CO Electroreduction to Near-Unity CO Triggered by Built-in Electric Field Over P-N-Heterojunction CuO-Cd(OH) Interface.

Cu-based nanomaterials have attracted great attention as a new generation of CO electroreduction catalysts. However, significant limitations in the selectivity for a single product impede their industrial applications. Herein, the built-in electric field (BIEF) strategy for the design of Cu-based nano-catalysts is reported, achieving near-unity CO synthesis via the electrocatalytic CO reduction (ECR) on the synthesized P-N-heterojunction CuO-Cd(OH) catalyst. This catalyst showcases extraordinary selectivity, attaining almost 100% CO Faraday efficiency (FE), accompanied by exceptional stability. Furthermore, the industrial-scale flow battery with CuO-Cd(OH) as the cathode manifests FE surpassing 99%, a CO partial current density (j) as high as 303.21 mA cm, and a durable cycling life. In situ characterization and density functional theory calculations revealed that the enhanced ECR activity stems from the CuO-Cd(OH) catalyst interface, which accelerates the electron transfer from Cd(OH) to CuO, thus reducing the free energy barrier of CO-to-CO reaction intermediates and boosting the CO selectivity. This research offers insights into the construction of BIEF to fabricate efficient Cu-based catalysts for ECR industrialization.