MoS2 Quantum Dots@TiO2 Nanotube Arrays: An Extended-Spectrum-Driven Photocatalyst for Solar Hydrogen Evolution.

TiO2 nanotube arrays (TiO2 NTAs) decorated with molybdenum disulfide quantum dots (MoS2 QDs) were synthesized by a facile electrodeposition method and used as a composite photocatalyst. MoS2 QDs/TiO2 NTAs showed enhanced photocatalytic activity compared with pristine TiO2 NTAs for solar light-promoted H2 evolution without adding any sacrificial agents or cocatalysts. The photocatalytic activity was influenced by the amount of MoS2 QDs coated on TiO2 NTAs. The optimal composition showed excellent photocatalytic activity, achieving H2 evolution rates of 31.36, 5.29, and 1.67 μmol cm-2  h-1 corresponding to ultraviolet (UV, λ<420 nm), visible (Vis, λ≥420 nm), and near-infrared (NIR, λ>760) illumination, respectively. The improved photocatalytic activity was attributed to the decreased bandgap and the surface plasmonic properties of MoS2 QDs/TiO2 NTAs, which promoted electron-hole pair separation and the absorption capacity for Vis and NIR light. This study presents a facile approach for fabricating MoS2 QDs/TiO2 NTA heterostructures for efficient photocatalytic H2 evolution, which will facilitate the development of designing new photocatalysts for environment and energy applications.