Construction of Z-scheme AgCl/BiOCl heterojunction with oxygen vacancies for improved pollutant degradation and bacterial inactivation

A facile Z-scheme AgCl/BiOCl heterojunction photocatalyst with oxygen vacancies was fabricated by a water-bath method. The structural, morphological, optical and electronic properties of as-synthesized samples were systematically characterized. The oxygen vacancies were confirmed by EPR, which could optimize the band-gap of the AgCl/BiOCl heterojunction and improve the photo-induced electron transfer. The optimized AgCl/BiOCl heterojunction showed excellent photocatalytic degradation efficiency (82%) for tetracycline (TC). Simultaneously, E. coli was completely inactivated within 60 min due to the AgCl/BiOCl heterojunction. The elevated catalytic activity of the optimal AgCl/BiOCl heterojunction was ascribed to the synergistic effect of the enhanced light absorption and effective photoinduced charge carrier separation and transfer. Moreover, the degradation efficiency of the AgCl/BiOCl heterojunction towards ofloxacin, norfloxacin and Lanasol Red 5B was 73%, 74% and 96%, respectively. The experimental factors for the degradation efficiency of TC were also studied. Furthermore, active species trapping experiments indicated that superoxide radicals (˙O2-) were the main reactive species, and the Z-scheme charge transfer mechanism helped to improve the photocatalytic activity.

Fabrication of In-S-co-doped two-dimensional BiOCl coupling with surface hydroxylation toward simultaneously efficient charge separation and redox capability for photocatalytic water remediation

Tailoring energy band structure of bismuth oxychloride (BiOCl)-based photocatalysts by virtue of the metal and/or non-metal elements is one of the promising strategy to address environmental issues, especially plays a crucial role in water remediation. However, it still remains a great challenge to balance the light-harvesting and charge carriers separation. Herein, a feasible strategy was proposed for the simultaneous integration of energy-band modulation and surface hydroxylation to alleviate the as-mentioned contradiction and long-standing issues. By using a simple one-pot hydrothermal method, In-S-co-doped BiOCl photocatalyst coupling with surface hydroxylation (denoted as In/BOC-S-OH) was prepared by the simultaneous co-precipitation and ripening process and exhibited a good photocatalytic activity for removing tetracycline (TC) under visible light-irradiation than the counterparts of In-doped BiOCl (In/BOC), S-doped BiOCl (In/BOC-S) or surface -OH modification BiOCl (In/BOC-OH). Such satisfied photocatalytic efficiency benefits from the synergistic effect on the visible light capture, charge migration and separation associated with the introduction of intermediate energy levels and surface defect, respectively. Accompanying with the introduction of In and S hetero-atoms intercalation, both the potentials of valence and conduction bands were adjusted and the reduction of the bandgap could promote the capture of photons. Meanwhile, the powerful polarization effect associated with the non-uniform charge distribution could promote the special separation of carriers. More importantly, the surface defects induced by hydroxylation could act as traps for photogenerated electrons to stimulate the rapid separation of carriers, thereby causing the cleavage of antibiotics on the catalytic surface. This research offers a reliable strategy and promising scheme via effective solar energy conversion and charge carrier separation to advance photocatalytic wastewater remediation.