Synergistic effect of CoPi-hole and Cu(ii)-electron cocatalysts for enhanced photocatalytic activity and photoinduced stability of Ag3PO4.

Abstract

Recently, Ag3PO4 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 Ag3PO4, 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 Ag3PO4 surface by an in situ photodeposition method (referred to as CoPi/Ag3PO4). The results showed that the photocatalytic activity of CoPi/Ag3PO4 was greatly improved compared with that of Ag3PO4. Especially, CoPi/Ag3PO4 (0.3 wt%) reached the highest photocatalytic rate constant (k = 9.2 × 10-2 min-1), a value larger than that of Ag3PO4 (k = 1.4 × 10-2 min-1) by a factor of 6.6. However, it was further found that more accumulated electrons resulted in an obvious deactivation of Ag3PO4 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/Ag3PO4, the Cu(ii) electron-cocatalyst was further loaded onto its surface to prepare the CoPi-Cu(ii)/Ag3PO4 photocatalyst. The resultant CoPi-Cu(ii)/Ag3PO4 not only indicated a much higher photocatalytic activity than CoPi/Ag3PO4, 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.