TiO2 nanotube/ZnIn2S4 nanoflower composite with step-scheme heterojunction for efficient photocatalytic H2O2 production and organic dye degradation

The intellectual design of photocatalysts to advance important photocatalytic goals such as pollutant degradation and hydrogen peroxide production is challenging. In the present work, a novel TiO2 NT/ZIS heterojunction photocatalyst was synthesized by a hydrothermal method and applied for photocatalytic RhB degradation and H2O2 generation. Prepared materials were characterized by different techniques concerning structural, optical, morphological, and electrochemical properties. At the same time, the electronic-structural features and photocatalytic mechanism were profoundly investigated by combining Tauc plots, Mott-Schottky curves, XPS analysis, and scavenging test results. The TiO2 NT/ZIS heterojunction displayed the best activity in H2O2 generation of 9.78 mmol/L after 30 min, which was about 5.1, 2.1, and 1.8 times higher than those of pure P25, TiO2 NT, and ZIS samples, respectively. In addition, the RhB degradation efficiency reached 90.2% on TiO2 NT/ZIS nanocomposite after 120 min, while 18.2%, 37.4%, and 38.6% on pure P25, TiO2 NT, and ZIS, respectively. An S-scheme mechanism was suggested to model and interpret the improved photocatalytic performance of the TiO2 NT/ZIS heterojunction composite. This work provides guidance for the design, development, and application of heterostructure photocatalysts in H2O2 production.