Regulation of three-dimensional hydrophobic state of copper dendrite adjusts the distribution of liquid products from electrochemical reduction of CO2

Abstract

Cu is the most common catalyst for CO2 reduction reaction (CO2RR). Here, we propose a strategy for the design of the wetting state of the catalyst under water to obtain a local environment in which reactants and intermediates are enriched to improve the selectivity of the target product. The addition of 3% polytetrafluoroethylene (PTFE) coating can make the catalyst have the stable triphase interface required for CO2RR without destroying the dendrite structure, thus achieving a twofold enhancement of the intrinsic activity of the active site. Dendrites with low-concentration PTFE coating will soon lose hydrophobic ability after applying potential, while high-concentration PTFE coating will cause dendrite collapse and lose the ability to trap gas between dendrites. The Faradaic efficiency (FE) ratio of methanol (CH3OH) to formic acid (HCOOH) of the hydrophobic electrode is threefold higher than untreated electrode at medium potential, and the FE of ethanol (C2H5OH) increased by twofold at higher potential. These are assigned to the rapid enrichment and diffusion of gas on the surface of the hydrophobic electrode. This work has provided a basis for the design of novel 3D hydrophobic catalysts and may lead to a complete understanding of the mechanism of CO2RR.