Mn-doped CdS/Cu2O: An S-scheme heterojunction for photocatalytic hydrogen production

This study aimed to regulate the band structure and enhance the reduction ability of CdS by substituting it with Mn2+. Subsequently, this nano MnCdS solid solution was anchored on the surface of truncated octahedral Cu2O through a simple hydrothermal process, forming an S-scheme heterojunction at the interface between MnCdS and Cu2O. Equilibrating the Fermi level at the MnCdS/Cu2O heterojunction led to spontaneous diffusion of electrons in MnCdS to Cu2O, generating an internal electric field that drove the recombination of electrons in the conduction band (CB) of Cu2O and holes in the valence band (VB) of MnCdS. Consequently, this process preserved the powerful photogenerated electrons in the CB of MnCdS, facilitating robust photocatalytic hydrogen evolution. The MnCdS/Cu2O exhibited a photocatalytic hydrogen evolution rate of 66.3 mmol g−1 h−1, which was 3.4- and 54.3-times higher than that of MnCdS (19.4 mmol g−1 h−1) and Cu2O (1.2 mmol g−1 h−1), respectively. This study elucidates advanced S-scheme heterojunction catalyst architectures for photocatalytic hydrogen production.