Visible Light-Driven Z-Scheme CNQDs/Ag3PO4 Octopod-Shaped Nanostructures with Exposed {110} Facets for Enhanced Photocatalytic Degradation

Abstract

Although Ag3PO4 possessed high quantum yield (approximately 90%) and strong oxidation potential, its practical application was limited due to serious photocorrosion and inadequate stability. To improve the anti-photocorrsion ability, carbon nitride quantum dots (CNQDs) were loaded on octopod-like Ag3PO4 with {110}-faceted rhombic dodecahedrons. The CNQDs stabilized the high-energy {110} facets via carboxylate-mediated interactions, facilitating oriented assembly into 3D octopod configurations. More importantly, a Z-scheme heterojunction was constructed between CNQDs and Ag3PO4 for electrons transfer from Ag3PO4 to CNQDs, which could not only maintain strong redox potentials but also suppress carrier recombination. The 12.5%CNQDs/Ag3PO4 composite achieved a more than 90% removal of methyl orange within 13 min. Radical trapping and EPR analyses indicated that holes of Ag3PO4 played a dominant role in organics degradation. In addition, •O2−, which was generated from the O2 reduction by photogenerated electrons of CNQDs, also participated in the degradation of organics. This work provides a facet-controlled heterojunction design strategy, leveraging quantum-confined CNQDs to enhance charge kinetics and molecular oxygen activation.