Oxygen vacancies induced by zirconium doping in bismuth ferrite nanoparticles for enhanced photocatalytic performance

Doping with certain foreign metal ions in a photocatalyst might introduce surface defects (such as extrinsic oxygen vacancies), which can probably play an important role in the photocatalytic performance. In this work, oxygen vacancies were for the first time introduced into bismuth ferrite (BiFeO₃, denoted as BFO) nanoparticles by zirconium (Zr) doping, and the relationship between oxygen vacancies and the photocatalytic activity of Zr-doped BFO was investigated. It was found that the optical properties and the photocatalytic activities of Zr-doped BFO photocatalysts were significantly affected by the Zr doping amount. The Zr-doped BFO photocatalysts showed much higher photocatalytic activities for methyl orange degradation or Cr(VI) reduction than the pristine BFO. When the Zr doping content was 2mol%, the highest photocatalytic efficiency was achieved, which was more than two times that of the pristine BFO. The boosted photocatalytic performance of Zr-doped BFO was mainly attributed to the presence of surface oxygen vacancies induced by Zr doping, which could act as electron traps and active sites to promote the efficient separation and migration of photogenerated charge carriers, as verified by the trapping experiments and the photoelectrochemical measurements. Thus, the present work provides a simple approach to introduce oxygen vacancies in semiconductor photocatalysts through metal ion doping with a great potential for development of efficient visible light photocatalysts, and also enlarges the understanding of surface-defect dependence of photocatalytic performance for environmental remediation.