Hydrogen evolution based on the electrons/protons stored on amorphous TiO2

Abstract

The hydrogen evolution reaction (HER) using recyclable mediator is being actively pursued as a route for solar energy conversion. Herein, we introduce a catalyst mediator (MoS₂) that enables proton-coupled electron transfer (PCET) process on the recyclable TiO₂ (H⁺–TiO₂/e⁻) to a separate, catalytic hydrogen production step without requiring post-light energy input. This approach supplies a new insight to hydrogen evolution with the recyclable proton–electron pairs, stored at the semiconductor after the light irradiation. It was found that 80% of the electrons stored on TiO₂ could be devoted to the reduction of H⁺ into H₂ on MoS₂ nanosheets in the dark. The electron transfer to MoS₂ occurs at a rate of 455 μmol h⁻¹ g⁻¹ and 947 μmol h⁻¹ g⁻¹ in the dark and excited state, respectively.