A Study of Several Mixed Transition Metal Oxides as Candidate Catalysts for Electrochemical Carbon Dioxide Reduction

Abstract

Rising atmospheric carbon dioxide levels have led to increasingly severe environmental and economic consequences. To mitigate these effects, there is an urgent need to develop technologies that utilize waste and atmospheric carbon dioxide in order to stabilize its atmospheric concentration and prevent further emissions. Thus far, the Bocrasly group has developed, optimized, and characterized a chromium–gallium oxide (CrGaOx) catalyst capable of producing 1-butanol via the electrochemical CO2 reduction reaction. This study builds on that foundation by synthesizing and investigating three additional mixed transition metal oxide catalysts: chromium–aluminum, manganese–aluminum, and manganese–gallium. Each combination tested was found to form metal oxides. In addition, metal composition was found to play a significant role in determining catalyst structure and morphology. Chromium was identified as the source of the characteristic “puff” of the CrGaOx catalyst. Manganese-based systems were shown to form large chunks composed of MnO and an intermetallic oxide. Importantly, both Mn-Al and Mn-Ga catalysts were found to be electrochemically active, producing formate at low Faradaic efficiencies. These findings advance our understanding of pore formation and catalyst morphology, features believed to be critical for the effectiveness of CrGaOx. This work contributes to the broader effort to design and develop more efficient electrocatalysts for CO2 reduction, which in turn will help to close the carbon loop.