Enhanced Electroreduction of Carbon Dioxide to Methanol Using Zinc Dendrites Pulse-Deposited on Silver Foam.

Abstract

The electrocatalytic CO2 reduction reaction (CO2 RR) can dynamise the carbon cycle by lowering anthropogenic CO2 emissions and sustainably producing valuable fuels and chemical feedstocks. Methanol is arguably the most desirable C1 product of CO2 RR, although it typically forms in negligible amounts. In our search for efficient methanol-producing CO2 RR catalysts, we have engineered Ag-Zn catalysts by pulse-depositing Zn dendrites onto Ag foams (PD-Zn/Ag foam). By themselves, Zn and Ag cannot effectively reduce CO2 to CH3 OH, while their alloys produce CH3 OH with Faradaic efficiencies of approximately 1 %. Interestingly, with nanostructuring PD-Zn/Ag foam reduces CO2 to CH3 OH with Faradaic efficiency and current density values reaching as high as 10.5 % and -2.7 mA cm-2 , respectively. Control experiments and DFT calculations pinpoint strained undercoordinated Zn atoms as the active sites for CO2 RR to CH3 OH in a reaction pathway mediated by adsorbed CO and formaldehyde. Surprisingly, the stability of the *CHO intermediate does not influence the activity.