Electron flux at the Schottky junction of Bi NPs and MoS۲‑supportedRGO for degradation of Tetracycline

In this work, a heterostructured metallic Bi/MoS۲ photocatalyst (MBix) was prepared viauniform decoration of plasmonic bismuth nanoparticles onto the surface of MoS۲ nanosheets.MBix catalysts were then loaded onto the surface of reduced graphene oxide (RGO) using asimple hydrothermal method to form RGO/MBix nanocomposite. RGO/MBix heterostructuresdemonstrated significantly improved photocatalytic performance for the removal of tetracycline(TC) under visible-light irradiation. The enhanced photocatalytic activity was found to bedependent on the level of Bi and RGO in the catalyst. The degradation rate over the optimumcatalyst (RGO-۲.۵/MBi۱.۰) was six-fold higher than that of pristine MoS۲. The results indicatedthe dual roles of the Bi nanoparticles in the RGO/MBix nanocomposite in improving the lightharvestingability and charge separation attributed to the plasmon-mediated activation of themetallic Bi nanoparticles under visible light, followed by efficient electron migration amongBi/MoS۲ interfaces. The intimate interfacial contact of the metal and semiconductor allows onlythe electron transport from the semiconductor to metallic nanoparticles and hinders electronmovement back across the Schottky barrier, resulting in significantly accelerating the carrierpairs separation and restricting the mobile charges recombination. Therefore, the built-in electricfield at the junction of the Bi nanocrystals and MoS۲ can provide an interesting and efficientpathway for the photocatalytic oxidation of TC. Both of these features in synergy with theinherent characteristics of RGO as a competitive acceptor component, which provided aconduction path for the photo-induced charges, led to remarkable enhancement in thephotocatalytic activity of the nanocomposite. The trapping experiments showed •OH and •O۲−played a crucial role in TC photocatalytic degradation. Additionally, RGO-۲.۵/MBi۱.۰ exhibitedstable activity during the photodegradation of TC over multiple cycles. The present study couldnot only present a novel strategy for increasing the photocatalytic performance of MoS۲ but alsodisplay great potential for the feasibility of utilizing the abundant and low-cost Bi nanoparticlesto replace the precious noble metals to promote the spectral response in the visible region