Enhanced photocatalytic degradation of tetracycline by improving electron flux at the Schottky junction between Bi nanoparticles and MoS2-anchored RGO

Abstract

In this work, a heterostructured metallic Bi/MoS2 photocatalyst (MBix) was prepared via uniform decoration of plasmonic bismuth nanoparticles onto the surface of MoS2 nanosheets. MBix catalysts were then loaded onto the surface of reduced graphene oxide (RGO) using a simple hydrothermal method to form RGO/MBix nanocomposite. RGO/MBix heterostructures demonstrated significantly improved photocatalytic performance for the removal of tetracycline (TC) under visible-light irradiation. The enhanced photocatalytic activity was found to be dependent on the level of Bi and RGO in the catalyst. The degradation rate over the optimum catalyst (RGO-2.5/MBi1.0) was six-fold higher than that of pristine MoS2. The enhanced photocatalytic activity was due to the improved light-harvesting and promoted separation efficiency of carrier pairs through the local surface plasmonic resonance (LSPR) effect of Bi nanoparticles and thus effective electron migration in Bi/MoS2 hetero-interface. Moreover, reduced graphene oxide (RGO) as a supreme electron sink provided a conduction path for excited electrons, and further decreased the rate of electron-hole recombination. The reduced charge recombination was well supported by photoluminescence and electrochemical impedance analyses. The radical trapping experiments indicated that the hydroxyl and superoxide radicals were the main active species to initiate TC degradation. Developing earth-abundant Bi-based photocatalysts, as well as the facile and economical approach to fabricating LSPR-enhanced composite will provide new insights into replacing the noble metals materials for environmental remediation.