Hydrogenated MoS2 QD-TiO2 heterojunction mediated efficient solar hydrogen production

Abstract

Herein, we report the development of a hydrogenated MoS₂ QD-TiO₂ (HMT) heterojunction as an efficient photocatalytic system via a one-pot hydrothermal reaction followed by hydrogenation. This synthetic strategy facilitates the formation of MoS₂ QDs with an enhanced band gap and a proper heterojunction between them and TiO₂, which accelerates charge transfer process. Hydrogenation leads to oxygen vacancies in TiO₂, enhancing the visible light absorption capacity through narrowing its band gap, and sulfur vacancies in MoS₂, which enhance the active sites for hydrogen adsorption. Due to the band gap reduction of hydrogenated TiO₂ and the band gap enhancement of the MoS₂ QDs, the energy states are rearranged to create a reverse movement of electrons and holes facilitated the charge transfer process which enhance life-time of photo-generated charges. The photocatalyst showed stable, efficient and exceptionally high noble metal free sunlight-induced hydrogen production with a maximum rate of 3.1 mmol g⁻¹ h⁻¹. The developed synthetic strategy also provides flexibility towards the shape of the MoS₂, e.g. QDs/single or few layers, on TiO₂ and offers the opportunity to design novel visible light active photocatalysts for different applications.