The two-electron water oxidation reaction (2e-WOR) is a promising route for distributed electrochemical synthesis of hydrogen peroxide (H2O2), an effective and green oxidizer, bleaching agent, and antiseptic. To date, the best electrocatalyst for 2e-WOR, in terms of selectivity against the competing 4e-WOR to form O2, is BiVO4. Nevertheless, BiVO4 is unstable and has a high overpotential of ∼340 mV at 0.2 mA/cm2 for 2e-WOR. Herein, we use density functional theory to identify a new, efficient, selective, and stable electrocatalyst for 2e-WOR, i.e., the ternary oxide calcium stannate (CaSnO3). Our experiments show that CaSnO3 achieves an overpotential of 230 mV at 0.2 mA/cm2, peak Faraday efficiency of 76% for 2e-WOR at 3.2 V vs the reversible hydrogen electrode (RHE), and stable performance for over 12 h, outperforming BiVO4 in all aspects. This work demonstrates the promise of CaSnO3 as a selective and cost-effective electrocatalyst candidate for H2O2 production from water oxidation.
Acknowlegment: X.Z. would like to thank the Stanford Woods Institute for the Environment and the Stanford Natural Gas Initiative for their generous support. This research was supported by the Basic Research Lab Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2017R1A2B3010927, 2018M3C1B7021994, and 2016M3D1A1027664).