Binary pyrene-benzene polymer/Znln2S4 S-scheme photocatalyst for enhanced hydrogen evolution and antibiotics degradation

Recently, Step-scheme (S-scheme) photocatalysts possess great prospects because of the unique charge transport route and high efficiency of charge separation in photocatalysis. Herein, binary Znln2S4/pyrene-benzene polymer (ZIS-PyP) S-scheme heterojunction was fabricated by an in-situ method. The resulting ZIS-PyP exhibits an excellent photocatalytic H2 evolution rate of 54 μmol h−1 which is 2.5 and 10.8-fold than pure ZnIn2S4 and PyP, respectively. The trapping agent experiments reveal the main active species are ·O2− and h+ in the TCH degradation reaction. The characteristic experiments and DFT calculations were used to elucidate the photocatalytic mechanism. The average hydrogen adsorption free energy of ZIS-PyP-H is determined to be −1.51 eV, smallest than that of ZIS-H and PyP-H, which indicates the most favorable for hydrogen mass transfer in ZIS-PyP. Driven by band bending, built-in electric field and Coulombic repulsion, a unique electronic transmission along S-scheme route between ZnIn2S4 and PyP was formed. Therefore, the powerful electrons left in the LUMO of PyP and strong holes in VB of ZnIn2S4 attended to reactions, ultimately achieved an optimal hydrogen production and TCH degradation efficiency in ZIS-PyP S-scheme system.