Point defect engineering of elemental phosphorus for photocatalytic hydrogen evolution

Red phosphorus (RP) has been demonstrated for photocatalytic hydrogen evolution (PHE) in recent years. Realistically, P vacancy (VP) defects are present in RP. The constructive or detrimental influences of such defects on the photocatalytic activity of RP should be revealed as the understanding shall provide a platform for further improvement. Herein, we for the first time establish a comprehensive understanding of the crucial relationships between the intrinsic VP defects and the charge dynamics together with the photocatalytic performance in RP. Two main findings are achieved: i) VP-induced deep charge trapping effect is revealed to lead to a severe loss of active electrons during the H+ reduction reaction, resulting in the inferior PHE performance of RP. ii) O doping in the VP sites is demonstrated to be an effective strategy for eliminating the detrimental VP defect states, leading to a long-lived free electron lifetime in RP for enhanced PHE performance. The point defect engineering of RP applied in this study paves a promising way in tuning the physicochemical properties of RP and other elemental -based materials for various applications.

Automated summary

Red phosphorus has been demonstrated for photocatalytic hydrogen evolution, but the P vacancy defects in red phosphorus have a significant influence on its photocatalytic performance. This study establishes the crucial relationships between the intrinsic P vacancy defects and the charge dynamics, and reveals the detrimental effect of deep charge trapping induced by P vacancies on the photocatalytic performance of red phosphorus. Oxygen doping in the P vacancy sites is demonstrated to be an effective strategy for eliminating the detrimental defect states and enhancing the photocatalytic performance of red phosphorus. This research provides a promising way to tune the physicochemical properties of red phosphorus and other elemental-based materials for various applications.