Cu and Zn promoted Al-fumarate metal organic frameworks for electrocatalytic CO reduction.

Metal organic frameworks (MOFs) are attractive materials to generate multifunctional catalysts for the electrocatalytic reduction of CO to hydrocarbons. Here we report the synthesis of Cu and Zn modified Al-fumarate (Al-fum) MOFs, in which Zn promotes the selective reduction of CO to CO and Cu promotes CO reduction to oxygenates and hydrocarbons in an electrocatalytic cascade. Cu and Zn nanoparticles (NPs) were introduced to the Al-fum MOF by a double solvent method to promote in-pore metal deposition, and the resulting reduced Cu-Zn@Al-fum drop-cast on a hydrophobic gas diffusion electrode for electrochemical study. Cu-Zn@Al-fum is active for CO electroreduction, with the Cu and Zn loading influencing the product yields. The highest faradaic efficiency (FE) of 62% is achieved at -1.0 V RHE for the conversion of CO into CO, HCOOH, CH, CH and CHOH, with a FE of 28% to CH, CH and CHOH at pH 6.8. Al-fum MOF is a chemically robust matrix to disperse Cu and Zn NPs, improving electrocatalyst lifetime during CO reduction by minimizing transition metal aggregation during electrode operation.