Efficient hydrogen peroxide synthesis from seawater via Na- and Pb-codoped SnSe under moderate temperature gradient

Hydrogen peroxide (H₂O₂) plays a crucial role in environmental remediation, chemical synthesis, and energy storage. Nevertheless, its industrial production is energy consuming with significant environmental burdens. Here we show a proof-of-concept thermoelectrocatalytic strategy for H₂O₂ production directly from seawater, driven solely by low-grade waste heat. A low-temperature thermoelectric (TE) material, Na- and Pb-codoped SnSe, is designed as a catalyst that enables efficient H₂O₂ generation under a moderate temperature gradient (ΔT). This system achieves an H₂O₂ production rate of 6.1 mmol g^-1 h^-1 from seawater under ΔT = 120 K, which is competitive with the representative photocatalytic systems. Experimental and theoretical analyses reveal that Na/Pb-codoping improves the TE properties, promotes charge carrier migration under ΔT, and promotes the oxygen reduction reaction toward H₂O₂ formation. The naturally formed strong electric layer at the catalyst-seawater interface further promotes both reaction kinetics and thermodynamic driving forces. Our finding provides a sustainable route for H₂O₂ production from seawater using waste heat and demonstrates great potential of TE-catalysis for waste heat utilization.