Enhanced catalysis for degradation of antibiotic by hydroxyl-functionalized S-doped BiOCl with high capacity of local spatial charge separation

Abstract

Bismuth oxychloride (BiOCl)-based photocatalysts have projected huge potential in terms of alleviating energy crisis and environmental pollution issues due to their unique layered structure and electronic band structures, while their photocatalytic efficiency still be restricted by the wide bandgap and fast charge recombination. Up to now, band engineering via element doping only cannot solve simultaneously these bottleneck problems mentioned above that are constrained by different bandgaps. In this study, a feasible approach coupling the band regulation with hydroxy modification for achieving high-efficient photocatalysis was put forward. Without involving any organic solvents, a one-pot high-pressure reaction was used to prepare an S-doped hydroxylated BiOCl catalyst (BOC-S-OH) in BiCl3/NaOH/H2O system. Intriguingly, the as-synthesized BOC-S-OH nanosheets have displayed the remarkable enhancement with high kinetic constant k-value (0.015 min−1, which is almost better 15-folds than BOC) toward the photocatalytic degradation tetracycline hydrochloride (TC-HCl) than the reference of pristine BiOCl and only S-doping (BOC-S) as well as only -OH retouched BiOCl (BOC-OH). Above significantly enhanced TC-HCl degraded efficiency is resulting from the synergistic effect of the doping levels for harvesting efficient visible-light energy, the internal electric field associated with covalent bonds of Bi-S and surface electronic trap for promoting the fast charge transform and separation. These synergistic modifications also facilitated to production of reactive species by absorbing charged species, especially the hydroxyl radicals, then endowed with stronger redox ability and caused the dissociation of TC-HCl molecule. This work demonstrated the huge potential and promise of coupling band engineering with surface-modification/defect engineering for layered bismuth-based photocatalysts in the application of antibiotic removal, and also delivered novel insights into design highly efficient bismuth-based photocatalysts.