Designing g-C3N4/NiFe2O4 S-scheme heterojunctions for efficient photocatalytic degradation of Rhodamine B and tetracycline hydrochloride

Semiconductor based photocatalysis is considered as an effective and sustainable approach for the efficient treatment of effluents containing organic dyes and pharmaceuticals. Herein, visible light responsive g-C₃N₄/ NiFe₂O₄ (CN/NF) composite photocatalysts were designed by sol-gel auto-combustion assisted calcination method using ethylene glycol (EG) as a chelating agent. Bidentate nature and lower molecular weight of EG favour slow hydrolysis of Ni²⁺ and Fe³⁺ ions followed by formation of homogenous gel phase which under auto-combustion produced NF precursors. Calcination of the mixture of dicyandiamide (DCDA) and predetermined amount of NF precursors at 550 °C for 4 h resulted in the formation of CN/NF nanocomposites in which NF nanoparticles are anchored on thick plates of porous CN. The construction of CN/NF S-scheme heterojunctions was established through XPS studies and scavenging tests. The 10CN/NF nanocomposite exhibited superior photocatalytic Rhodamine B (RhB) degradation efficiency (98.6 %) which is 2.7 and 3.1 folds superior than that of pure NF and CN respectively. Additionally, the photocatalytic performance of 10CN/NF for tetracycline hydrochloride (TCH) degradation was found to be 84.32 %. The degradation efficiency was around 1.75 and 2.6 times higher than that was observed for pristine NF and CN correspondingly. The current study will bring fresh insights into the synthesis of CN/NF heterojunctions with an S-scheme charge transfer channel for the efficient treatment of waste waters containing dyes and antibiotics.