Shifting the O2 reduction pathway from H2O to H2O2via in situ reconstruction of Ti2O3 nanoparticles

The direct electrosynthesis of hydrogen peroxide (H2O2) through a two-electron oxygen reduction reaction (2e- ORR) under ambient conditions has emerged as a promising solution for on-site applications, aiming to replace the energy-intensive, waste-generating, and indirect anthraquinone process. Recent advancements have focused on developing catalysts to enhance their activity and efficiency. However, the dynamic evolution and in situ construction behavior of electrocatalysts during operation have often been overlooked. Herein, we investigate the in situ electrochemical reconstruction process of oxygen-deficient TiO2, which forms on the surface of Ti2O3 during the ORR process. The reconstructed catalyst exhibits a complete transition from a 4e- ORR pathway to a 2e- pathway, exhibiting exceptional performance in synthesizing H2O2 with a faradaic efficiency exceeding 90%. Furthermore, by cross-confirmation with density functional calculations, we validate the transition process of the phase and ORR pathway by in situ electrochemical Raman and infrared spectroscopy.