Carbonate-Ion-Mediated Photogenerated Hole Transfer to Boost Hydrogen Production

ABSTRACT: Sustainable and scalable H2 evolution through water photocatalysis is an attractive path for carbon-neutral energy supply; however, it is severely limited by sluggish charge separation and photocorrosion of semiconductor photocatalysts. Here, we demonstrate that earth-abundant carbonate ions, widely existing in daily-life water, serve as a hole mediator to redirect the photogenerated hole transfer pathway and then promote the hole-transfer kinetics. The accelerated hole transfer could efficiently reduce the recombination of electron???hole pairs for continuous H2 production with improved photostability of catalysts, including layered indium phosphorus sulfide (In4/3P2S6) and cadmium sulfide. A sustainable H2 evolution rate of 5.1 mmol g???1 h???1 within 60 h or more operation is achieved in the presence of CO32??? anions. In situ electron spin resonance (ESR) spectroscopy studies and transient absorption (TA) measurements reveal that the CO32???/CO3?????? redox couple could rapidly shuttle the photogenerated holes from OH??? radicals anchored on the catalyst surface, effectively eliminating the recombination of electron???hole pairs and catalyst oxidation for boosted H2 generation. The carbonate-ion-mediated hole-transfer strategy provides a new paradigm for designing a cost-effective and advanced photosynthetic system in practical applications.