Facile Fabrication of Flower-Like BiOI/BiOCOOH p–n Heterojunctions for Highly Efficient Visible-Light-Driven Photocatalytic Removal of Harmful Antibiotics

Abstract

Novel heterojunction photocatalysts with remarkable photocatalytic capabilities and durability for degrading recalcitrant contaminants are extremely desired; however, their development still remains quite challenging. In this study, a series of flower-like BiOI/BiOCOOH p–n heterojunctions were fabricated via a controlled in situ anion-exchange process. During the process, BiOI formation and even deposition on BiOCOOH microspheres with tight interfacial contact were realized. As expected, BiOI/BiOCOOH heterojunctions revealed remarkable enhancements in photocatalytic antibiotic degradation capacities under visible light irradiation compared with pristine BiOI and BiOCOOH. The best-performing BiOI/BiOCOOH heterojunction (i.e., IBOCH-2) showed much improved photocatalytic CIP degradation efficiency of approximately 81- and 3.9-fold greater than those of bare BiOI and BiOCOOH, respectively. The eminent photocatalytic performances were due not only to the enhanced capability in harvesting photon energies in visible light regions, but also the accelerated separation of electrons and holes boosted by the p–n heterojunction. Active species trapping tests demonstrated that superoxide free radicals (•O2−) and photo-generated holes (h+) were major active species for CIP degradation. Recycling experiments verified the good durability of BIBO-2 over four runs. The facile in situ synthesis route and excellent performance endow flower-like BiOI/BiOCOOH heterojunctions with a promising potential for actual environmental remediation.

Type II Heterojunction Formed between {010} or {012} Facets Dominated Bismuth Vanadium Oxide and Carbon Nitride to Enhance the Photocatalytic Degradation of Tetracycline

“…While for {012}BiVO 4 , the kinetic rate constant only achieved 0.0037 min −1 and increased to 0.0051 min −1 for {012}BiVO 4 /0.1g-C 3 N 4 . Furthermore, the cycling experiments showed that after four cycles ( Figure 6 d), the degradation efficiency of {010}BiVO 4 /g-C 3 N 4 exhibited merely a 3% reduction, which represents a relatively stable performance in the field of photocatalysis [ 48 , 49 , 50 ]. The minor decline in degradation efficiency may be ascribed to the attenuation of surface adsorption with recycling.…”

Synergistic photocatalytic effect of BiOBr–BiOI heterojunctions due to appropriate layer stacking

“…14 BiOBr has been synthesized in powder form presenting different micro and nano-morphologies using diverse techniques such as solvothermal, 15 hydrothermal, 16 liquid-phase exfoliation, reverse micro-emulsion, and self-sacrifice template techniques. 17 Similarly, BiOI with an E g of around 1.7 eV has been extensively evaluated for the photodegradation of several pollutants, 18,19 mainly in powder forms like microspheres, nanoplates, nanosheets, and nanoflakes. 20 The main routes for its synthesis are solvothermal, 21 hydrothermal, 22 in situ oxidation, and chemical vapor deposition (CVD).…”