Electrocatalytic Reduction of CO2 to Long-Chain Hydrocarbons: Investigating the asymmetric C-C Coupling Mechanism on Pd3Au Catalysts.

Abstract

The electrochemical reduction of CO2 to high-energy-density hydrocarbons is pivotal for addressing energy and environmental challenges. Understanding the mechanisms underlying the conversion of CO2 to long-chain hydrocarbons is both crucial and complex. In this study, we employed density functional theory (DFT) calculations to investigate the C-C coupling mechanisms responsible for the formation of C2-C4 products on Pd3Au catalysts. Our findings highlight the sequential formation of C2-C1 bonds via asymmetric C-C coupling as a critical pathway for generating C3 product, which is essential for controlling product selectivity. Detailed analysis of coupling reactions involving CCH2* and CCH3* intermediates with various C1 species indicates that these asymmetric coupling events are energetically favorable and play a decisive role in the selective assembly of carbon atoms into longer hydrocarbon chains. Moreover, we propose a mechanism wherein the asymmetric coupling of C1-C3 intermediate leads to a diverse array of C4 products. This process underscores the importance of CH2 group coupling with C3 intermediates in forming long-chain hydrocarbons. Our work provides valuable insights into optimizing catalyst design for improved selectivity towards higher hydrocarbons in CO2 reduction processes.