Effective solar driven H₂ production by Mn_0.5Cd_0.5Se/g-C₃N₄ S-scheme heterojunction photocatalysts

Photocatalytic technology offers a practical way to solve the energy crisis by producing hydrogen under sunlight but its performance is encumbered by the fast recombination of photoinduced electron-hole pairs. Constructing heterojunctions to form built-in electric fields could separate these electrons and holes, finally enhancing the photocatalytic efficiency. Herein, a Mn_0.5Cd_0.5Se/g-C₃N₄ (MCS/CN) heterojunction was fabricated by a facile method to tap into this advantage. 2%MCS/CN shows a hydrogen evolution rate of up to 354.5 μmol in 3 h, which is 4.49 and 126.6 times that of pure g-C₃N₄ and Mn_0.5Cd_0.5Se, respectively. Its photocatalytic stability is proved by six cycling tests. Photocurrent, EIS, along with PL spectra, prove that the recombination of photoinduced electron-hole pairs is inhibited by constructing a heterojunction between Mn_0.5Cd_0.5Se and g-C₃N₄. In summary, this work demonstrates the enhancement of photocatalysis by constructing a S-scheme heterojunction and offers a feasible way to develop other effective photocatalysts.