Orange peel derived biochar assisted rGO@MoS₂ composite for visible light driven ciprofloxacin degradation and hydrogen evolution

In the context of global sustainability and clean water initiatives, developing multifunctional catalysts for hydrogen production and pharmaceutical pollutant removal is crucial. Herein, a ternary reduced graphene oxide@MoS₂/orange peel-derived biochar (rGO@MoS₂/ODB) nanocomposite was synthesized via a facile hydrothermal method to enhance photocatalytic and electrocatalytic efficiencies through synergistic assembly. The composite exhibited a hierarchical morphology, confirming successful integration of MoS₂, ODB, and rGO. Photoluminescence analysis revealed significantly reduced charge recombination, with oxygen vacancy concentration increasing to 33.86 % from 14.17 % in pristine MoS₂. The rGO@MoS₂/ODB showed superior hydrogen evolution reaction activity, with a Tafel slope of 107 mV/dec and overpotential of 425 mV at 5 mA/cm 2 , indicating efficient charge transfer. In photocatalysis, it achieved 97.4 % ciprofloxacin degradation under visible light in 100 min, outperforming binary and pristine MoS₂. Performance depended on catalyst dosage, pollutant concentration, and irradiation time; optimum conditions were 25 mg catalyst, 20 ppm CIP, and 150 W lamp. Response surface methodology confirmed high statistical correlation (R 2 > 0.98). The catalyst maintained 93.4 % degradation efficiency after 10 cycles, demonstrating excellent reusability. These findings underscore the novelty of this sustainable, multifunctional composite as a robust platform for clean hydrogen production and wastewater treatment. • Novel rGO@MoS₂/ODB from orange peel biochar enables HER and CIP degradation. • Composite showed 97.4 % CIP removal and 107 mV/dec Tafel slope for HER activity. • RSM optimized degradation; catalyst retained >93 % efficiency after 10 cycles.