Band structure alignment transitioning strategy for the fabrication of efficient photocatalysts for solar fuel generation and environmental remediation applications

Indium hydroxide (In(OH)3) and indium oxide (In2O3) have proven to be efficient catalysts for photocatalytic water-splitting reactions to produce hydrogen (H2) and for organic pollutant degradation applications. However, the limited optical absorption features of indium-based nanostructures have restricted their practical applications. In this study, we have successfully designed indium hydroxide- and indium oxide-loaded metal sulfide (cadmium sulfide, CdS) heterostructures as excellent photocatalytic systems for photocatalytic hydrogen evolution and tetracycline hydrochloride pollutant degradation reactions. In this system, In(OH)3 and In2O3 established Type-I and S-scheme heterojunctions, respectively, with CdS, resulting in superior charge separation properties and outstanding photocatalytic activity. Specifically, the rational and appropriate design of the aforementioned indium-based heterostructures promoted the separation of photoexcited charge carriers via Type-I and S-scheme paths. Accordingly, enhanced photocatalytic H2 evolution activities of 9.58 and 14.98 mmol·g-1·h-1 were achieved for CdS-In(OH)3 and CdS-In2O3, respectively. Furthermore, the highest degradation efficiency of CdS-In2O3 was ∼ 90%, which was higher than those of CdS-In(OH)3 (72%) and bare CdS nanorods (51%). Therefore, the results of this study provide an opportunity to enhance the catalytic activities of heterostructured photocatalytic systems by utilizing the strategy of transitioning band structure alignment from the Type-I to the S-scheme.