Development and Mechanistic Studies of Ternary Nanocomposites for Hydrogen Production from Water Splitting to Yield Sustainable/Green Energy and Environmental Remediation

Photocatalysts lead vitally to water purifications and decarbonise environment each by wastewater treatment and hydrogen (H-2) production as a renewable energy source from water-photolysis. This work deals with the photocatalytic degradation of ciprofloxacin (CIP) and H-2 production by novel silver-nanoparticle (AgNPs) based ternary-nanocomposites of thiolated reduce-graphene oxide graphitic carbon nitride (AgNPs-S-rGO(2%)@g-C3N4) material. Herein, the optimised balanced ratio of thiolated reduce-graphene oxide in prepared ternary-nanocomposites played matchlessly to enhance activity by increasing the charge carriers' movements via slowing down charge-recombination ratios. Reduced graphene oxide (rGO), >2 wt.% or <2 wt.%, rendered H-2 production by light-shielding effect. As a result, CIP degradation was enhanced to 95.90% by AgNPs-S-rGO(2%)@g-C3N4 under the optimised pH(6) and catalyst dosage(25 mg/L) irradiating beneath visible-light (450 nm, 150 watts) for 70 min. The chemical and morphological analysis of AgNPs-S-rGO(2%)@g-C3N4 surface also supported the possible role of thiolation for this enhancement, assisted by surface plasmon resonance of AgNPs having size < 10 nm. Therefore, AgNPs-S-rGO(2%)@g-C3N4 has 3772.5 mu molg(-1) h(-1) H-2 production, which is 6.43-fold higher than g-C3N4 having cyclic stability of 96% even after four consecutive cycles. The proposed mechanism for AgNPs-S-rGO(2%)@g-C3N4 revealed that the photo-excited electrons in the conduction-band of g-C3N4 react with the adhered water moieties to generate H-2.

Automated summary

Photocatalysts play a crucial role in water treatment and hydrogen production. This study focuses on the photocatalytic degradation of CIP and H-2 production using novel silver-nanoparticle ternary-nanocomposites. The optimized ratio of thiolated reduce-graphene oxide in the nanocomposites enhances activity by increasing charge carriers' movements and reducing charge-recombination ratios. Under optimized conditions, AgNPs-S-rGO(2%)@g-C3N4 shows a CIP degradation rate of 95.90%. The chemical and morphological analysis supports the role of thiolation in this enhancement, assisted by the surface plasmon resonance of AgNPs. The proposed mechanism involves the photo-excited electrons reacting with water moieties to generate H-2.