Pulse potential modulation of Cu-based catalysts for stabilizing formaldehyde oxidation with anodic hydrogen production

Abstract

Cu-based electrocatalyst was found to be an efficient catalyst for the formaldehyde oxidation reaction (FOR), capable of generating H₂ at the anode. However, their stability is compromised due to unfavorable structural reconstruction during electrolysis. In this work, a pulsed potential electrolysis (PE) strategy was proposed to enhance the stability of a Cu-based electrocatalyst (Cu_xO@Cu) in FOR. Under constant potential electrolysis (CE), the formic acid (FA) production rate decreased by 77.5 % (22.5 % remained) after the 20 cycles of electrolysis. In contrast, the PE electrolysis mode exhibited excellent stability, and the FA production rate is still 98.9 % of the first cycle. It demonstrated that the PE electrolysis mode induces the continuous oxidation and reduction of the Cu electrocatalyst, leading to reconstruction and then maintenance of the catalyst Cu_xO/Cu with the optimal Cu⁰/Cu^δ+ ratios, and exposure of advantageous Cu(200) crystal surfaces. Additionally, applying PE could modulate the micro-environment of the electrode by accelerating the mass transfer of the OH^– and HCHO. This work provides a new opportunity to achieve a long-term stable electrocatalytic process of Cu electrocatalyst without the complex catalyst modification and design.