MoS-Based Nanocomposites for Photocatalytic Hydrogen Evolution and Carbon Dioxide Reduction.

Photocatalysis is a facile and sustainable approach for energy conversion and environmental remediation by generating solar fuels from water splitting. Due to their two-dimensional (2D) layered structure and excellent physicochemical properties, molybdenum disulfide (MoS) has been effectively utilized in photocatalytic H evolution reaction (HER) and CO reduction. The photocatalytic efficiency of MoS greatly depends on the active edge sites present in their layered structure. Modifications like reducing the layer numbers, creating defective structures, and adopting different morphologies produce more unsaturated S atoms as active edge sites. Hence, MoS acts as a cocatalyst in nanocomposites/heterojunctions to facilitate the photogenerated electron transfer. This review highlights the role of MoS as a cocatalyst for nanocomposites in H evolution reaction and CO reduction. The H evolution activity has been described comprehensively as binary (with metal oxide, carbonaceous materials, metal sulfides, and metal-organic frameworks) and ternary composites of MoS. Photocatalytic CO reduction is a more complex and challenging process that demands an efficient light-responsive semiconductor catalyst to tackle the thermodynamic and kinetic factors. Photocatalytic reduction of CO using MoS is an emerging topic and would be a cost-effective substitute for noble catalysts. Herein, we also exclusively envisioned the possibility of layered MoS and its composites in this area. This review is expected to furnish an understanding of the diverse roles of MoS in solar fuel generation, thus endorsing an interest in utilizing this unique layered structure to create nanostructures for future energy applications.