Jieru Luo

Construction of exfoliated g-C3N4 nanosheets–BiOCl hybrids with enhanced photocatalytic performance

Exfoliated g-C3N4 nanosheets (CNs) were composited with bismuth oxychloride (BiOCl) to fabricate a series of hybrids via a facile chemical deposition–precipitation method in this investigation. The as-synthesized BiOCl–CNs hybrids were then fully characterized by a collection of analytical techniques. It was obviously observed that CNs were in intimate contact with hierarchical BiOCl flowerlike units to form heterojunction structures, which facilitates transfer and efficient separation of photoinduced electron–hole pairs, thus greatly increasing catalytic activity upon visible light irradiation. Together with other merits such as enlarged specific surface area, favorable optical properties, and suitable energy-band structures, these robust BiOCl–CNs hybrids showed significantly enhanced photocatalytic performance towards Rhodamine B (RhB) dye removal. Under identical conditions, the apparent photocatalytic reaction rate of the best hybrid BiOCl–CNs-3% was about 2.1 and 26.6 times as high as those of BiOCl and CNs alone, respectively. A possible photocatalytic mechanism was also proposed by means of active species trapping measurements, revealing that superoxide radicals (˙O2−) played a crucial role during the catalytic process.

Poly(vinyl pyrrolidone)-assisted hydrothermal synthesis and enhanced visible-light photocatalytic performance of oxygen-rich bismuth oxychlorides

A series of novel oxygen-rich bismuth oxychloride (Bi12O17Cl2) were synthesized through a facile poly(vinyl pyrrolidone) (PVP)-assisted hydrothermal route. These obtained Bi12O17Cl2 samples were characterized by various physicochemical techniques. It was found that a proper addition amount of PVP could promote the transformation of Bi12O17Cl2 morphology from irregular clusters to three-dimensional hierarchical flower-like microspheres that were nominated as sample BP2. As-synthesized samples were subjected to a photocatalytic degradation of dye Rhodamine B (RhB) or 2,4-dichlorophenol (2,4-DCP) under visible light. Among all candidates, the sample BP2 with a hierarchical flower-like morphology showed the best degradation efficiency for RhB and 2,4-DCP. The apparent rate constant of sample BP2 in terms of degradation of RhB was nearly 5.7 and 45 times that of unmodified BP0 and N-TiO2. The enhanced photocatalytic performance could be ascribed to synergetic effects including unique hierarchical morphologies, large specific surface area, small particle size, good crystallinity, and suitable band structures. A possible mechanism of catalytic degradation was finally proposed basing upon the active species trapping experiments.

Synthesis, characterization, and visible-light-driven photocatalytic performance of W-SBA15

A series of tungsten-containing mesoporous SBA15 with different tungsten contents were prepared through a direct co-condensation sol-gel method and then analyzed by various techniques. XRD patterns revealed that the original mesoporous morphology was maintained after introducing tungsten species and forms of tungsten species were changed from incorporated tungsten to isolated tungsten species or low oligomeric tungsten oxide species, and finally to crystalline WO3 with the increase of tungsten precursor content, which were also proven by HRTEM images, UV-Vis DRS, and FT-IR spectra. The W-SBA15 samples exhibited satisfactory photocatalytic performance toward degradation of dye Rhodamine B (RhB) and 2,4-dichlorophenol (2,4-DCP). In particular, the best candidate, sample 10%W-SBA15 showed an apparent reaction rate constant for RhB that was nearly 10 times as high as that of bulk WO3. The enhancement of photocatalytic capability was attributed to the mesoporous morphology with enlarged surface areas, negatively charged surface, and favorable tungsten forms such as incorporated tungsten, isolated tungsten or low oligomeric tungsten oxide species. In addition, active radicals trapping experiments and DMPO spin-trapping ESR spectra indicated that photogenerated holes were major oxidative species during photocatalysis.