Synergistic effect of CoPi-hole and Cu(ii)-electron cocatalysts for enhanced photocatalytic activity and photoinduced stability of AgPO.

Recently, AgPO has been demonstrated to be a new kind of material with high visible-light photocatalytic performance for the decomposition of various organic species. To further improve the photocatalytic activity of AgPO, hole cocatalyst modification is a promising approach via the rapid transfer of photogenerated holes for effective oxidation reaction. In this work, Co-Pi as a hole cocatalyst was successfully modified on the AgPO surface by an in situ photodeposition method (referred to as CoPi/AgPO). The results showed that the photocatalytic activity of CoPi/AgPO was greatly improved compared with that of AgPO. Especially, CoPi/AgPO (0.3 wt%) reached the highest photocatalytic rate constant (k = 9.2 × 10 min), a value larger than that of AgPO (k = 1.4 × 10 min) by a factor of 6.6. However, it was further found that more accumulated electrons resulted in an obvious deactivation of AgPO due to the rapid transfer of holes by the Co-Pi cocatalyst, resulting in an obviously decreased photocatalytic performance during repeated tests. To enhance the performance stability of CoPi/AgPO, the Cu(ii) electron-cocatalyst was further loaded onto its surface to prepare the CoPi-Cu(ii)/AgPO photocatalyst. The resultant CoPi-Cu(ii)/AgPO not only indicated a much higher photocatalytic activity than CoPi/AgPO, but also maintained the excellent stability, which was ascribed to the synergistic effect of Co-Pi as a hole cocatalyst and Cu(ii) as an electron cocatalyst. This work may provide new insight for the development of highly stable and efficient photocatalysts for the degradation of organic pollutants.