In situ mapping the electrocatalytic production of Hydrogen peroxide by reflection absorption imaging

Abstract

Hydrogen peroxide (H₂O₂), as an environmental-friendly and pollution-free oxidant, plays an irreplaceable role in various fields. Electrochemical two-electron oxygen reduction has garnered extensive attention as a safe, green, and sustainable alternative for H₂O₂ production, with its yield being directly related to the performance of the electrode materials. Conventional electrode performance characterization methodologies, however, are limited to overall detection and lack the capability to detect H₂O₂ concentration (c(H₂O₂)) distribution. To overcome this bottleneck, a reflection absorption imaging (RAI) method is proposed herein to map the c(H₂O₂) distribution on the electrode surface, which enables real time and in situ visualization of differences across various locations on the electrode surface. A calibration process is conducted to correlate light intensity data with c(H₂O₂), while the feasibility of this method is verified through RAI and traditional UV–Vis testing on current mainstream membrane electrode platforms, including bare commercial gas diffusion layer (GDL) and GDL-supported gas diffusion electrodes with either hydrophilic or hydrophobic catalyst layers. Furthermore, this methodology was leveraged to in situ monitor and elucidate the H₂O₂ production behavior at the interface of a recently constructed structurally discontinuous carbon film electrode. This approach holds promise in guiding the design of electrode architectures with superior H₂O₂ production performance.