Multiple heterojunctions in photocatalysis

Photocatalysis is a viable tool for water splitting, degradation of pollutants & hazardous organic compounds, disinfection of microorganism etc. In any case the efficiency of photocatalysis depends on the light absorption capability, recombination of charge carriers and charge transport to the catalytic surface. Creating heterojunction is the most effective strategy to accomplish the above mentioned characteristics. Over the past few years photocatalyst research is trending around how to associate various heterojunctions appropriately to develop multifunctional high performance photocatalyst. But the process is not so simple. Even the selection of appropriate materials to generate suitable interfaces is ambiguous. The fabrication strategy is complicated. The present review article attempts to furnish generalization regarding the material selection and fabrication of efficient and stable multiple heterojunction photocatalyst, after critical analysis of research data. The article encrypts section wise detailing of ten types of multiple heterojunctions, their charge separation mechanism, principle of fabrication, synthesis methods and diverse photocatalytic application. The challenges associated with type II and Z-scheme photocatalysts as well as the evolution of S-scheme heterojunction is extensively detailed. The developmental steps involved in these heterojunctions are illustrated. Presence of the highly reactive holes and electrons with high oxidation and reduction potentials, and enhanced charge separation through the internally developed electric field makes S-scheme an exceptional heterojunction. The common synthesis methods as well as the methods to evaluate the charge transfer pathway are illustrated. As a channel for future development the troubles associated with multiple heterojunction is addressed in terms of its synthesis, stability and commercialization. To the best of our belief, this is a novel approach can definitely provide a deep insight regarding the multiple aspects of multi junction catalyst and thereby make an impact in photocatalysis research progress.