Stable and high-yield hydrogen peroxide electrosynthesis from seawater

Electrocatalytic two-electron oxygen reduction reaction (2e− ORR) in seawater offers a sustainable route for hydrogen peroxide (H2O2) production. However, due to the high concentration of Cl− ions and competitive 4e− ORR, there is a lack of efficient and long-term stable seawater electrocatalysts. Here we report a high-performance electrocatalyst design based on NiPS3 nanosheets enabling efficient H2O2 production from seawater. Specifically, the NiPS3 nanosheets deliver a 2e− ORR selectivity of ∼98%, a H2O2 yield of 6.0 mol gcat−1 h−1 and robust stability for over 1,000 h in simulated seawater. Underlying the exciting performance is the synergy of the S2−, Ni2+ and P4+ sites where the octahedral S2− skeleton repels Cl− ions, the Ni2+ sites enable the modest binding strength of *OOH intermediate, and the P4+ sites interact with H2O to trigger the protonation of proximal O atom of *OOH. The seawater electrocatalysis system also allows for scalable synthesis of solid H2O2, tandem oxidation reaction of biomass to organic acid and direct use of the produced H2O2 as a sterilizing agent. Once integrated with photovoltaics, the solar-powered electrolysis device can operate in real seawater. Our findings pave the way for sustainable conversion of seawater into value-added products. Hydrogen peroxide (H2O2) is a green oxidant with diverse applications. Aided by a nickel phosphorus trisulfide nanosheet electrocatalyst, this work shows a sustainable synthetic route to produce H2O2 from seawater with high yield and impressive stability.