Construction of CoTiO3/CdS catalysts in-situ grown on recyclable chitosan hydrogel beads and their application in photocatalytic hydrogen evolution from water splitting

In the photocatalytic water-splitting hydrogen evolution reaction, synthesizing an electron-rich photocatalyst and achieving effective solid-liquid separation are of paramount importance. In this study, CoTiO 3 nanoparticles (CTO) were synthesized using a combination of hydrothermal and calcination methods. Hexagonal CdS (CS) was prepared via the urea-thermal method, and CTO/CS composites were successfully fabricated in a single step through a physical stirring technique. Following the preparation of chitosan hydrogel beads (CHB), they were modified by incorporating ε-polylysine to form CHBL catalysts with a particle diameter of 2 mm. In situ growth of CTO/CS composite materials was conducted while preparing CHBL and performing photocatalytic hydrogen evolution experiments with the newly prepared composite catalyst. The results indicate that the novel composite photocatalyst CTO/CS-15@CHBL has strong hydrogen evolution performance. Under a 10 W LED, the hydrogen evolution rate is 26.2 mmol‧g −1 ‧h −1 , and at a wavelength of 450 nm, the AQY was measured at 1.17 %. Meanwhile, after seven cycles of use (a total of 35 h), there was no significant decline in hydrogen evolution activity, demonstrating that CTO/CS-15@CHBL has good stability for hydrogen evolution. Based on DFT, XPS and KPFM characterization, it is proposed that a Z-scheme heterojunction is established between CTO and CS. The synthesis of CTO/CS-15@CHBL can effectively enhance reaction performance, helping to address issues such as difficulties in solid-liquid separation after the reaction. This research offers new insights into enhancing photocatalytic hydrogen evolution activity and improving catalyst recovery.