BiOCl Nanoplates Doped with Fe3+ Ions for the Visible-Light Degradation of Aqueous Pollutants

Two-dimensional (2D) layered ultrathin bismuth oxychloride nanoplate (BiOCl-UTN) photocatalysts are highly active only under ultraviolet light (energy band gap E-g: 3.0-3.1 eV). Herein, unlike using conventional closed-vessel high-temperature synthetic routes, we prepared unprecedented well-crystalline 2D Fe3+ ion-incorporated BiOCl-UTNs [Fe(III)-BiOCl-UTNs] having ultrathin thicknesses of about 4-5 nm and planar sizes of about 30-50 nm in an open vessel at room temperature and then used in photocatalysis under visible light. The present approach is poly(sodium 4-styrenesulfonate) (PSS)-aided, in which the formation of the distinct intermediate composite [PSS-Bi(OCH2CH2OH)-Fe3+] significantly inhibits the habitual spontaneous growth of BiOCl along the (001) plane and results in Fe(III)-BiOCl-UTNs. The synthesis shows robust reproducibility and allows large-scale production (5.2 g) with a well-controlled morphology, size, and thickness. Instead of using a tedious high-speed centrifugation process, the Fe(III)-BiOCl-UTN product is obtained via electrolyte sedimentation which is facile and cost-effective. The successful doping of Fe3+ ions into BiOCl-UTNs, the sustainable layered structure, and the stable lattice arrangement endow Fe(III)-BiOCl-UTNs with a narrower band gap (E-g: 2.55 eV). As-prepared Fe(III)-BiOCl-UTNs exhibit enhanced separation of photoexcited electrons-holes, rapid transfer of excited electrons to the surface, and significant potential to suppress electron-hole recombination. Consequently, under visible light, Fe(III)-BiOCl-UTNs achieved a substantially improved catalytic performance (>99%, five-cycle recyclability) to photoreduce Cr(VI) ions and photodegrade rhodamine B from aqueous solutions. The present performance surpasses pristine BiOCl-UTNs and state-of-the-art photocatalysts. Moreover, we disclosed the morphological optimization, predominant role of e(-) and O-center dot(2) radicals, and typical photocatalytic reaction mechanism. This work offers the first facile and cost-effective alternative to fabricate the iron-doped layered photocatalyst with superior catalytic activity, extendable for other functional materials and diverse practical applications.

Automated summary

By incorporating Fe3+ ions into two-dimensional bismuth oxychloride nanoplates, a photocatalyst with a narrow band gap, enhanced catalytic performance, and stable structure was successfully synthesized, showing significant improvements in the photoreduction of Cr(VI) ions and photodegradation of rhodamine B under visible light.