Effects of Mg-Zr codoping on the photoelectrochemical properties of a Ta3N5 semiconductor: a theoretical insight

Recent experiments revealed that the Mg-Zr codoped Ta3N5 semiconductor exhibited improved photoelectrochemical activities, but the role of Mg-Zr codoping in the improved photoelectrochemical activity remained unclear. In this study, the density functional theory calculations were preformed to investigate the electronic structures and thermodynamic properties of the Mg-Zr codoped Ta3N5. The results showed that Mg and Zr dopants had nearly the same effects on the electronic structures of Ta3N5, while the thermodynamic properties of Mg and Zr in Ta3N5 were different. The Zr dopant preferentially substituted the Ta atom and compensated for oxygen impurities and nitrogen vacancies, resulting in the cathodic shift of the onset potential of Ta3N5. The Mg dopant preferentially occupied the interstitial site and acted as a delocalized electron donor, contributing to the enhanced photocurrent.