Synthesis and Enhanced Light Photocatalytic Activity of Modulating Band BiOBrXI1-X Nanosheets

Using rice husk ash as a SiO2 source in the preparation of SiO2/Nb2O5 and SiO2/ZnS heterostructures for photocatalytic application

This work presents the synthesis of SiO₂/Nb₂O₅ and SiO₂/ZnS heterostructures using the microwave-assisted hydrothermal (MAH) method, which is fast and has low temperature. The silica used in the synthesis was obtained by burning the rice husk without any pre- or post-treatments. The obtained samples were characterized using various techniques such as X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and UV-visible. The obtained silica was found to be amorphous, and the materials used for modification showed characteristic of the type of synthesis used. SEM images showed that Nb₂O₅ and ZnS interacted with the SiO₂ surface, filling the voids. In the photocatalytic process, the heterostructures showed enhanced decolorization efficiency for dyes such as rhodamine B (RhB) and methylene blue (MB) compared to SiO₂. For RhB, the silica decolorized approximately 24%, and for MB, it discolored approximately 27%; SiO₂/Nb₂O₅ showed 91.24% decolorization efficiency for RhB and 72.77% MB, while SiO₂/ZnS showed approximately 96% for RhB and 100% for MB. All samples were tested under the same conditions. This demonstrates that the use of rice husk residue not only improves the photocatalytic activity of heterostructures but also promotes the utilization of improperly discarded residues.

Synthesis and Use of Silica Xerogels Doped with Iron as a Photocatalyst to Pharmaceuticals Degradation in Water

The main objective of this study was to assess the photoactive properties of iron-doped silica xerogels under solar radiation. For this purpose, silica xerogels (XGS) synthesized by the sol-gel method were doped with Fe (III) by two routes: impregnation and polymerization. XGS samples were texturally and chemically characterized by N2 adsorption, XRD, FTIR, Raman, SEM-EDX, DRS, and PL, evidencing the suitability of using XGS substrates to host iron clusters on their surface with total compatibility. Chlorphenamine (CPM), ciprofloxacin (CIP), and ranitidine (RNT) were used as model compounds. The degradation of the molecules was made under simulated solar radiation testing the synthesis pad, load, material size, and reuse. It was found that XGS doped with Fe by the impregnation route (XGS-Fe-Im) were able to completely degrade CPM and RNT in 30 min and 10 min, respectively, whilst for CIP it achieved the removal of 60% after 1 h of solar radiation exposure, outperforming parent materials and solar radiation by itself. The study of the degradation mechanism elucidated a major influence from the action of HO• radicals. The present investigation offers a potential route of application of XGS Fe-doped materials for the removal of emerging concern contaminants under near real-world conditions.

Fabrication of a Heterobinuclear Redox Cycle to Enhance the Photocatalytic Activity of BiOCl

La3+ and Ni2+-doped BiOCl were prepared by sol–gel method and characterized by physicochemical and spectroscopic techniques. Their photocatalytic performances were investigated by the degradation of gentian violet under visible light. The results indicated that the co-doping of Ni and La significantly enhanced the photocatalytic performance of BiOCl. The photodegradation efficiency of LaNiBiOCl reached 95.5% in 105 min, which was 1.5 times that of BiOCl. This significant enhancement in photocatalytic activity was mainly attributed to the effective capture and transfer of photogenerated electrons between heterobinuclear La and Ni redox cycle, which benefited the photodegradation of active h+ and the formation of active •O2−. Furthermore, the photodegradation activity did not show an obvious drop after five recycles, indicating that LaNiBiOCl was a promising semiconductor photocatalyst for the degradation of gentian violet.