High‐rate CO₂‐to‐CH₄ Electrosynthesis by Undercoordinated Cu Sites in Alkaline‐Earth‐Metal Perovskites with Strong Basicity

Abstract

The electrochemical CO2 reduction to CH4 has been extensively demonstrated, but still suffers from relatively poor activity and requires high overpotentials especially at large electrolysis rates. Perovskite oxides (AxByO) are one type of promising electrocatalyst for the CO2 reduction due to their tunable electronic structures. In this work, a Ca2CuO3 perovskite oxide catalyst is developed with alkaline‐earth A‐sites, featuring an inherently strong basic strengthand outstanding capability for CO2 adsorption, as well as the undercoordinated Cu sites generated through partial surface Ca2+ cation leaching. The Ca2CuO3 catalyst exhibitsa high partial current density of 517 ± 23 mA cm−2 for producing CH4 at a low applied potential of −0.30 V versus reversible hydrogen electrode, which further reached to a peak value of 1452 ± 156 mA cm−2. Density functional calculations show that the undercoordinated Cu sites allowed to promote the hydrogenation of *CO and subsequent *CHO intermediates, thus leading to the high CH4 activity. This work suggests an attractive design strategy for tuning the A‐sites in perovskite oxides to realize high‐rate CO2‐to‐CH4 electrosynthesis with low overpotentials.

Recent Progress on Perovskite-Based Electrocatalysts for Efficient CO2 Reduction

“…and rare earth metals (Mg, Ca, Ba, etc.). A recent report [88] chose the alkaline-earth element of Ca as an A-site element to synthesize the perovskite oxides (Ca 2 CuO 3 ). The calcium at the A-site caused Ca 2 CuO 3 to feature a strong basic strength and a remarkable capability for CO 2 chemisorption, compared with the non-basic Sr 2 CuO 3 and La 2 CuO 4 .…”

High-Entropy Perovskite Oxides as a Family of Electrocatalysts for Efficient and Selective Nitrogen Oxidation

“…As reported, the cation combined with adjacent oxygen vacancy can work as unsaturated site, enabling improved activation/dissociation of small molecules (N 2 , CO 2 , urea, etc. ). − The electronic properties of cation sites as well as the adsorption/desorption behaviors of reaction intermediates on them are interrelated with the oxygen-vacancy concentration in the perovskite oxides. , We thereby posit that constructing high-entropy perovskite oxides (denoted as HEPs), that render random occupation of multiple cations (≥5) with different physical/chemical properties in the skeletons, − might induce higher oxygen-vacancy concentration and promote the activation/dissociation of N 2 for improved NOR catalysis, which is not yet to be explored to our knowledge.…”

Metal Ce-Leaching Induced Structural Optimization of Bismuth Electrocatalyst for Enhanced CO2 Electroreduction

“…35 In addition, Zheng's group demonstrated the formation of undercoordinated Cu sites on Ca 2 CuO 3 perovskite oxide catalyst by inducing partial leaching of surface Ca 2+ cations, leading to the high activity for the CO 2 electroreduction to CH 4 . 36 Therefore, using the dissolution of appropriate metals to design unique electrocatalysts for the CO 2 RR should be reasonably anticipated, which presents an important aspect for the study of mechanism research. Cerium (Ce) doping has proven to be an effective way to improve the catalytic activity of CO 2 RR electrocatalysts.…”

“…Recently, the Zn leaching and redeposition have been reported by using the Zn-doped Cu 2 O nano-octahedrons as electrocatalysts for CO 2 RR, which results in the superior catalytic performance . In addition, Zheng’s group demonstrated the formation of undercoordinated Cu sites on Ca 2 CuO 3 perovskite oxide catalyst by inducing partial leaching of surface Ca 2+ cations, leading to the high activity for the CO 2 electroreduction to CH 4 . Therefore, using the dissolution of appropriate metals to design unique electrocatalysts for the CO 2 RR should be reasonably anticipated, which presents an important aspect for the study of mechanism research.…”