One stone, two birds: Multifunctional hierarchical iron sulfide nanosheet arrays enabling self-powered solar thermoelectric water electrolysis

Solar water splitting is essential for future sustainable hydrogen production using renewable resources , but it remains challenging due to expensive solar generators and inefficient electrocatalysts . Herein, we propose a solar thermoelectric water electrolysis system using multifunctional iron foam-supported iron sulfide nanosheet arrays (FeS/IF) as the photothermal conversion unit in solar thermoelectric generator (STEG) and electroactive electrode in water electrolysis. The photothermal FeS/IF rapidly converts solar light to localized heat, supplying the desirable temperature difference for thermoelectric power generation . Meanwhile, the FeS/IF acts as a bifunctional electrode to effectively catalyze the hydrogen and oxygen evolution reactions in alkaline media . As a prototype integrated system , four series-connected FeS/IF-STEG are applied to self-power water splitting with the production rate of 10.7 and 5.3 μmol h −1 for hydrogen and oxygen, respectively. The present study offers new opportunities for rational design of integrated energy systems from renewable solar to sustainable hydrogen.