Thanh-Truc Pham

Bismuth oxychloride (BiOCl) photocatalysts were synthesized using a simple, cost-effective sol–gel method and integrated with carbon dots (CDs) to form BiOCl@CDs nanocomposites.

Since Pt cocatalysts play an important role in photocatalytic H₂ evolution, it is necessary to track Pt over Pt/g-C₃N₄ catalysts during the evolution process to understand the associated photocatalytic deactivation behavior. In this study, bulk g-C₃N₄ (CN) and oxidized g-C₃N₄ (OCN) catalysts containing a Pt cocatalyst were prepared to investigate photocatalytic deactivation behavior through tracking changes in the catalytic properties of the Pt cocatalyst and g-C₃N₄ surface during photocatalytic H₂ evolution. While CN catalysts show a lower photocatalytic activity than OCN catalysts, the former exhibit high resistance to catalytic deactivation with a lower deactivation rate than the latter. The high photocatalytic activity of OCN catalysts is caused by the highly dispersed Pt species on chemically oxidized g-C₃N₄ with abundant O-containing functional groups, relating to the excellent separation efficiency of photogenerated electron/hole pairs. During the evolution process, highly dispersed Pt species over fresh OCN are easily and rapidly agglomerated into large Pt nanoclusters due to its exfoliated thin-layered g-C₃N₄ structure, whereas the three-dimensional multi-layered g-C₃N₄ structure of CN catalysts hinders the agglomeration of Pt over the CN catalyst. In addition, during the photocatalytic H₂ evolution, the O-containing functional groups on the OCN catalyst significantly disappear, which causes a weak metal/support interaction and, eventually, fast photocatalytic deactivation due to the agglomeration of Pt.

In this study, the BiOCl/rGO (BR) nanocomposites were fabricated via different pathways, BiOCl nanocrystals were directly grown on graphene oxide (GO) sheets and BiOCl nanoflowers and GO were attached after individual fabricated. The basic properties and structures of BiOCl, GO and BR were evaluated by convert infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), Raman scattering spectroscopy and scanning electron microscope (FE-SEM). In this case, the direct growth of BR1S performed stronger linkage between BiOCl and rGO through the chemical interaction of the Bi-C band. That interaction reduced the size of the BR, and showed that the electrons were more excited. Results in the improvement of reaction rate constant 1.45 times higher than the pristine BiOCl, which can totally remove RhB 10 ppm in 30 min.

In this paper, we combined bismuth oxychloride (BiOCl) and graphitic carbon nitride (g-C3N4) to in g-C3N4/BiOCl heterostructure photocatalysts for the rejection of organic contaminants in wastewater. At first, the bulk g-C3N4 was delaminated into a few-layer g-C3N4 suspension in water. Afterward, the photocatalysts were blended via the sol-gel method with the combination of the g-C3N4 suspension at numerous g-C3N4/BiOCl ratios. The methodology, morphology, optical properties, and photocatalytic activity of the g-C3N4/BiOCl series were discussed in detail. The combination of the two-dimensional plate structure of g-C3N4 and BiOCl was examined through scanning electron microscopy (SEM), surface area (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-Vis diffuse reflectance spectroscopy (DRS). Since BiOCl and g-C3N4 are both semiconductors, it is expected that BiOCl sheets will be well dispersed on the surface layers of g-C3N4 to form a heterostructure with the heterogeneous charge transfer model, providing significant removal of Rhodamine B (RhB) dye under visible light. Such a combination has the potential to overcome the disadvantages of pristine BiOCl and g-C3N4 improve the photocatalytic activity, and shorten the wastewater treatment time.

In this study, a nanocomposite film comprising poly(vinyl alcohol) (PVA) and rice husk-derived cellulose nanocrystals (CNC) was introduced as a novel sorbent for removing copper (II) cations. First, CNC was isolated from neat rice husk, and then these particles with many ratios compared to PVA (2, 4, 6, and 10 wt.%) were added to the PVA solution to render the nanocomposite films. The obtained films were evaluated using scanning electron microscopy, Fourier-transform infrared spectroscopy, and water uptake tests. The optimal condition for the sorbent preparation was 10 wt.% of CNCs to PVA. The maximum ion adsorption percentage of the PVA/CNC 10 % film reached 55 % after 3 h exposure to 70 ppm Cu (II) ion solution at 25 °C. This research suggested a facile and feasible fabrication method of a nanocomposite film, considered a potential sorbent for the adsorption of copper (II) ions.

Co-doped NiTiO₃/g-C₃N₄ composite photocatalysts were prepared by a modified Pechini method to improve their photocatalytic activity toward methylene blue photodegradation under visible light irradiation. The combination of Co-doped NiTiO₃ and g-C₃N₄ and Co-doping into the NiTiO₃ lattice synergistically enhanced the photocatalytic performance of the composite photocatalysts. X-ray photoelectron spectroscopy results for the Co-doped NiTiO₃/g-C₃N₄ composite photocatalysts confirmed Ti-N linkages between the Co-doped NiTiO₃ and g-C₃N₄. In addition, characteristic X-ray diffraction peaks for the NiTiO₃ lattice structure clearly indicated substitution of Co into the NiTiO₃ lattice structure. The composite structure and Co-doping of the C-x composite photocatalysts (x wt % Co-doped NiTiO₃/g-C₃N₄) not only decreased the emission intensity of the photoluminescence spectra but also the semicircle radius of the Nyquist plot in electrochemical impedance spectroscopy, giving the highest k_app value (7.15 × 10⁻³ min⁻¹) for the C-1 composite photocatalyst.