Achieving electroreduction of CO2 to CH3OH with high selectivity using a pyrite–nickel sulfide nanocomposite

Abstract

Electrochemical reduction of carbon dioxide (CO₂) to methanol (CH₃OH) catalyzed by transition metals has been proved feasible and effective in aqueous electrolytes. In this work, we introduce a FeS₂/NiS nanocomposite electrocatalyst synthesized by traditional hydrothermal method, which selectively reduces CO₂ to CH₃OH with an unprecedented overpotential of 280 mV and a high faradaic efficiency up to 64% at the potential of −0.6 V vs. reversible hydrogen electrode (RHE). The FeS₂/NiS nanocomposite electrocatalyst exhibits a stable current density of 3.1 mA cm⁻² over a 4 hour stability test. The high selectivity towards CO₂ electroreduction to CH₃OH may be attributed to the special ladder structure of the FeS₂/NiS nanocomposite. The active sites are located at the interface between FeS₂ and NiS which can effectively suppress the side reaction hydrogen evolution reaction and facilitate the CO₂ reduction reaction.