Anion-regulation engineering toward Cu/In/MOF bimetallic electrocatalysts for selective electrochemical reduction of CO_(2) to CO/formate

The conversion of carbon dioxide(CO_(2))into high-value added energy fuels and chemicals(CO,formate,C_(2)H_(4),etc.)through electrochemical reduction(eCO_(2)R)is a promising avenue to sustainable development.However,low selectivity,barren activity and poor stability of the electrodes hinder the large-scale application of eCO_(2)R.Herein,we reported a copper-indium-organic-framework(CuIn-MOF)based high-performance catalyst for eCO_(2)R.Elec-trochemical measurement results reveal that CuIn-MOF exhibits high Faradaic efficiency(FE)of CO and formate(300 mV,FE_(CO)=78.6%at-0.86 V vs.RHE,FE_(HCOO^(-))=48.4%at-1.16 V vs.RHE,respectively)in a broad range of current density(20.1–88.4 mA cm^(-2))with long-term stability(6 h)for eCO_(2)R in 0.5 M KHCO_(3)electrolyte solution.Specifically,through anion-regulation engineering,SO_(4)^(2-)anion precursor is more beneficial for the formic acid generation than NO_(3)^(-)anion precursor;while for SO_(4)^(2-)anion precursor,Cu plays a positive regulating role in eCO_(2)R to CO compared to In.Additionally,the high performance in a home-made eCO_(2)R reactor derives benefit from enhanced intrinsic activity and charge re-distribution can be attributed to the formation of In-doped Cu layer.

Crystal facet engineering coexposed CuIn(200)and In(101)in CuIn alloy nanocatalysts enabling selective and stable CO_(2)electroreduction

The electrocatalytic carbon dioxide reduction reaction(eCO_(2)RR)into high-value-added chemicals and fuels is a promising strategy to mitigate global warming.However,it remains a significant stumbling block to the rationally tuning lattice plane of the catalyst with high activity to produce the target product in the eCO_(2)RR process.To attempt to solve this problem,the Culn bimetallic alloy nanocatalyst with specifically exposed lattice planes is modulated and electrodeposited on the nitrogen-doped porous carbon cloth by a simple two-step electrodeposition method,which induces high Faraday efficiency of 80%towards HCOO-(FEHCOO-)with a partial current density of 13.84 mA cm-2at-1.05 V(vs.RHE).Systematic characterizations and theoretical modeling reveal that the specific coexposed Culn(200)and In(101)lattice facets selectively adsorbed the key intermediate of OCHO*,reducing the overpotential of HCOOH and boosting the FEHCOO-in a wide potential window(-0.65--1.25 V).Moreover,a homogeneous distribution of Culn nanoparticles with an average diameter of merely~3.19 nm affords exposure to abundant active sites,meanwhile prohibiting detachment and agglomeration of nanoparticles during eCO_(2)RR for enhanced stability attributing to the self-assembly electrode strategy.This study highlights the synergistic effect between catalytic activity and facet effect,which opens a new route in surface engineering to tune their electrocatalytic performance.

Carbon‐based metal‐free catalysts for electrochemical CO2 reduction: Activity, selectivity, and stability

Zero or negative emissions of carbon dioxide(CO2)is the need of the times,as inexorable rising and alarming levels of CO2 in the atmosphere lead to global warming and severe climate change.The electrochemical CO2 reduction(eCO2R)to value‐added fuels and chemicals by using renewable electricity provides a cleaner and more sustainable route with economic benefits,in which the key is to develop clean and economical electrocatalysts.Carbon‐based catalyst materials possess desirable properties such as high offset potential for H2 evolution and chemical stability at the negative applied potential.Although it is still challenging to achieve highly efficient carbon‐based catalysts,considerable efforts have been devoted to overcoming the low selectivity,activity,and stability.Here,we summarize and discuss the recent progress in carbon‐based metal‐free catalysts including carbon nanotubes,carbon nanofibers,carbon nanoribbons,graphene,carbon nitride,and diamonds with an emphasis on their activity,product selectivity,and stability.In addition,the key challenges and future potential approaches for efficient eCO2R to low carbon‐based fuels are highlighted.For a good understanding of the whole history of the development of eCO2R,the CO2 reduction reactions,principles,and techniques including the role of electrolytes,electrochemical cell design and evaluation,product selectivity,and structural composition are also discussed.The metal/metal oxides decorated with carbon‐based electrocatalysts are also summarized.We aim to provide insights for further development of carbon‐based metal‐free electrocatalysts for CO2 reduction from the perspective of both fundamental understanding and technological applications in the future.

Copper as a single metal atom based photo-,electro-,and photoelectrochemical catalyst decorated on carbon nitride surface for efficient CO_(2) reduction:A review

The processes of photocatalytic CO_(2) reduction(pCO_(2)R)and electrochemical CO_(2) reduction(ECO_(2)R)have attracted considerable interest owing to their high potential to address many environmental and energy-related issues.In this aspect,a single Cu atom decorated on a carbon nitride(CN)surface(Cu-CN)has gained increasing popularity because of its unique advantages,such as excellent atom utilization and ultrahigh catalytic activity.CN-particularly graphitic CN(g-C_(3)N_(4))-is a photo-and electrocatalyst and used as an important support material for single Cu atom-based catalysts.These key functions of Cu-CN-based catalysts can improve the catalytic performance and stability in the pCO_(2)R and ECO_(2)R during the application process.In this review,we focus on Cu as a single metal atom decorated on CN for efficient photoelectrochemical CO_(2) reduction(pECO_(2)R),where ECO_(2)R increases the electrocatalytic active area and promotes electron transfer,while pCO_(2)R enhances the surface redox reaction by efficiently using photogenerated charges and offering integral activity as well as an active interface between Cu and CN.Interactions of single Cu atom-based photo-,electro-,and photoelectrochemical catalysts with g-C_(3)N_(4) are discussed.Moreover,for a deeper understanding of the history of the development of pCO_(2)R and ECO_(2)R,the basics of CO_(2) reduction,including pCO_(2)R and ECO_(2)R over g-C_(3)N_(4),as well as the structural composition,characterization,unique design,and mechanism of a single atom site are reviewed in detail.Finally,some future prospects and key challenges are discussed.