Design And Performance Of Electrocatalytic CO₂ Reduction Catalysts

Electrocatalytic reduction of carbon dioxide（CO₂ER）to reusable fuel is a significant step to balance the carbon cycle and alleviate the energy crisis.Currently,CO₂ can be electrochemically reduced to CO and multicarbon products(C₂₊),higher efficiency and deeper theoretical research are needed yet.How to improve the selectivity of a single product,how to construct an appropriate model catalyst to verify the reaction mechanism and how to thoroughly explore the reaction path of CO₂ER to multicarbon products are all urgent problems to be solved.This paper focuses on the design of CO₂ER reaction catalysts with the goal of improving performance and exploring the reaction mechanism.This paper carried out the following research:Pd-Au alloy model catalysts that improve CO Faraday efficiency（FE）and copper silicate catalysts with Cu⁰-Cu⁺active sites that improve C₂₊FE.This paper describes a seed-mediated growth method to synthesize ultrathin Pd-Au alloy nanoshells with controllable alloying degree on Pd nanocubes.Pd@Pd₃Au₇ nanocrystals show superior CO₂ER performance,with a 94%CO faraday efficiency（FE）at-0.5 V vs reversible hydrogen electrode（vs RHE）and approaching100%CO FE from-0.6 to-0.9 V.The enhancement primarily originates from ensemble and ligand effects,i.e.,appropriately proportional Pd-Au sites and electronic back-donation from Au to Pd.In situ attenuated total reflection surface-enhanced infrared adsorption spectroscopy（ATR-SEIRA）and density functional theory（DFT）calculations clarify the reaction pathway.This paper offers a general strategy for the synthesis of bimetallic nanocrystals to explore the structure-activity relationship in catalytic reactions.On the basis of CO₂ER to CO,the reaction mechanism of CO₂ER to C₂₊was further explored.This paper reports the controllable construction of Cu⁰-Cu⁺sites ascribed from the well-dispersed Cu O loaded copper phyllosilicate lamellar structure via an ammonia evaporation hydrothermal method.20%Cu/Cu Si O₃ shows the superior and stable CO₂ER performance with 51.8%C₂H₄ Faraday efficiency during the 6 hours-test.The enhancement is mainly attributed to the synergistic effect between the Cu⁰ and Cu⁺sites which are originated from Cu O and copper phyllosilicate,i.e.,Cu⁰ is conducive to activate CO₂,transfer electrons and boost C-C coupling;Cu⁺contributes to strengthen intermediate*CO adsorption during CO₂ER.In situ ATR-SEIRA and DFT calculations further assist in explaining the synergism mechanism over Cu⁰-Cu⁺sites.This paper provides an experimental strategy to explore the roles of Cu in different valence states during CO₂ER and improve Cu-based catalysts’performance in CO₂ER.