Rational Design of Heterojunction Photocatalyst for Pollutant Degradation (Dyes)-a Review

Development in industrial sectors such as textile, paints, paper, and cosmetics creates a complicated problem in the ecosystem and human health by utilizing binary coloring materials (methylene blue, rhodamine B, etc.). Photocatalysis is one such most widely used technology for environmental remediation, in which a sunlight-based initialing factor was utilized. However, issues related to conventional photocatalysis, like fast recombination of photo-generated electron and hole pairs, limited visible light absorption property, and poor redox abilities of the charge carriers, must be addressed to improve semiconductor photocatalysts properties and catalytic performance. Enormous efforts have been undertaken to overcome these problems. Modeling of semiconductor photocatalysts is beneficial for understanding and optimizing the functional property. Engineering of semiconductor photocatalyst was done by various techniques such as Schottky, Type-I, Type-II, and Type-III heterojunction formation, through which an efficient photocatalyst retarding the demerits (optical property, spatial charge distribution, recombination, etc.) faced by normal (non-heterojunction) semiconductor photocatalyst can be obtained. The basic principle behind heterojunction formation and its utilization was discussed. The synergistic effect between two different materials significantly impacted their photocatalytic activity improvement. In this review, we have exemplified the purpose of heterojunction formation, their types, and the band potential findings necessary for evaluating semiconductors' ability for the redox process. Furthermore, the future perspective for enhanced photocatalytic material design providing a newer pathway for upcoming research works was provided.