Structure–activity relationship of Cu-based catalysts for the highly efficient CO2 electrochemical reduction reaction

Abstract

Electrocatalytic carbon dioxide reduction (CO2RR) is a relatively feasible method to reduce the atmospheric concentration of CO2. Although a series of metal-based catalysts have gained interest for CO2RR, understanding the structure–activity relationship for Cu-based catalysts remains a great challenge. Herein, three Cu-based catalysts with different sizes and compositions (Cu@CNTs, Cu4@CNTs, and CuNi3@CNTs) were designed to explore this relationship by density functional theory (DFT). The calculation results show a higher degree of CO2 molecule activation on CuNi3@CNTs compared to that on Cu@CNTs and Cu4@CNTs. The methane (CH4) molecule is produced on both Cu@CNTs and CuNi3@CNTs, while carbon monoxide (CO) is synthesized on Cu4@CNTs. The Cu@CNTs showed higher activity for CH4 production with a low overpotential value of 0.36 V compared to CuNi3@CNTs (0.60 V), with *CHO formation considered the potential-determining step (PDS). The overpotential value was only 0.02 V for *CO formation on the Cu4@CNTs, and *COOH formation was the PDS. The limiting potential difference analysis with the hydrogen evolution reaction (HER) indicated that the Cu@CNTs exhibited the highest selectivity of CH4 among the three catalysts. Therefore, the sizes and compositions of Cu-based catalysts greatly influence CO2RR activity and selectivity. This study provides an innovative insight into the theoretical explanation of the origin of the size and composition effects to inform the design of highly efficient electrocatalysts.

Electrochemical CO2 Reduction on Cu-Based Monatomic Alloys: A DFT Study

“…Modulation of the catalyst’s surface composition by alloying can directly change the intermediates in their absorption state at the active site and determine the final product during the CO 2 RR process. Therefore, alloying is an effective strategy to adjust the electronic structure and improve the activity and selectivity of CO 2 RR …”

“…11 Therefore, there is an urgent need to design cheap, safe, efficient, and highly selective electrocatalysts to improve the slow kinetics and energy conversion efficiency. 12,13 As early as the 1990s, Hori et al 14 demonstrated that different pure metal catalysts could be used as catalysts for accelerated electrocatalytic CO 2 RR, but their large-scale production and practical applications were limited due to the problems of high cost, poor performance, and poor selection. For example, although the metal Cu has been repeatedly shown to catalyze CO 2 to valuable hydrocarbons or alcohols, it has high overpotentials and a large number of byproducts.…”

“…Therefore, alloying is an effective strategy to adjust the electronic structure and improve the activity and selectivity of CO 2 RR. 12 In the crystal, the Cu(111) densely arranged face has the highest atomic density, and any atom on this face has the fewest number of bonds interacting with atoms on neighboring crystal faces, the lowest surface energy, and the highest structural stability. 35,36 In this work, we designed a series of Cu-based SAAs, denoted as TM 1 /Cu(111), by doping isolated 3d TM atoms on the surface of Cu(111), where TM = Fe, Co, Ru, Rh, Os, Ir.…”

“…In addition, the process of CO 2 RR is usually accompanied by competitive hydrogen evolution reaction (HER) . Therefore, there is an urgent need to design cheap, safe, efficient, and highly selective electrocatalysts to improve the slow kinetics and energy conversion efficiency. , …”