Interfacial design of SnFeNiO/GGAC/γ-AlO/CeO/α-MoO S-scheme heterojunction for PMS-activated photo-Fenton-like removal of phenol and hydrogen production.

The development of efficient and sustainable catalytic systems for wastewater treatment and clean energy production remains a critical challenge in environmental and energy research. In this work, we report the DES-mediated synthesis of a guar gum/activated carbon-derived SnFeNi/Al/Ce/Mo oxide S-scheme heterojunction. Several advanced characterization techniques, including XRD, SEM, XPS, and FTIR, were employed to evaluate the material's crystallinity, morphology, and elemental composition, while EIS analysis confirmed its superior charge transfer efficiency and interfacial kinetics. The synthesized heterojunction exhibited excellent photo-Fenton-like degradation of phenol, achieving 98.31 % removal within 90 min-approximately 5-213 times higher than that of the pristine materials-with a pseudo-first-order rate constant of 0.0852 min. Optimization via the RSM-CCD model identified ideal parameters as pH = 5.40, catalyst dose = 110 mg/100 mL, PMS dosage = 0.97 mM, and temperature = 25 °C. Recyclability tests over seven cycles demonstrated good stability, with 87.49 % phenol removal in the final cycle. Scavenging experiments confirmed that SO• and •OH radicals were the dominant reactive species responsible for phenol degradation. Additionally, the catalytic potential of the synthesized heterojunction was extended to green hydrogen production, with a remarkable yield of 6917.9 μmol g h. This dual functionality highlights the effectiveness of the synthesized heterostructure for integrated environmental remediation and renewable fuel generation, offering a sustainable and cost-effective solution for water purification and hydrogen production.