Boosting Electrochemical Conversion of CO₂ to CO in a Membrane Electrode Assembly Using Nickel–Nitrogen/Carbon Supported Nickel–Zinc Carbide Particle Catalyst

The development of efficient catalysts for CO2 electroreduction to value added products is required to enable electrochemical CO2 conversion technologies that will help mitigate emissions and the devastating climate change related impacts. Atomically dispersed nickel–nitrogen–carbon (Ni–N–C) catalysts are a promising alternative to precious metal (Au and Ag) catalysts for converting CO2 to CO. However, in CO2 electrolyzers, the performance of Ni–N–C catalysts is still lower than that of precious metal catalysts, likely due to the low concentration of catalytically active Ni–Nx/C sites that requires high catalyst loadings that lead to CO2 mass transport limitations. Herein, a new catalyst design is developed based on a structure that comprises Ni–Nx/C active sites along with highly dense nickel zinc carbide (Ni3ZnC) particles─that selectively convert CO2 into CO. In a membrane electrode assembly (MEA) based CO2 electrolyzer, the developed catalyst demonstrated a current density of 448 mA/cm2 and a CO2 to CO Faradaic efficiency of >95% at 3.1 V. This promising MEA performance opens up the opportunity towards the employment of non-precious cathode materials in CO2 electrolyzers as a competitive alternative to precious metals.