Effective solar driven H2 production by Mn0.5Cd0.5Se/g-C3N4 S-scheme heterojunction photocatalysts

Abstract 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 Mn0.5Cd0.5Se/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 Mn0.5Cd0.5Se, 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 Mn0.5Cd0.5Se 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.