Pd–Mo bimetallic catalysts for electrochemical reduction of carbon dioxide to carbon monoxide

Abstract

Electrochemical CO2 reduction is considered a promising solution to mitigate the increasing CO2 emissions in the atmosphere. Despite the promising potential of this process, highly active catalysts are needed to enable its efficient operation. Mixed metal oxide (MMO) materials can promote the formation of a dynamic interface between a metal and its oxidized form under applied potential, resulting in a unique interaction with the reaction intermediates. We synthesized a Pd–Mo MMO with controlled size and composition and examined the effect of these properties on CO2 electroreduction. Electron microscopy images confirmed the homogeneous distribution of the synthesized Pd7Mo1 on a ZIF-8-derived porous carbon support, with sizes of ∼1.3 and 4.5 nm for the samples annealed at 200 and 400 °C, respectively. As shown by density functional theory calculations and X-ray photoelectron spectroscopy, adding 12.5 % Mo altered the electronic structure of Pd, enhancing CO desorption, and reducing the potential needed for CO production by up to ∼0.2 V, corresponding to a ∼40 % higher partial CO current density compared to pure Pd. This work demonstrates a facile MMO synthesis enabling particle size and composition control, which will facilitate the development of highly active MMO-derived nanoalloy materials for CO2 electroreduction.