Insights into the performance of binary heterojunction photocatalysts for degradation of refractory pollutants.

The uncontrolled discharge of industry- and consumer-derived micropollutants and synthetic contaminants into freshwater bodies represents a severe threat to human health and aquatic ecosystem. Inexpensive and highly efficient wastewater treatment methods are, therefore, urgently required to eliminate such non-biodegradable, recalcitrant, and toxic organic pollutants. In this context, advanced oxidation processes, particularly heterogenous photocatalysis, have received enormous attention over the past few decades. Among the different classes of photocatalysts explored by the scientific community, heterojunction photocatalysts, in general, and binary heterojunction photocatalysts, in particular, have shown tremendous promise, attributed to their many distinct advantages. As such, the present review highlights the application of diverse array of binary heterojunction photocatalysts for eliminating water-borne contaminants. Specifically, a bibliometric analysis has been conducted to identify the ongoing research trend and future prospects of heterojunction photocatalysts. It appears that metal oxide/metal oxide-based heterojunctions have superior thermal and mechanical stability compared to other heterojunction photocatalysts. In contrast, metal oxide/non-metal semiconductor-based heterojunctions are extremely effective in pollutant degradation without significant leaching of metal ions. The review concludes by proposing novel strategic research guidelines in order to make further advances in this rapidly evolving cross-disciplinary field of topical interest.