BiOCl ultrathin nanosheets modified with Fe3+ for enhanced visible light driven photocatalytic activity

Fabrication of OVs enriched BiOCl microflowers doped with Fe3+ for effective destruction of two typical contaminants

In this study, a one-step solvothermal method was used to fabricate Fe3+ doped BiOCl microflowers with abundant oxygen vacancies (OVs) in the presence of glacial acetic acid. Various analytical techniques were employed to characterize the structural, morphological, and optical properties of the prepared samples. The presence of OVs was confirmed by low temperature electron paramagnetic resonance (EPR) analysis. The photocatalytic results show that Fe3+ doped BiOCl photocatalysts have higher activity than the bare BiOCl, and 10% Fe3+/BiOCl exhibits the highest photocatalytic performance, the photocatalytic efficiency of this sample is 2.3 and 1.1 times higher than that of the blank BiOCl toward photocatalytic degradation of perfluorooctanoic acid (PFOA) and rhodamine B (RhB), respectively. Furthermore, Fe3+ doped BiOCl demonstrates excellent reusability. Based on the experimental observations, an enhancement mechanism for the photocatalytic activity of Fe3+ doped BiOCl was reasonably elucidated.

Self-Doping Based Facet Junctions and Oxygen Vacancies in Ferroelectric Bi3TixNb2-xO9 Nanosheets for Boosting Photocatalytic Degradation and Antibacterial Activity

Constructing facet junction in semiconductor photocatalysts has been demonstrated as an effective method to promote charge-carrier separation and suppress carrier recombination. Herein, we proposed a novel but facile self-doping strategy to regulate the crystal facet exposure ratio in ferroelectric Bi3TixNb2-xO9 single-crystalline nanosheets, thereby optimizing its facet junction effect. Through tuning the atomic ratio of Ti and Nb, the exposure ratio of {001} and {110} crystal planes in Bi3TixNb2-xO9 nanosheets can be delicately modulated, and more {110} facets were exposed with the increase of the Ti/Nb atomic ratio as evidenced by the X-ray diffraction and scanning electron microscopy results. A facet junction between {110} and {001} crystal planes was verified based on the density functional theory calculation and photodeposition experiment results. Photogenerated electrons tend to accumulate in {110}, while holes gathered in {001} crystal planes. Owing to the optimal facet junction effect, the sample of Ti1.05 shows the most efficient charge-carrier separation and transportation compared to Ti0.95 and Ti1.00 as supported by the photoluminescence, surface photovoltage, photoelectrochemistry, and electron paramagnetic resonance (EPR) results. In addition, the oxygen vacancy arising from the inequivalent substitution of Nb5+ by Ti4+ as proved by X-ray photoelectron spectroscopy and EPR results and the enhanced ferroelectricity supported by P-E loops can also assist charge-carrier separation and migration. Benefiting from these properties, Ti1.05 outperformed Ti0.95 and Ti1.00 in the photodegradation of organic dye and antibiotic molecules. Meanwhile, the excellent antibacterial activity of Ti1.05 under visible light was also demonstrated by the Escherichia coli sterilization experiment. This work not only presents a novel pathway to adjust the facet junction but also provides new deep insights into the crystal facet engineering in ferroelectrics as photocatalysts.