Frustrated Lewis Pairs Boosting Electrochemical Production of Hydrogen Peroxide on Bi-TiO2−x Nanocatalysts

Abstract

Electrocatalytic two-electron oxygen reduction (2e⁻ ORR) offers an environmentally friendly route for H₂O₂ production, yet faces challenges in O₂ activation and *OOH intermediate stabilization. Here, Bi-TiO_2−x nanocatalysts are introduced featuring frustrated Lewis acid-base pairs (FLPs) active sites, where the Bi single atoms with electron-deficient characteristics serve as Lewis acidic (LA) sites and the O atoms surrounding the oxygen vacancy (O_V) act as Lewis basic (LB) sites. The Bi-TiO_2−x catalyst exhibits high H₂O₂ selectivity up to 96.5%. Furthermore, in a flowing electrolytic cell, the H₂O₂ selectivity reaches 93.9% with a yield of 1.56 mol g_catalyst⁻¹ h⁻¹ at −50 mA cm⁻² and is able to maintain a stable reaction for 54 h. Theoretical calculations and in situ spectroscopic analyses indicate that the FLPs structure can effectively promote the dissociation of H₂O and the activation of O₂ during the reaction, provide protons for the subsequent reaction, and facilitate the formation of *OOH intermediates. The coupling system of 2e⁻ ORR with ethylene glycol oxidation significantly improves the selectivity of H₂O₂ to 98.9% and the yield to 3.02 mol g_catalyst⁻¹ h⁻¹, meanwhile, the anode simultaneously produces formic acid as a co-product, which improves the utilization of system resources.