Xiaowei Wang

Fe‐doped ZnO ceramic nanofibers (CNFs) as specific structural features and unique properties synthesized by using electrospun technology. X‐ray diffraction disclosed the wurtzite phase, and the microscopy analysis by SEM revealed the formation uniform nanofibers with 400 nm in diameter. The UV–visible diffuse reflectance spectroscopy (DRS) was used to investigation the optical properties of the pristine and the various percentages Fe doped ZnO photocrystalysts. The photo‐reduction activities of photocatalyst were evaluated using methylene blue (MB) as organic contaminant irradiated with simulate solar light from xenon lamp. The photocatalytic results that 1% Fe‐doped ZnO CNFs exhibits efficient visible and UV light activity and excellent photo‐stability. The kinetic constant of MB degradation over 1% Fe‐doped ZnO is about 2.2 times higher than that over pure ZnO. The experiment demonstrated that the photodegradation efficiency of Fe‐doped ZnO was significantly higher than that of undoped ZnO.

In this study, the magnetic urchin‐like NiCo₂O₄ materials (NiCo₂O_4‐w) were successfully prepared from the waste during the preparation of NiCo₂O₄/carbon cloth composite, and further evaluated as a peroxymonosulfate activator for removing bisphenol A (BPA). The effect of various factors such as initial solution pH, peroxymonosulfate (PMS) concentration, catalyst concentration, and coexisting ions on the BPA removal were evaluated. The optimal factors were 0.20 g L⁻¹ catalyst, 0.10 g L⁻¹ PMS, 7.14 pH (unadjusted). Moreover, the NiCo₂O₄‐w exhibited good catalytic effects over wide ranges of pH (3.73 to 12). SO₄²⁻ and H₂PO₄⁻ remarkably inhibited the BPA removal, NO₃⁻ obviously inhibited the BPA removal, while Cl⁻ and HCO₃⁻ had a little effect on the BPA removal. Singlet oxygen (¹O₂), superoxide radical (O₂^•−), hydroxyl radical (^•OH) and sulfate radical (SO₄^•−) participated in the BPA degradation, of which O₂^•− and ¹O₂ played the leading role, especially O₂^•−. Oxygen vacancies, redox cycling pairs of Co(III)/Co(II) and Ni(III)/Ni(II) were responsible for PMS activation. Moreover, the degradation routes of BPA were rationally put forward. This present work not only presents that NiCo₂O₄‐w has a low‐cost, magnetically recoverable catalyst for high efficient degradation of wastewater containing BPA, but also opens up a new avenues to reduce environmental problems associated with waste treatment during the preparation of heterogeneous catalyst.

Graphitic carbon nitride (g‐C₃N₄) is a fascinating nonmetallic photocatalyst for the removal of environmental pollutants. The fumed silica/g‐C₃N₄ (gCN‐FS) composite photocatalysts were successfully fabricated by a combination of solvent volatilization and post‐annealing methods. The introduction of SiO₂ not only widens the absorption range of visible light, but also enhances the specific surface area of g‐C₃N₄. The gCN‐FS‐3 composite has a BET surface area of 129.89 m²/g, which is ~3.3 times as much as that of g‐C₃N₄ (39.54 m²/g). The gCN‐FS composites have markedly improved rhodamine B (RhB) photodegradation activity in comparison to pure g‐C₃N₄, bulk g‐C₃N₄ and P25 under 557 nm yellow‐green light emitting diode light irradiation. The gCN‐FS‐3 has the highest RhB photodegradation rate, which is ~9.67‐, 11.81‐folds as compared to bare g‐C₃N₄ and bulk g‐C₃N₄, respectively. The coupling effect between the increase in specific surface areas and the inhibition effect of SiO₂ on photogenerated electron/hole pairs recombination is responsible for the enhanced visible light photocatalytic activity of gCN‐FS composite. Superoxide and holes are responsible for the RhB photocatalytic degradation. Furthermore, no apparent loss of photocatalytic activity over five cycles is observed, which indicates that the gCN‐FS composites have considerable stability and reusability in the photodegradation process. The gCN‐FS composites show great promise in visible light driven photocatalysis for environmental applications.