rGO-Wrapped Ag/Ag ₃ PO ₄ /Cu ₂ (OH)PO ₄ S-Scheme Heterojunction Catalysts for High Photocatalytic Performance

Abstract

Designing S-scheme heterojunction photocatalysts is a pragmatic approach for achieving powerful redox ability and high-charge transfer efficiency in photocatalytic reactions. In this work, the reduced graphene oxide (rGO)-wrapped Ag/Ag 3 PO 4 /Cu 2 (OH)PO 4 S-scheme heterojunction photocatalysts (designated as AACG) were constructed for the first time by hydrothermal methods, and the different ratios of Ag 3 PO 4 to Cu 2 (OH)PO 4 in the composites were investigated. The results showed that the AACG11 composite with a molar ratio of Ag[Formula: see text]:Cu[Formula: see text] demonstrated the highest photocatalytic degradation efficiency (93.5%), which was 1.11, 3.74 and 6.15 times higher than that of AACG21, AACG12 and AACG13, respectively. The excellent performance originated from the optimized redox potential and effective separation of holes and electrons, which were facilitated by the S-scheme Ag/Ag 3 PO 4 /Cu 2 (OH)PO 4 heterostructure. Additionally, a close interfacial contact layer formed by rGO within the composites further contributed to this improvement. Species capture experiments indicated that ⋅ O[Formula: see text] and ⋅ OH were the predominant reactive species responsible for Methyl Orange (MO) degradation. This work provides new viewpoints into the design of a highly active catalytic system and highlights the insights of charge transfer behavior in regulating the catalytic activity.