Bismuth-Based Multi-Component Heterostructured Nanocatalysts for Hydrogen Generation

Developing a unique catalytic system with enhanced activity is the topmost priority in the science of H₂ energy to reduce costs in large-scale applications, such as automobiles and domestic sectors. Researchers are striving to design an effective catalytic system capable of significantly accelerating H₂ production efficiency through green pathways, such as photochemical, electrochemical, and photoelectrochemical routes. Bi-based nanocatalysts are relatively cost-effective and environmentally benign materials which possess advanced optoelectronic properties. However, these nanocatalysts suffer back recombination reactions during photochemical and photoelectrochemical operations which impede their catalytic efficiency. However, heterojunction formation allows the separation of electron–hole pairs to avoid recombination via interfacial charge transfer. Thus, synergetic effects between the Bi-based heterostructured nanocatalysts largely improves the course of H₂ generation. Here, we propose the systematic review of Bi-based heterostructured nanocatalysts, highlighting an in-depth discussion of various exceptional heterostructures, such as TiO₂/BiWO₆, BiWO₆/Bi₂S₃, Bi₂WO₆/BiVO₄, Bi₂O₃/Bi₂WO₆, ZnIn₂S₄/BiVO₄, Bi₂O₃/Bi₂MoO₆, etc. The reviewed heterostructures exhibit excellent H₂ evolution efficiency, ascribed to their higher stability, more exposed active sites, controlled morphology, and remarkable band-gap tunability. We adopted a slightly different approach for reviewing Bi-based heterostructures, compiling them according to their applicability in H₂ energy and discussing challenges, prospects, and guidance to develop better and more efficient nanocatalytic systems.