Mo–P sites boosting interfacial charge transfer of 2D/3D MoS2/TiO2 heterostructure for efficient photocatalytic hydrogen production and chromium(vi) reduction

Abstract

Molybdenum disulfide (MoS₂) has emerged as an efficient, cost-effective, and stable non-noble metal cocatalyst for accelerating photocatalytic hydrogen production and chromium(VI) reduction reactions. To construct heterostructure and create more active sites, this study introduces non-metal heteroatom phosphorous into MoS₂ (P-MoS₂) through a facile thermal annealing method, depositing on the surface of TiO₂ hierarchical microspheres (P-MoS₂/TiO₂ HM). The photocatalytic hydrogen production activity of P-MoS₂/TiO₂ HM (1550.30 μmol g⁻¹ h⁻¹) surpasses that of TiO₂ HM (356.39 μmol g⁻¹ h⁻¹) and MoS₂/TiO₂ HM (645.96 μmol g⁻¹ h⁻¹) by 4.36 and 2.40 times, respectively. Moreover, the optimal apparent quantum yield in photocatalytic H₂ evolution of P-MoS₂/TiO₂ HM reaches 7.20% at 350 nm. Furthermore, in the photoreduction performance of Cr(VI), P-MoS₂/TiO₂ HM exhibited 16.33 and 3.06 times higher photocatalytic activity than TiO₂ HM and MoS₂/TiO₂ HM, respectively. These enhancements can be ascribed to the formation of a heterojunction and the presence of Mo–P catalytic sites. Electron spin resonance spectra and radical scavenging experiments indicated that in situ generated H* plays a crucial role in the photoreduction reactions. Computational results revealed that the generated Mo–P sites effectively lower the reaction energy barrier for H* formation and accelerate the kinetic process of photocatalytic hydrogen production and Cr(VI) reduction. This study presents a promising surface modulation strategy for transitional-metal dichalcogenide-based photocatalysts in both energy and environmental applications.