Double S-scheme AgBr heterojunction co-modified with g-C3N4 and black phosphorus nanosheets greatly improves the photocatalytic activity and stability

Abstract A ternary heterojunction composite photocatalyst g-C3N4/AgBr/black phosphorus was constructed by co-modifying AgBr with g-C3N4 (CN) and black phosphorus nanosheets (BPNs). The photoluminescence (PL), photocurrent intensity and electrochemical impedance spectroscopy (EIS) results proved that, compared with bare AgBr and binary CN/AgBr and AgBr/BPNs, ternary CN/AgBr/BPNs effectively promoted the separation and suppresses the recombination of electron-hole pair. The photocatalytic experiment proved that the CN/AgBr/BPNs photocatalyst exhibited almost 8 times for degradation rate of MO，and well above those of binary CN/AgBr and AgBr/BPNs. According to trapping experiments of the active species, the analysis of the energy band, we proposed the double S-scheme to explain the charge transfer and the boosting of photocatalytic activity in ternary CN/AgBr/BPNs. Impressively, this double S-scheme facilitated the transmittance of electrons at the CB position of AgBr to the VB of CN and BPNs, and greatly overcome the light corrosion and enhance the stability of AgBr. This work designed a novel S-scheme mechanism heterojunction photocatalytic material, which provides a convenient way for efficient wastewater treatment.