Nanophase-Separated Copper–Zirconia Composites for Bifunctional Electrochemical CO(2) Conversion to Formic Acid

[Image: see text] A copper–zirconia composite having an evenly distributed lamellar texture, Cu#ZrO(2), was synthesized by promoting nanophase separation of the Cu(51)Zr(14) alloy precursor in a mixture of carbon monoxide (CO) and oxygen (O(2)). High-resolution electron microscopy revealed that the material consists of interchangeable Cu and t-ZrO(2) phases with an average thickness of 5 nm. Cu#ZrO(2) exhibited enhanced selectivity toward the generation of formic acid (HCOOH) by electrochemical reduction of carbon dioxide (CO(2)) in aqueous media at a Faradaic efficiency of 83.5% at −0.9 V versus the reversible hydrogen electrode. In situ Raman spectroscopy has revealed that a bifunctional interplay between the Zr(4+) sites and the Cu boundary leads to amended reaction selectivity along with a large number of catalytic sites.