Bias-free Solar Co-production of Hydrogen Peroxide and Chlorine from Seawater Using Single-Atom Electrocatalysts

Abstract Electrochemical hydrogen peroxide (H 2 O 2 ) synthesis via two-electron oxygen reduction reaction (2e⁻ ORR) offers a sustainable alternative to the anthraquinone process, yet practical deployment remains limited by insufficient selectivity, low system-level value, and reliance on freshwater electrolytes. Here we report a photovoltaic-driven single-atom electrocatalyst cell (PV-SAEC) that enables bias-free co-production of H 2 O 2 production with chlorine (Cl 2 ) directly from saline feedstocks. A bio-inspired Ni single-atom catalyst, mimicking the second coordination environment of nickel superoxide dismutase, promotes efficient alkaline 2e⁻ ORR, while a Pt single-atom catalyst selectively catalyzes chlorine evolution at the anode. Under one-sun illumination and zero applied bias, the integrated PV-SAEC system simultaneously produces H 2 O 2 and Cl 2 , while desalinating seawater. Techno-economic and life-cycle analyses reveal clear economic and environmental advantages over incumbent anthraquinone and chlor–alkali processes, establishing a scalable platform for multifunctional seawater valorization.