Suppression of Point Defects for Band Edge Engineering in a Semiconducting Photocatalyst

Currently, photocatalytic and photoelectrochemical reactions show poor utilization of photoenergy, and the underlying mechanism remains unclear. Previous investigations focused on the undesirable band edge energetics rooted in point defects, while targeted solutions for band edge engineering seldom promote the performance of the reactions. In this study, the suppression of point defects for band edge engineering is studied in a model of titanium-doped Ta₃N₅ by means of density functional theory and impurity scattering. On the basis of the calculated impurity scattering mobility, the point defects in Ta₃N₅ will result in neutral impurity scattering, suppressing the kinetics of bulk charge transports. Introduced titanium dopants for band edge engineering are probably compensated by the point defects, leading to ineffective band edge engineering for Ta₃N₅. In addition, compensations between point defects and titanium dopants result in ionized impurity scattering, aggravating the bulk charge transport in Ta₃N₅.