Efficient uranium reduction of bacterial cellulose-MoS2 heterojunction via the synergistically effect of Schottky junction and S-vacancies engineering

Abstract

Integration of the schottky junction and defect engineering over the adsorbent-semiconductors is a perspective strategy for the photocatalytic reduction of hexavalent uranium (U(VI)), which not only effectively avoid the limited active sites on semiconductors, but also promote photogenerated electrons are transferred to the adsorbent through the schottky junction. Here, we developed a bacterial cellulose-defective molybdenum disulfide (BC-MoS2-x) heterojunction by integrating schottky junction and sulfur vacancy (S-vacancy), targeting at simultaneous selective U(VI) removal. The carbonized BC served as not only a confined framework for the growing of MoS2, but also an ideal electron acceptor and transporter for improving the charge carrier separation efficiency. Specifically, the Schottky Junction and S-vacancy had been proven to effectively synergistically enhance the photoelectrons transfer from MoS2 to carbonized BC. Accordingly, the BC-MoS2-x heterojunction presented high removal efficiency for U(VI) with a removal rate of up to 91% in a wide range of U(VI) concentrations. The BC-MoS2-x heterojunction possessed excellent cycle stability in multiple U(VI) capture test cycles, and exhibited a highly selective U(VI) removal in the system containing an abundant of non-redox-active competing metal cations. Interestingly, organic matter, as an unfavorable factor for U(VI) removal in the traditional radioactive wastewater, had been proven to be used as the hole trapping agent to improve the U(VI) removal efficiency. This strategy may open a paradigm for the development of rationally designed heterojunctions as the photocatalysts for selective U(VI) removal.