Phosphorus-induced bandgap modulation in graphene oxide for improved photocatalytic ofloxacin degradation and hydrogen evolution

In this study, phosphorus-doped graphene oxide nanosheets (P-GO NSs) were prepared using modified Hummer’s method. The as-prepared sample was evaluated for the degradation of ofloxacin (OFL) and hydrogen (H 2 ) production. The structural, morphological, optical, and electronic properties of the P-GO NSs were characterized using UV-DRS, FTIR, SEM, XPS, HR-TEM and BET analysis. Phosphorus doping significantly improved the physicochemical properties of graphene oxide (GO) as evident by higher surface area of P-GO NSs (423 m² g⁻¹) than that of pristine GO (160 m² g⁻¹). Additionally, phosphorus doping narrowed the bandgap of GO from 3.9 to 3.3 eV. The P-GO NPs exhibited remarkable photocatalytic performance towards OFL degradation. The % degradation of OFL was observed to be 99.2% for P-GO and 65.0% for GO under UV light irradiation. The degradation experiments were performed under the conditions of: [OFL] 0 = 10 mg/L, [P-GO/GO] 0 = 0.5 g/L, pH = 7 and reaction time = 120 min. The GC-MS was used to identify the degradation products (DPs) of OFL and their ecotoxicity was predicated using the ECOSAR software. Furthermore, the P-GO NPs demonstrated efficient photocatalytic H 2 production under UV light irradiation, reaching H 2 production rate of 410 µmol h -1 g -1 in the presence of Pt (0.2 wt%) as a co-catalyst. Overall, phosphorus doping effectively modified the optoelectronic and structural characteristics of GO, improving charge carrier separation and providing more active sites which led to enhanced performance for removal of organic pollutants and sustainable H 2 production. Graphical abstract