Recent Advances in Nanoscale Engineering of Ternary Metal Sulfide-Based Heterostructures for Photocatalytic Water Splitting Applications

Ternary metal sulfides (TMSs) have been widely documented as an important subgroup of semiconducting materials in solar water splitting into hydrogen (H2) fuel. Recently, interest has been rekindled in this specific branch of chalcogenide materials, particularly in the opportune integration of indium-based TMSs with emerging materials such as MXenes, metal–organic frameworks (MOFs), carbon quantum dots (CQDs), carbon nanofibers (CNFs), and metal-like Mo2C for various nanoscale heterojunction formations. In this mini review, recent outstanding advances of TMS-based heterostructures are concisely reviewed. Following an overview of the fundamental rationales of photocatalytic water splitting, a panorama of different indium-based TMSs (ZnIn2S4, CdIn2S4, and CaIn2S4) and their heterostructures (Z-scheme, conventional heterojunction, and Schottky junction) are outlined and discussed in terms of mechanistic insights and water splitting application prospects. On top of that, investigations of other burgeoning TMS-based heterostructures are carried out, followed by recommendations on future prospects of emerging TMS-based materials and the key challenges in practical water splitting. It is believed that this critical mini review is timely to bring new advances of TMS-based heterostructures and acts as a reference toward future endeavors in developing highly efficient and stable photocatalytic systems for H2 generation.