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

Abstract

Electrochemical hydrogen peroxide (H 2 O 2 ) 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 H 2 O 2 production of mesoporous SnO 2 (meso-SnO 2 ) 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 H 2 O 2 production rate than the pristine material. Vacuum annealing led to materials with more surface defects. Meso-SnO 2 annealed under vacuum exhibits distinctive electrochemical properties of two well-separated 2e À O 2 reduction peaks to produce H 2 O 2 as the main product compared to meso-SnO 2 annealed in air. Most importantly, the introduction of surface oxygen vacancies into the meso-SnO 2 crystal structure was determined to be a prominent approach to enhance its ORR performance in producing H 2 O 2 , showing great selectivity of above 85% at an onset potential of $0.6 V RHE . The vacancy-rich meso-SnO 2 reveals enhanced electrocatalytic performance with ORR peak potential to be 0.6 V RHE, 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 SnO 2 -based catalytic materials for H 2 O 2 production.