challenges due to limitations in electrocatalytic activity and durability,especially for nonnoble metal-based catalysts.Here,naturally abundant bismuth-based nanosheets that can effectively drive CO_(2)-to-formate electrocatalytic reduction are prepared using the plasma-activated Bi_(2)Se_(3) followed by a reduction process.Thus-obtained plasma-activated Bi nanosheets(P-BiNS)feature ultrathin structures and high surface areas.Such nanostructures ensure the P-BiNS with outstanding eCO_(2)RR catalytic performance,highlighted by the current density of over 80 mA cm^(-2) and a formate Faradic efficiency of>90%.Furthermore,P-BiNS catalysts demonstrate excellent durability and stability without deactivation following over 50h of operation.The selectivity for formate production is also studied by density functional theory(DFT)calculations,validating the importance and efficacy of the stabilization of intermediates(^(*)OCHO)on the P-BiNS surfaces.This study provides a facile plasma-assisted approach for developing high-performance and low-cost electrocatalysts.

Cu-based materials for electrocatalytic CO_(2) to alcohols:Reaction mechanism,catalyst categories,and regulation strategies

Electrocatalytic CO_(2) reduction reaction(CO_(2)RR)technology,which enables carbon capture storage and resource utilization by reducing CO_(2) to valuable chemicals or fuels,has become a global research hotspot in recent decades.Among the many products of CO_(2)RR(carbon monoxide,acids,aldehydes and alcohols,olefins,etc.),alcohols(methanol,ethanol,propanol,etc.)have a higher market value and energy density,but it is also more difficult to produce.Copper is known to be effective in catalyzing CO_(2) to high valueadded alcohols,but with poor selectivity.The progress of Cu-based catalysts for the selective generation of alcohols,including copper oxides,bimetals,single atoms and composites is reviewed.Meanwhile,to improve Cu-based catalyst activity and modulate product selectivity,the modulation strategies are straighten out,including morphological regulation,crystalline surface,oxidation state,as well as elemental doping and defect engineering.Based on the research progress of electrocatalytic CO_(2) reduction for alcohol production on Cu-based materials,the reaction pathways and the key intermediates of the electrocatalytic CO_(2)RR to methanol,ethanol and propanol are summarized.Finally,the problems of traditional electrocatalytic CO_(2)RR are introduced,and the future applications of machine learning and theoretical calculations are prospected.An in-depth discussion and a comprehensive review of the reaction mechanism,catalyst types and regulation strategies were carried out with a view to promoting the development of electrocatalytic CO_(2)RR to alcohols.

A general descriptor for guiding the electrolysis of CO_(2)in molten carbonate

Molten carbonate is an excellent electrolyte for the electrochemical reduction of CO_(2)to carbonaceous materials.However,the electrolyte–electrode-reaction relationship has not been well understood.Herein,we propose a general descriptor,the CO_(2)activity,to reveal the electrolyte–electrode-reaction relationship by thermodynamic calculations and experimental studies.Experimental studies agree well with theoretical predictions that both cations(Li^(+),Ca^(2+),Sr^(2+)and Ba^(2+))and anions(BO_(2)^(-),Ti_(5)O_(14)^(8-),SiO_(3)^(2-))can modulate the CO_(2)activity to control both cathode and anode reactions in a typical molten carbonate electrolyzer in terms of tuning reaction products and overpotentials.In this regard,the reduction of CO_(3)^(2-)can be interpreted as the direct reduction of CO_(2)generated from the dissociated CO_(3)^(2-),and the CO_(2)activity can be used as a general descriptor to predict the electrode reaction in molten carbonate.Overall,the CO_(2)activity descriptor unlocks the electrolyte–electrode-reaction relationship,thereby providing fundamental insights into guiding molten carbonate CO_(2)electrolysis.

Enhanced photocatalytic CO_(2)reduction performance in Nidoped perovskite nanocrystals controlled by magnetic fields

In recent years,magnetic fields have been widely applied in catalysis to increase the performance of electrocatalysis,photocatalysis,and thermocatalysis through an important noncontact way.This work demonstrated that doping CsPbCl_(3) halide perovskite nanocrystals with nickel ions(Ni2+)and applying an external magnetic field can significantly enhance the performance of the photocatalytic carbon dioxide reduction reaction(CO_(2)RR).Compared with its counterpart,Ni-doped CsPbCl_(3) exhibits a sixfold increase in CO_(2)RR efficiency under a 500 mT magnetic field.Insights into the mechanism of this enhancement effect were obtained through photogenerated current density measurements and X-ray magnetic circular dichroism.The results illustrate that the significant enhancement in catalytic performance by the magnetic field is attributed to the synergistic effects of magnetic element doping and the external magnetic field,leading to reduced electron‒hole recombination and extended carrier lifetimes.This study provides an effective strategy for enhancing the efficiency of the photocatalytic CO_(2)RR by manipulating spin-polarized electrons in photocatalytic semiconductors via a noncontact external magnetic field.

Porous Indium Nanocrystals on Conductive Carbon Nanotube Networks for High-Performance CO_(2)-to-Formate Electrocatalytic Conversion

Ever-increasing emissions of anthropogenic carbon dioxide(CO_(2))cause global environmental and climate challenges.Inspired by biological photosynthesis,developing effective strategies NeuNlto up-cycle CO_(2)into high-value organics is crucial.Electrochemical CO_(2)reduction reaction(CO_(2)RR)is highly promising to convert CO_(2)into economically viable carbon-based chemicals or fuels under mild process conditions.Herein,mesoporous indium supported on multi-walled carbon nanotubes(mp-In@MWCNTs)is synthesized via a facile wet chemical method.The mp-In@MWCNTs electrocatalysts exhibit high CO_(2)RR performance in reducing CO_(2)into formate.An outstanding activity(current density-78.5 mA cm^(-2)),high conversion efficiency(Faradaic efficiency of formate over 90%),and persistent stability(∼30 h)for selective CO_(2)-to-formate conversion are observed.The outstanding CO_(2)RR process performance is attributed to the unique structures with mesoporous surfaces and a conductive network,which promote the adsorption and desorption of reactants and intermediates while improving electron transfer.These findings provide guiding principles for synthesizing conductive metal-based electrocatalysts for high-performance CO_(2)conversion.

纳米结构石墨相氮化碳用于CO_(2)催化转化的研究进展

系统性地梳理了石墨相氮化碳(g-C_(3)N_(4))在光/电催化二氧化碳还原反应(CO_(2)RR)的最新研究进展,深入探讨了通过精细调控其局域电子结构、表面化学配位、电荷传输机制及光学特性等关键参数所实现的催化性能提升。具体策略涵盖了结构优化设计、缺陷工程引入、元素/分子掺杂策略以及异质结构构建等前沿技术,这些创新方法为g-C_(3)N_(4)催化剂的定制化设计提供了丰富的工具箱。最后,对面临的挑战和前景进行了简要的总结和展望,以期为进一步合理设计g-C_(3)N_(4)作为选择性高效的CO_(2)RR催化剂。

Polypyrrole reinforced ZIF-67 with modulated facet exposure and billion-fold electrical conductivity enhancement towards robust photocatalytic CO_(2) reduction

The implementation of metal organic frameworks(MOFs) as the co-catalysts in hybrid photocatalytic systems puts requirements on both their charge-carrying capability and solvent stability. In the current study, in order to simultaneously promote the electrical conductivity and water stability of ZIF-67, an insitu monomer trapping strategy is deployed to synthesize polypyrrole(PPy)-reinforced ZIF-67 ensembles.Through coordination modulation, the incremental addition of pyrrole monomers enables to alter the crystal morphology of ZIF-67 from rhombic dodecahedra to truncated rhombic dodecahedra, and further to cubes. Upon polymerization, the resulted composite, in comparison to ZIF-67, demonstrates a billionfold conductivity enhancement, much improved chemical stability in pronated solvents, as well as largely retained specific surface area and porosity, enabling it functioning as an outstanding co-catalyst for catalyzing robust photocatalytic CO_(2) reduction. Furthermore, a PPy-mediated electron harvest and relay mechanism is proposed for rationalizing the enhanced photocatalytic performance.

Transition metal-based single-atom catalysts(TM-SACs);rising materials for electrochemical CO_(2) reduction

The continuous increase of global atmospheric CO_(2) concentrations brutally damages our environment. A series of methods have been developed to convert CO_(2) to valuable fuels and value-added chemicals to maintain the equilibrium of carbon cycles. The electrochemical CO_(2) reduction reaction(CO_(2)RR) is one of the promising methods to produce fuels and chemicals, and it could offer sustainable paths to decrease carbon intensity and support renewable energy. Thus, significant research efforts and highly efficient catalysts are essential for converting CO_(2) into other valuable chemicals and fuels. Transition metal-based single atoms catalysts(TM-SACs) have recently received much attention and offer outstanding electrochemical applications with high activity and selectivity opportunities. By taking advantage of both heterogeneous and homogeneous catalysts, TM-SACs are the new rising star for electrochemical conversion of CO_(2) to the value-added product with high selectivity. In recent years, enormous research effort has been made to synthesize different TM-SACs with different M–Nxsites and study the electrochemical conversion of CO_(2) to CO. This review has discussed the development and characterization of different TMSACs with various catalytic sites, fundamental understanding of the electrochemical process in CO_(2) RR,intrinsic catalytic activity, and molecular strategics of SACs responsible for CO_(2)RR. Furthermore, we extensively review previous studies on 1 st-row transition metals TM-SACs(Ni, Co, Fe, Cu, Zn, Sn) and dual-atom catalysts(DACs) utilized for electrochemical CO_(2) conversions and highlight the opportunities and challenges.

Charge transfer and orbital reconstruction of non‐noble transition metal single‐atoms anchored on Ti_(2)CT_(x)‐MXenes for highly selective CO_(2) electrochemical reduction

Inspired by MXene nanosheets and their regulation of surface functional groups,a series of Ti_(2)C‐based single‐atom electrocatalysts(TM@Ti_(2)CT_(x),TM=V,Cr,Mn,Fe,Co,and Ni)with two dif‐ferent functional groups(T=–O and–S)was designed.The CO_(2)RR catalytic performance was stud‐ied using well‐defined ab initio calculations.Our results show that the CO_(2) molecule can be more readily activated on TM@Ti_(2)CO_(2) than the TM@Ti_(2)CS_(2) surface.Bader charge analysis reveals that the Ti_(2)CO_(2) substrate is involved in the adsorption reaction,and enough electrons are injected into the 2π*u orbital of CO_(2),leading to a V‐shaped CO_(2) molecular configuration and partial negative charge distribution.The V‐shaped CO_(2) further reduces the difficulty of the first hydrogenation reac‐tion step.The calculatedΔG of the first hydrogenation reaction on TM@Ti_(2)CO_(2) was significantly lower than that of the TM@Ti_(2)CS_(2) counterpart.However,the subsequent CO_(2) reduction pathways show that the UL of the potential determining step on TM@Ti_(2)CS_(2) is smaller than that of TM@Ti_(2)CO_(2).Combining the advantages of both TM@Ti_(2)CS_(2) and TM@Ti_(2)CO_(2),we designed a mixed functional group surface with–O and–S to anchor TM atoms.The results show that Cr atoms an‐chored on the surface of mixed functional groups exhibit high catalytic activity for the selective production of CH4.This study opens an exciting new avenue for the rational design of highly selec‐tive MXene‐based single‐atom CO_(2)RR electrocatalysts.

Enhanced electrocatalytic activity of iron amino porphyrins using a flow cell for reduction of CO_(2) to CO

The flexibility of molecular catalysts is highly coveted for the electrochemical reduction of carbon dioxide(CO_(2)) to carbon monoxide(CO) in both homogeneous and heterogeneous systems.While the electrocatalytic activity of molecular catalysts has been widely studied in H-cells;their less studied capabilities in more efficient flow cell reactors have the potential to rival that of heterogeneous catalysts.In this work,a comparative study of amino functionalized iron-tetraphenylporphyrins(amino-Fe-TPPs) immobilized onto carbonaceous materials in both H-cells and flow cells was conducted to selectively reduce CO_(2) to CO.In a flow cell set up operating in alkaline media,the resulting hybrid catalyst exhibits 87% faradaic efficiency(FE) with extraordinary current density(j) of 119 mA/cm^(2) and turnover frequency(TOF) of 14 s^(-1) at-1.0 V vs.RHE.This remarkable catalytic activity was achieved through thoughtful combination of molecular and flow cell design that provides an effective strategy for future immobilized heterogeneous approaches toward CO_(2) reduction reactions(CO_(2) RRs).

Metal oxides heterojunction derived Bi-In hybrid electrocatalyst for robust electroreduction of CO_(2) to formate

Electrochemical reduction of Bi-based metal oxides is regarded as an effective strategy to rationally design advanced electrocatalysts for electrochemical CO_(2)reduction reaction(CO_(2)RR).Realizing high selectivity at high current density is important for formate production,but remains challenging.Herein,the BiIn hybrid electrocatalyst,deriving from the Bi2O3/In2O3heterojunction(MOD-Biln),shows excellent catalytic performance for CO_(2)RR.The Faradaic efficiency of formate(FEHCOO-) can be realized over 90% at a wide potential window from-0.4 to-1.4 V vs.RHE,while the partial current density of formate(jHCOO-) reaches about 136.7 mA cm^(-2)at-1.4 V in flow cell without IR-compensation.In additio n,the MOD-Biln exhibits superior stability with high selectivity of formate at 100 mA cm^(-2).Systematic characterizations prove the optimized catalytic sites and interface charge transfer of MOD-Biln,while theoretical calculation confirms that the hybrid structure with dual Bi/In metal sites contribute to the optimal free energy of*H and*OCHO intermediates on MOD-Biln surface,thus accelerating the formation and desorption step of*HCOOH to final formate production.Our work provides a facile and useful strategy to develop highly-active and stable electrocatalysts for CO_(2)RR.

Surface modification of Cu_(2)O with stabilized Cu^(+) for highly efficient and stable CO_(2) electroreduction to C_(2+) chemicals

Copper(Cu)-based materials are known as the most attractive catalysts for electrochemical carbon dioxide reduction reaction(CO_(2)RR),especially the Cu^(+) species(e.g.,Cu_(2)O),which show excellent capability for catalyzing CO_(2) to C_(2+) chemicals because of their unique electronic structure.However,the active Cu^(+) species are prone to be reduced to metallic Cu under an electroreduction environment,thus resulting in fast deactivation and poor selectivity.Here,we developed an advanced surface modification strategy to maintain the active Cu^(+) species via assembling a protective layer of metal-organic framework(copper benzenetricarboxylate,CuBTC) on the surface of Cu_(2)O octahedron(Cu_(2)O@CuBTC).It's encouraging to see that the Cu_(2)O@CuBTC heterostructure outperforms the bare Cu_(2)O octahedron in catalyzing CO_(2) to C_(2+) chemicals and dramatically enhances the ratio of C_(2)H_(4)/CH_(4) products.A systematic study reveals that the introduced CuBTC shell plays a critical role in maintaining the active Cu^(+) species in Cu_(2)O@CuBTC heterostructure under reductive conditions.This work offers a practical strategy for improving the catalytic performance of CO_(2)RR over copper oxides and also establishes a route to maintain the state of valence-sensitive catalysts.

Atomic Cu Sites Engineering Enables Efficient CO_(2)Electroreduction to Methane with High CH_(4)/C_(2)H_(4)Ratio

Electrochemical reduction of CO_(2)into high-value hydrocarbons and alcohols by using Cu-based catalysts is a promising and attractive technology for CO_(2)capture and utilization,resulting from their high catalytic activity and selectivity.The mobility and accessibility of active sites in Cubased catalysts significantly hinder the development of efficient Cu-based catalysts for CO_(2)electrochemical reduction reaction(CO_(2)RR).Herein,a facile and effective strategy is developed to engineer accessible and structural stable Cu sites by incorporating single atomic Cu into the nitrogen cavities of the host graphitic carbon nitride(g-C_(3)N_(4))as the active sites for CO_(2)-to-CH_(4)conversion in CO_(2)RR.By regulating the coordination and density of Cu sites in g-C_(3)N_(4),an optimal catalyst corresponding to a one Cu atom in one nitrogen cavity reaches the highest CH_(4)Faraday efficiency of 49.04%and produces the products with a high CH_(4)/C_(2)H_(4)ratio over 9.This work provides the first experimental study on g-C_(3)N_(4)-supported single Cu atom catalyst for efficient CH_(4)production from CO_(2)RR and suggests a principle in designing highly stable and selective high-efficiency Cu-based catalysts for CO_(2)RR by engineering Cu active sites in 2D materials with porous crystal structures.

电催化CO_(2)还原立方体Cu_(2)O催化剂的制备及其在大面积膜电极反应器中的应用

电化学二氧化碳还原反应(carbon dioxide reduction reaction,CO_(2)RR)产乙烯目前已成为电催化CO_(2)RR领域的研究重点和热点.通过简单的化学沉淀耦合化学还原保护法成功获得了富含(111)晶面的立方体结构Cu_(2)O催化剂,系统研究了其在H型反应器以及零间距膜电极组件(membrane electrode assembly,MEA)反应器中的电化学性能.结果表明.富含(111)晶面的立方体结构Cu_(2)O催化剂表现出了优异的产乙烯活性;相比于H型反应器,零间距MEA反应器进行CO_(2)RR时的最佳法拉第效率(Faradaic efficiency,FE)提升了13.94%,总电流密度也基本可以满足工业化的需求(>200 mA/cm^(2));设计并组装的大面积(25 cm^(2))零间距MEA反应器在CO_(2)RR中表现出了优异的催化性能,且在槽压大于2.9 V时表现出了独特的“面积效应”.“面积效应”的出现表明零极距MEA反应器在有效面积放大时,除电极面积、电解质浓度、CO_(2)流速等关键因素的调控外,极板的流道设计、导电性优化等均可能会影响催化反应的电流密度.

Pause electrolysis for acidic CO_(2) reduction on 3-dimensional Cu

Electrochemical CO_(2) reduction reaction(CO_(2) RR)exhibits remarkable potential in producing valuable chemicals with renewable energy.Operating CO_(2) RR in acidic media is beneficial to solve the issue of low carbon utilization brought by(bi)carbonate formation at the cathode.Suppressing the competing hydrogen evolution reaction and achieving stable CO_(2) RR performance remains challenging.Herein,we constructed a 3-dimensional Cu(3D-Cu)gas diffusion electrode(GDE)to achieve efficient C_(2)H_(4) production with a partial current density(j C_(2)H_(4))of over 470 mA cm^(2) and a Faradaic efficiency(FE C_(2)H_(4)) of 40%.With pause electrolysis,the decay rate of the j C_(2)H_(4) is only half that of the traditional constant electrolysis.The GDE after constant electrolysis was found to suffer from severe salt formation,leading to the decreased activity and poor stability.

How to select heterogeneous CO_(2)reduction electrocatalyst

As an important part of carbon neutralization,carbon dioxide electroreduction reaction(CO_(2)RR)can convert CO_(2)into high value-added chemicals and fuels to realize the recycling of carbon resources and solve the problem of environmental pollution.Therefore,exploring the element species and surface structure of the catalyst plays a central role in improving the performance of the catalyst,enhancing the CO_(2)conversion efficiency and forming C1 and C_(2+)products.Here,we summarize the recent progress in the selective regulation of CO_(2)RR reaction products by different elements.In particular,we emphasize the structure-property relationship of CO_(2)RR by the microenvironment of metal center and substrate,heteroatom doping,hydrogen bond network of metal-free polymer,and construction of heterogeneous catalytic system.At the same time,the recent advances for the identification of CO_(2)RR active sites and mechanistic studies on the process of reducing CO_(2)conversion to different products are reviewed,as well as a comprehensive review to the final products.Finally,we outline the inevitable challenges faced by CO_(2)RR and present our own recommendations aimed at contributing to CO_(2)resource utilization.

原位重构限制在三维纳米孔铜内的铋纳米颗粒促电还原CO_(2)

由于单金属Bi在CO_(2)还原反应(CO_(2)RR)中效率较低,通过表面工程复合材料提高电导率和产率是一种有吸引力的方法.在此,我们重构了在三维纳米孔铜结构中的原位生长金属Bi纳米颗粒.得益于三维纳米多孔导电网络和Cu与Bi之间的强相互作用,Bi@np-Cu费米能级向上移动,表现出优异的电催化二氧化碳还原性能.Bi@np-Cu在-0.97 V的电位下具有97.7%的甲酸法拉第效率,电流密度为82 mA cm^(-2).重要的是,该催化剂在连续催化反应40 h后仍能实现超过90%的法拉第效率.DFT计算表明,np-Cu有效地调节了Bi的电子态,优化了中间吸附能,从而提高了Bi的本征活性.这项工作为纳米多孔金属在催化中的应用提供了一个新视角.