Simultaneous photocatalytic treatment of wastewater containing uranium (VI) and tannic acid by ultrathin Bi2WO6/Bi2MoO6 heterojunction

In uranium(VI) (U(VI)) photoreduction, it is still a challenge to simultaneously degrade naturally coexisting organics and explore their impact on U(VI) photoreduction. Meanwhile, how to boost the separation and transport capability of photo-induced carriers is also a hot topic of current research. In this work, an ultrathin Bi2WO6/Bi2MoO6 Z-type heterojunction was developed for the simultaneous treatment of U(VI) and its coexisting organics (tannic acid (TA)). Ultrathin interface engineering increased the contact area and shortened the transmission distance of photo-induced carriers. As a result, ultrathin Bi2WO6/Bi2MoO6 exhibited highly efficient U(VI) removal rate (95.8 %) and TA degradation rate (97.2 %), which were much higher than those of bulk Bi2WO6/Bi2MoO6 and single ultrathin Bi2WO6. In addition, the material possessed excellent stability and recyclability. Importantly, TA not only enhanced U(VI) removal by eliminating holes, but also favored U(VI) removal by serving as a bridge to the catalyst for U(VI) adsorption. Finally, a new mechanism was proposed.