Synergistic utilization of magnetic rGO/NiFe2O4-g-C3N4 S-Scheme heterostructure photocatalyst with enhanced charge carrier separation and transfer: A highly stable and robust photocatalyst for efficient solar fuel (hydrogen) generation

Graphitic-C3N4 is the prime photocatalyst for solar energy conversion applications owing to its inexpensive, non-toxic, low gap energy, chemical and thermal stability. Herein, a rGO/NiFe2O4-g-C3N4 (RNC-3) hybrid hetero-structure photocatalyst was fabricated to realize the effective charge carrier transfer and efficient solar fuel (H2) generation. The photocatalytic H2 generation activity was evaluated under solar light irradiation in the presence of triethanolamine (TEOA) as a hole scavenger. The optimized co-catalysts loadings are 15 wt% and 3 wt% for NiFe2O4 and rGO, respectively. The results obtained show that RNC-3 hybrid heterostructure is an efficient and stable photocatalyst towards water-splitting and presented H2 generation activity of 11,817 mu molg-1h-1, approximately-4 and 76 times higher than NiFe2O4-g-C3N4 and g-C3N4 nanosheets, respectively. Notably, the solar-to-hydrogen (STH) conversion efficiency of 2.44% was achieved, prominently surpassing many reported g-C3N4-based materials. This outstanding performance can be related to the substantial band gap reduction from 2.75 to 2.48 eV and significant PL quenching was observed after the incorporation of NiFe2O4 and rGO, which dramatically improved charge carrier separation and transfer, thereby enhancing the photocatalytic perfor-mance. Furthermore, RNC-3 exhibits convenient magnetic recovery, practical reusability, and high activity, making it a potential visible-light responsive photocatalyst for efficient water-splitting applications.