Binding Site Diversity Promotes CO₂ Electroreduction to Ethanol

Abstract

The electrochemical reduction of CO 2 has seen many record-setting advances in C 2 productivity in recent years. However, the selectivity for ethanol, a globally significant commodity chemical, is still low compared to the selectivity for products such as ethylene. Here we introduce diverse binding sites to a Cu catalyst, an approach that destabilizes the ethylene reaction intermediates and thereby promotes ethanol production. We develop a bimetallic Ag/Cu catalyst that implements the proposed design toward an improved ethanol catalyst. It achieves a record Faradaic efficiency of 41% toward ethanol at 250 mA/cm 2 and −0.67 V vs RHE, leading to a cathodic-side (half-cell) energy efficiency of 24.7%. The new catalysts exhibit an in situ Raman spectrum, in the region associated with CO stretching, that is much broader than that of pure Cu controls, a finding we account for via the diversity of binding configurations. This physical picture, involving multisite binding, accounts for the enhanced ethanol production for bimetallic catalysts, and presents a framework to design multimetallic catalysts to control reaction paths in CO 2 reductions toward desired products.

Heterogeneous Single‐Atom Catalysts for Electrochemical CO2 Reduction Reaction

“…It has a moderate adsorption energy for the important intermediates of CO and COOH, resulting poor selectivity of Cu‐based CO 2 RR catalysts. [ 23,81,182–186 ] The CO 2 RR to CH 4 undergoes an 8e transfer process. For single atoms, especially Fe containing catalysts, trace amount of CH 4 are commonly produced at relative large overpotential accompanied with the major product of CO. [ 47,63,118 ] Strong CO binding strength between metal sites and CO is required to the formation of CH 4 .…”

Renewable electricity storage using electrolysis

“…This is challenging for a single metal catalyst if the intermediates bind to the same site because the M-C bond strengths scale linearly. Multimetallic catalysts take inspiration from the active site of the CO dehydrogenase enzyme CODH, in which cooperative binding to 2 metal atoms stabilizes a CO 2 − transition state (28,29). Cu is a unique CO 2 reduction catalyst because it favors C2+ products, including some like ethanol that are ideal for seasonal storage.…”

“…4B). Alloying Cu with other metals (29,(32)(33)(34) and building nanostructures that modulate the chemical environment of the CO binding site (35)(36)(37) are interesting strategies for steering the C2+ product distribution. Given the complexity of this problem, there is a need for better spectroscopic probes and microscopies that can characterize the structure of the electrocatalytic sites.…”

Controllable Synthesis of Leaf‐Like CuO Nanosheets for Selective CO2 Electroreduction to Ethylene

“…Due to the inert chemical activity of CO 2 molecules, highly efficient catalysts are essential for the efficient CO 2 reduction reaction (CO 2 RR) . The mechanism of CO 2 RR are quite complicated and the products are usually diverse, including C 1 (CO, CH 4 , CH 3 OH, HCOOH), C 2 (C 2 H 4 , C 2 H 6 , C 2 H 5 OH, CH 3 COOH) and C 3+ molecules . Until now, the exploration of highly selective catalysts is still a great challenge.…”