Observation on Microenvironment Changes of Dynamic Catalysts in Acidic CO₂ Reduction

Abstract

Electrochemical CO₂ reduction reaction (CO₂RR) in acid can solve alkalinity issues while highly corrosive and reductive acidic electrolytes usually cause catalyst degradation. Inhibiting catalyst degradation is crucial for the stability of acidic CO₂RR. Here, we reveal the microenvironment changes of dynamic Bi-based catalysts and develop a pulse chronoamperometry (CA) strategy to improve the stability of acidic CO₂RR. <i>In situ</i> fluorescence mappings show that the local pH changes from neutral to acid, and the <i>in situ</i> Raman spectra reveal the dynamic evolution of interfacial water structures in the microenvironment. We propose that the surface charge properties of dynamic catalysts affect the competitive adsorption of K⁺ and protons, thereby causing the differences in local pH and CO₂RR intermediate adsorption. We also develop a pulse CA strategy to reactivate catalysts, and the stability of acidic CO₂RR is improved by 2 orders of magnitude for 100 h operation, which is higher than most reports on the stability of acidic CO₂RR. This work gives insights on how microenvironment changes affecting the stability of acidic CO₂RR, and provides guidance for designing stable catalysts in acidic electrolytes.