Sub-2 nm mixed metal oxide for electrochemical reduction of carbon dioxide to carbon monoxide

Mixed metal oxide (MMO) represents a critical class of materials that can allow for obtaining a dynamic interface between its components: reduced metal and its metal oxide counterpart during an electrocat-alytic reaction. Here, a synthetic method utilizing a MOF-derived micro/mesoporous carbon as a template to prepare sub-2 nm MMO catalysts for CO2 electroreduction is reported. Starting from the zeolite imi-dazolate framework (ZIF-8), the pyrolyzed derivatives were used to synthesize sub-2 nm Pd-Ni MMO with different compositions. The Ni-rich (Pd20-Ni80/ZC) catalyst exhibits unexpectedly superior perfor-mance for CO production with an improved Faradaic efficiency (FE) of 95.3% at the current density of 200 mA cm-2 at-0.56 V vs. reversible hydrogen electrode (RHE) compared to other Pd-Ni compositions. X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of Ni2+ and Pd2+ in all composi-tions, demonstrating the presence of MMO. Density functional theory (DFT) calculation reveals that the lower CO binding energy on the surface of the Pd20-Ni80 cluster eases CO desorption, thus increasing its production. This work provides a general synthetic strategy for MMO electrocatalysts and can pave a new way for screening multimetallic catalysts with a dynamic electrochemical interface. & COPY; 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This article reports a synthetic method using MOF-derived carbon as a template to prepare sub-2 nm mixed metal oxide (MMO) catalysts for CO2 electroreduction. The Ni-rich (Pd20-Ni80/ZC) catalyst exhibits superior performance compared to other Pd-Ni compositions, with improved CO production and Faradaic efficiency. This work provides a general synthetic strategy for MMO electrocatalysts and can pave a new way for screening multimetallic catalysts with a dynamic electrochemical interface.