Photocatalytic Activity of NaTaO₃ Doped with N, Mo, and (N,Mo): A Hybrid Density Functional Study

Abstract

A systematic study using density functional theory has been performed for NaTaO3, codoped with Mo and N, with the objective of improving its photocatalytic activity for water splitting under visible light. The utilization of a more reliable hybrid density functional, as prescribed by Heyd, Scuseria, and Ernzerhof, is found to be effective in predicting the band gap of NaTaO3 (4.05 eV) in agreement with the experimental result (4.1 eV). The effect of individual dopant elements, Mo and N, has also been discussed. The monodoped systems show reduced band gap, with the presence of discrete midgap states, which have adverse effect on the photocatalytic property. However, those isolated states are passivated in the case of codoping with both Mo and N, leading to the formation of a continuum band structure ensuring improved charge carrier mobility. The band gap is reduced to 2.33 eV due to codoping of Mo and N, resulting in enhancement of visible light activity by an appreciable extent. The band alignments for the codoped NaTaO3 are well positioned for the feasibility of both photo-oxidation and photoreduction of water. Hence the charge-compensated Mo and N codoped NaTaO3 can be a promising photocatalyst for water splitting due to improved visible light activity as well as lower possibility of electron–hole recombination.