MoS 2 -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 2 ) has been effectively utilized in photocatalytic H 2 evolution reaction (HER) and CO 2 reduction. The photocatalytic efficiency of MoS 2 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 2 acts as a cocatalyst in nanocomposites/heterojunctions to facilitate the photogenerated electron transfer. This review highlights the role of MoS 2 as a cocatalyst for nanocomposites in H 2 evolution reaction and CO 2 reduction. The H 2 evolution activity has been described comprehensively as binary (with metal oxide, carbonaceous materials, metal sulfides, and metal-organic frameworks) and ternary composites of MoS 2 . Photocatalytic CO 2 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 2 using MoS 2 is an emerging topic and would be a cost-effective substitute for noble catalysts. Herein, we also exclusively envisioned the possibility of layered MoS 2 and its composites in this area. This review is expected to furnish an understanding of the diverse roles of MoS 2 in solar fuel generation, thus endorsing an interest in utilizing this unique layered structure to create nanostructures for future energy applications.