Role of oxygen impurity on the mechanical stability and atomic cohesion of Ta3N5 semiconductor photocatalyst

Oxygen is a natural impurity in the Ta3N5 semiconductor photocatalyst and very difficult to be completely eliminated in different growth conditions. In this study, density functional theory calculations are performed to unravel the cause of natural existence of oxygen impurity in Ta3N5 from the perspectives of mechanical stability and atomic cohesion. The elastic properties calculations show that the oxygen impurity in Ta3N5 is able to remedy the weakened mechanical stability induced by the nitrogen vacancy in Ta3N5. The atomic cohesion calculations show that the oxygen impurity in Ta3N5 enlarges the valence band width of Ta3N5, suggesting that the oxygen impurity is able to strengthen the atomic cohesion of Ta3N5. Based on our calculation results, we propose that the charge-compensation codoping is a promising strategy to improve the water splitting ability of Ta3N5 and simultaneously maintain the mechanical stability and enhanced atomic cohesion of Ta3N5.