Oxygen doping and hollow structure-mediated effects to enable rapid electron transfer during photocatalytic hydrogen peroxide production

The photocatalytic production of hydrogen peroxide using solar energy is an environment-friendly solution to the energy crisis, but its low efficiency hinders its scale-up feasibility. In this work, a hollow core-shell structure OCN@In 2 S 3 composite photocatalyst was constructed by growing In 2 S 3 ultrathin nanosheets on the surface of O-doped hollow g-C 3 N 4 nanospheres using a two-step hydrothermal method. The hollow structure provided a high specific surface area and enhanced light absorption. O doping increased the number of active sites, and the heterojunction promoted the rapid separation and transfer of photogenerated carriers. Under visible light irradiation, the H 2 O 2 yield of OCN@In 2 S 3 reached 632.5 µmol h −1 g −1 , which was 5.7 times higher than that of g-C 3 N 4 and 12.3 times that of In 2 S 3 , as well as higher than most g-C 3 N 4 -based photocatalysts. Quenching experiments and electron paramagnetic resonance spectroscopy showed that ·O 2 − was an intermediate product formed during photocatalytic H 2 O 2 generation. The reaction primarily followed a two-step single-electron pathway. The Koutecky-Levich diagram confirmed that the synthesized OCN@In 2 S 3 maintained a high two-electron ORR selectivity during the catalytic reaction ( n = 1.67). The photocatalytic mechanism was elucidated by photoluminescence, electrochemical impedance spectroscopy, and ultraviolet photoelectron spectro-scopy, which confirmed that OCN@In 2 S 3 inhibited the recombination of photogenerated carriers. This work provides a simple and attractive strategy for developing highly active energy-conversion photocatalysts.