Catalyst design, measurement guidelines, and device integration for H2O2 electrosynthesis from oxygen reduction

Abstract

The electrosynthesis of H2O2 via a two-electron pathway oxygen reduction reaction (2e− ORR) has emerged as a promising way of carbon-free and on-site production of H2O2. Active and selective electrocatalysts for the 2e− ORR are essential for achieving high O2-to-H2O2 conversion efficiency. In this review, we present the recent progress in the development of 2e− ORR electrocatalysts including Pt-group-metal (PGM) and non-PGM atomically dispersed catalysts and metal-free heteroatom-doped carbons. The impact of the active sites and interface structures on the electrocatalytic process is summarized. Benchmarking of the electrocatalytic activities in terms of O2-to-H2O2 mass activity and site-normalized activity is presented to understand the current status of advancement and to provide an insight into possible future research directions. In addition, some guidelines and pitfalls in typical laboratory measurements for assessing 2e− ORR performance are proposed. Finally, recent advances in high-current-density H2O2 electrosynthesis reactors and devices that exploit electrosynthesized H2O2 are introduced.