Efficient charge transfer on the tunable morphology of TiO2/MoS2 photocatalyst for an enhanced hydrogen production

Abstract

The TiO₂/MoS₂ heterostructure consisting of varying concentrations of layered MoS₂ on TiO₂ of different morphology was fabricated successfully by a simple hydrothermal method. In this work, we employed TiO₂ with different morphologies (commercial, nanotube, hierarchical, and nanosheets) for the synthesis of TiO₂/MoS₂ to examine the effect of morphology on hydrogen evolution trend. In particular, the photoinjected electron lifetime was greatly influenced by the structural pattern of the photocatalyst, as photoluminescence spectroscopy study revealed superior electron transfer efficiency in TiO₂ nanosheets of the composite. The structure and optical properties of the as-prepared TiO₂/MoS₂ hybrid materials were confirmed by XRD, SEM, TEM, and PL studies. The hybrid materials indicated the heterostructure formation in the fine-tuned MoS₂–TiO₂ composite. The resultant TiO₂/MoS₂ showed good photocatalytic response than the pristine TiO₂ and MoS₂. Furthermore, at optimized MoS₂ to TiO₂ ratio in the composite, a series of photocatalysts were screened, such as TiO₂ (commercial)/MoS₂, TiO₂ (nanotube)/MoS₂, TiO₂ (hierarchical)/MoS₂ and TiO₂ (nanosheets)/MoS₂ with 2 wt% content of MoS₂, and 29.71, 41.33, 65.54 and 77.41 μmol h⁻¹ g⁻¹ of hydrogen evolution was found, respectively. TiO₂ (nanosheet)/MoS₂ showed the highest rate of hydrogen evolution activity among them, and the introduction of MoS₂ to TiO₂ decreased the rate of charge carrier recombination and increased the hydrogen evolution activity. While promising, these approaches consisting of novelty that includes low cost, simple synthesis process, chemically robust and effective charge transfer pathways have shown to be effective for solar energy conversion to the clean fuel hydrogen production.