Synergy in metal oxide/metal sulfide binary composites for photocatalysis: mechanisms, applications, and emerging trends

The uncontrolled release of synthetic toxins and micropollutants from industry and consumer sources into freshwater bodies poses a serious risk to aquatic environments and human health. Advanced oxidation processes, specifically heterogeneous photocatalysis, have drawn attention to solve these issues and a possible route to improve the quality of the aquatic environment. This has been obtained by investigating unique materials that can function synergistically with one another. The scientific society has explored different photocatalyst types. Nevertheless, heterojunction photocatalysts in general and binary heterojunction photocatalysts in particular have demonstrated remarkable qualities and unique advantages. The combined impacts of metal oxides (MOx) and metal sulfides (MS) have a dominant synergistic effect. Therefore, metal oxide/metal sulfide heterojunctions are emerging as revolutionary photocatalysts in environmental solutions. Binary composites such as ZnO/ZnS, CuO/CuS, ZnO/CuS, and many others are discussed for their synergetic photocatalytic efficiencies in the degradation of a variety of pollutants, including insecticides, dyes, pesticides, antibiotics, and heavy metals. This review explores multifaceted roles of MOx/MS highlighting the potential of these heterojunctions as a promising pathway towards a more sustainable future. Further, a detailed understanding is provided on how heterojunctions have been employed to catalyze environmental remediation by investigating their different electrical interactions and catalytic capabilities. Finally, the manuscript will recommend guidelines for further advancement in this rapidly evolving, multidisciplinary field of current interest.