Two-Dimensional Metal Coordination Polymer Derived Indium Nanosheet for Efficient Carbon Dioxide Reduction to Formate

Abstract

Main group indium materials have been known as promising electrocatalysts for two-electron-involved carbon dioxide reduction to produce formate, which is a key energy vector in many industrial reactions. However, the synthesis of two-dimensional (2D) monometallic nonlayered indium remains a great challenge. Here, we present a facile electrochemical reduction strategy to transform 2D indium coordination polymer into elemental indium nanosheets. In a customized flow cell, the reconstructed metallic indium exhibits a high Faradaic efficiency (FE) of 96.3% for formate with a maximum partial current density exceeding 360 mA cm^-2 and negligible degradation after 140 h operation in 1 M KOH solution, outperforming the state-of-the-art indium-based electrocatalysts. Moreover, <i>in</i> and <i>ex situ</i> electrochemical analysis and characterizations demonstrate that the enhanced exposure of active sites and mass/charge transport at the CO₂ gas-catalyst-electrolyte triple-phase interface and the restrained electrolyte flooding are contributing to producing and stabilizing carbon dioxide radical anion intermediates, thus leading to superior catalytic performance.