Enhanced electrochemical hydrogen peroxide production from surface state modified mesoporous tin oxide catalysts

Abstract

Electrochemical hydrogen peroxide (H2O2) production via the two-electron oxygen reduction reaction (ORR) has received much consideration as a substitute to the well-known industrial anthraquinone method. The present challenge in this area is developing appropriate cost-efficient materials with excellent electrocatalytic properties, durability, and product selectivity. This study examined electrocatalytic performance and selectivity toward H2O2 production of mesoporous SnO2 (meso-SnO2) electrodes prepared using a tunable hydrothermal process. After evaluating the effects of different NaCl concentrations and annealing conditions in the hydrothermal method, an electrode was developed with a significantly improved H2O2 production rate than the pristine material. Vacuum annealing led to materials with more surface defects. Meso-SnO2 annealed under vacuum exhibits distinctive electrochemical properties of two well-separated 2e− O2 reduction peaks to produce H2O2 as the main product compared to meso-SnO2 annealed in air. Most importantly, the introduction of surface oxygen vacancies into the meso-SnO2 crystal structure was determined to be a prominent approach to enhance its ORR performance in producing H2O2, showing great selectivity of above 85% at an onset potential of ∼0.6 VRHE. The vacancy-rich meso-SnO2 reveals enhanced electrocatalytic performance with ORR peak potential to be 0.6 VRHE, and the number of electron transfer numbers is 2.5, but greater durability in alkaline solutions. Thus, this work presents an innovative route for designing, synthesizing, and mechanistic examining enhanced SnO2-based catalytic materials for H2O2 production.