Band gap engineering of NaTaO3 using density functional theory: a charge compensated codoping strategy

Area of Science:

• Materials Science
• Photocatalysis
• Computational Chemistry

Background:

• Sodium tantalate (NaTaO3) is a promising semiconductor photocatalyst.
• Improving NaTaO3's visible light activity is crucial for applications like water splitting.
• Band gap reduction is a key strategy to enhance photocatalytic performance.

Purpose of the Study:

• To investigate the effects of tungsten (W) and nitrogen (N) codoping on the electronic structure and photocatalytic properties of NaTaO3.
• To theoretically assess the feasibility and impact of W and N codoping compared to individual doping.
• To explore codoping strategies for enhancing visible light absorption and water splitting activity.

Main Methods:

• Theoretical study employing hybrid density functional theory calculations.
• Calculation of formation energies to assess doping feasibility.
• Analysis of electronic band structure, density of states, and optical absorption spectra.
• Comparison of charge-compensated and non-compensated codoping strategies.

Main Results:

• W and N codoping enhances the feasibility of nitrogen incorporation into NaTaO3.
• Codoping creates a charge-compensated system, minimizing vacancy defects.
• W doping introduces donor states, N doping introduces acceptor states, and codoping passivates midgap states.
• The band gap of (W, N)-codoped NaTaO3 narrows to 2.67 eV, extending absorption into the visible region.
• Non-compensated codoping was found to be less effective due to detrimental midgap states.

Conclusions:

• W and N codoping is a viable strategy to enhance the visible light photocatalytic activity of NaTaO3.
• The (W, N)-codoped NaTaO3 exhibits a narrowed band gap and maintains water splitting activity.
• This material shows potential as an efficient photocatalyst for visible light-driven water splitting.