Hollow Structured Metal Sulfides for Photocatalytic Hydrogen Generation

Metal sulfides (MSs) are a promising class of materials for photocatalytic hydrogen generation due to their distinct features of photosensitivity, electrical conductance, and photoelectrochemical stability. However, the photocatalytic activity of solid structured MSs is often compromised due to low incident photon absorption, high charge carrier recombination, inadequate catalytic active sites, and slow mass and charge diffusion. The development of hollow structured MSs alleviates these limitations and achieves higher H-2 generation than solid structured counterparts. This minireview aims to review the recent advances in the development of synthetic methods for various hollow structured MSs that are designed to enhance light absorption and fasten mass diffusion. Particularly, this report highlights the advent of sophisticated heterostructured hollow MSs for the application in photocatalysis, in which the formation of heterojunction at the semiconductor interface ensures spatial separation of charge carriers. The synergy between the hollow structure and heterostructure dramatically increases the H-2 generation rate by providing increased light absorption, delayed charge recombination, and accelerated mass diffusion. We also point to potentially fruitful research directions in this field, in hope that this minireview serves as a stepping stone for the future development in hollow MSs for photocatalytic applications and beyond.