Fabrication of a direct Z-scheme heterojunction between MoS2 and B/Eu-g-C3N4 for an enhanced photocatalytic performance toward tetracycline degradation

Abstract

A sulfur vacancy (SV)- and nitrogen vacancy (NV)-mediated Z-scheme MoS2/Eu/B-g-C3N4 (MS/BEuCN) photocatalyst was synthesized via thermal polymerization and ultrasonic dispersion methods. Based on the results of various characterizations, a direct Z-scheme heterojunction was successfully constructed between MS and BEuCN, which efficiently promoted photoinduced carrier charge separation and prevented the occurrence of photocorrosion. Meanwhile, the MS/BEuCN composites displayed an enlarged BET specific surface area, widened the visible-light absorption range and accelerated the photoinduced electron-hole pair separation, which significantly promoted photodegradation toward tetracycline (TC). The existence of NVs and SVs had a synergistic effect, providing more active sites, enhancing the visible-light absorbance capacity and promoting the separation of photoinduced carriers charge. The optimized photocatalytic degradation rate of MS/BEuCN could be improved to 99.0%, nearly 1.6, 2.1 and 1.2 times that of MS, CN and BEuCN, respectively. The significant contribution of ·O2− and ·OH in the MS/BEuCN/Vis system was proven via radical quenching experiments and electron spin response measurements (ESR). This work provided a novel combination mode for the construction of high-efficiency heterostructure photocatalysts, which could be applied in environmental restoration.