title: Photocatalytic hydrogen generation enhanced by band gap narrowing and improved charge carrier mobility in AgTaO3 by compensated co-doping.
abstract: The correlation of the electronic band structure with the photocatalytic activity of AgTaO3 has been studied by simulation and experiments. Doping wide band gap oxide semiconductors usually introduces discrete mid-gap states, which extends the light absorption but has limited benefit for photocatalytic activity. Density functional theory (DFT) calculations show that compensated co-doping in AgTaO3 can overcome this problem by increasing the light absorption and simultaneously improving the charge carrier mobility. N/H and N/F co-doping can delocalize the discrete mid-gap states created by sole N doping in AgTaO3, which increases the band curvature and the electron-to-hole effective mass ratio. In particular, N/F co-doping creates a continuum of states that extend the valence band of AgTaO3. N/F co-doping thus improves the light absorption without creating the mid-gap states, maintaining the necessary redox potentials for water splitting and preventing from charge carrier trapping. The experimental results have confirmed that the N/F-codoped AgTaO3 exhibits a red-shift of the absorption edge in comparison with the undoped AgTaO3, leading to remarkable enhancement of photocatalytic activity toward hydrogen generation from water.
authors.affiliation: Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), Department of Physics, Beihang University, Beijing 100191, P. R. China. zjy@buaa.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Junying
authors.initials: J
authors.lastname: Zhang
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Dang
authors.forename: Scott K
authors.initials: SK
authors.lastname: Cushing
authors.forename: Dong
authors.initials: D
authors.lastname: Guo
authors.forename: Nianqiang
authors.initials: N
authors.lastname: Wu
authors.forename: Penggang
authors.initials: P
authors.lastname: Yin