Cu2O/CuInS2/TiO2 double S-scheme heterojunctions for enhanced photocatalytic hydrogen evolution

To address the issues of narrow light absorption range and a high carrier recombination rate of TiO2 in photocatalytic hydrogen evolution, a Cu2O/CuInS2/TiO2 catalyst with double step-scheme (S-scheme) heterojunctions was designed and constructed. The construction of the double S-scheme heterojunctions can promote efficient carrier separation under the action of double electric fields while retaining electrons with strong reducing ability, and it can also enhance the light absorption capability through the synergistic effect of different semiconductors. Furthermore, thanks to the synergistic effects among matched energy band positions, sufficient heterojunction interface coupling, and microstructure, Cu2O/CuInS2/TiO2 exhibits an enhanced photocatalytic hydrogen evolution rate (1610 μmol g-1 h-1), which is 3.8 times higher than that of pristine TiO2. This study provides new insights into the design of double heterojunction photocatalysts and the performance enhancement of wide-bandgap photocatalysts.