Fabrication of oxygen vacancy modified 2D–2D g-C3N4/ZnFe2O4 heterostructures for amplifying photocatalytic methyl orange degradation and hydrogen production

Abstract

2D–2D heterostructured photocatalysts with direct Z-scheme charge dynamics have garnered immense research interest recently owing to their enlarged hetero-interface, which facilitates the separation and migration of photo-induced charge carriers. Although 2D g-C₃N₄ (GCN) and 2D ZnFe₂O₄ (ZFO) based photocatalysts have been extensively investigated, the design and performance of GCN/oxygen vacancy-rich ZFO (GCN/O_v–ZFO) 2D–2D heterojunction photocatalysts with Z-scheme charge transfer dynamics remained unexplored. Herein, we reported that the thermal condensation of dicyandiamide (DCDA) with ZFO nanosheets at 550 °C for 5 hours resulted in the formation of GCN/O_v–ZFO 2D–2D heterojunctions. Triethanolamine (TEA) acted as both a complexing agent and a soft template during the synthesis of ZFO nanosheets. Scavenging experiments, XPS results and band-edge potential calculations revealed the formation of a direct Z-scheme charge transfer dynamics. GCN/O_v–ZFO2 displayed a maximum MO degradation efficiency of 99.54% which is 3.7 and 1.8 times higher than that of pristine ZFO and GCN, respectively. It also demonstrated elevated photocatalytic H₂ production of 735.4 μmol g⁻¹ h⁻¹, surpassing those of pristine ZFO and GCN by factors of 8.5 and 3.6, respectively. The augmented performance of GCN/O_v–ZFO2 might be attributed to maximized charge separation, extended visible light absorption, improved surface properties and strong redox ability resulting from the combined effect of the 2D–2D heterointerface, introduction of O_vs, and the direct Z-scheme heterojunction.