Synthesis of QDs self-modified Bi₂MoO₆/Bi₄Ti₃O₁₂ photocatalysts via controlling charge unidirectional flow for effective degradation of organic pollutants

Reinforcing separation of charge carriers and increasing electron density played a leading role in improving photocatalytic performance. In this work, incorporating homojunction and heterojunction in quantum dots (QDs) self-modified Bi₂MoO₆/Bi₄Ti₃O₁₂ (BMO(Q)/BTO) composites had been rationally designed, and a newfangled photocatalyst had been acquired which could realize the fine manipulation of charge carriers flow direction. Among multitudinous samples, the 15-BMO(Q)/BTO composite exhibited the optimal photocatalytic properties and pervasive applicability for removing the various pollutants (dye, mercaptan and heavy metal) under visible light. We utilized the three-dimensional excitation-emission matrix fluorescence spectroscopy (3D EEMs) to fully grasp the degradation behaviors of RhB. The encouraging increase in photocatalytic activity was mainly attributed to the unified transfer of electrons generated by BMO QDs and BTO to the conduction band of BMO, which effectively increased charge carrier lifetime and improved the conduction band electron density. Furthermore, the photocatalytic degradation mechanism over 15-BMO(Q)/BTO composite was systematically investigated by the calculation, trapping experimental and ESR. The ·OH undertook the active constituent in the process of degradation pollutants. The result suggested that the construction of homojunction/heterojunction photocatalysts to enhance electrons density was a reliable design idea.