Boosting the Photocatalytic Ability of Bandgap Engineered (Na0.5Bi0.5)TiO3–BaTiO3 by N–Ni Codoping

Bandgap engineered ferroelectrics have raised the utmost interest in achieving visible/near-infrared light utilization. The gap states in ferroelectrics can not only realize the absorption of visible/near-infrared light but also keep their excellent piezoelectricity. However, the impurity energy levels provide limited photogenerated carrier, and the doping ions may act as trapping sites, which make it difficult to convert enough sunlight to chemical or electrical energy. In this work, we report a novel strategy to achieve the cooperative interaction of codopants and significantly enhance the photocatalytic activity of the host ferroelectrics. The (N3–, Ni2+)-codoped (Na0.5Bi0.5)TiO3–BaTiO3 composition was taken as the concrete example, which has a lower bandgap of 2.06 eV without gap state. Largely enhanced photocatalytic activity including organic pollutant degradation and photocatalytic oxidative desulfurization were realized, in which the photodegradation efficiency of RhB was increased by 250% and dibenzothiophene could be degraded to lower than 10 ppm within 150 min. Moreover, a long-standing confusion about the appearance/disappearance of bandgap state in transition-metal-doped ferroelectrics has been properly clarified based on theoretical calculation result. Our work could provide a new insight for advancing the bandgap engineering and improving the energy conversion efficiency.