A two-dimensional layered CeO₂/Bi₂O₃ composite was synthesized by microwave solvothermal method. X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), UV-Vis diffuse reflection spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) were used to studied crystal structure, morphology, optical performance, elemental composition and the surface electronic state of the samples. The photocatalytic properties of the prepared samples were evaluated by photocatalytic desulfurization under visible light. When the molar ratio of Ce and Bi was 1:2, CeO₂/Bi₂O₃ composite presented the highest photocatalytic desulfurization rate. Transient Photocurrent measurement, electrochemical impedance spectroscopy (EIS) and photoluminescence spectroscopy (PL) showed that CeO₂ and Bi₂O₃ formed a heterojunction, which could promote the separation of photogenerated electrons and holes, improving the photocatalytic activity. Furthermore, it was found that the active species of hydroxyl radical (·OH) played an important role in the photocatalytic degradation of dibenzothiophene (DBT) based on the active species capture experiment. Finally, a plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite was proposed.

The existence of an HCP phase in FCC-type high-entropy alloys can improve the alloy’s mechanical properties. In many cases, an HCP phase is induced by deformation. In the present work, an FCC to HCP transition was detected during the cooling of Co_1.5CrFeMnNi_0.5 and Co_1.75CrFeMnNi_0.25 alloys. Therefore, arc-melted annealed Co_xCrFeMnNi_2−x (x = 0.25–1.75) alloys that were then subjected to long-term vacuuming were investigated using XRD, DSC, HT-XRD, thermodynamic calculation, and first-principle calculation. It was confirmed that the FCC to HCP transition occurred at ~450 °C during the cooling of the alloys with x ≥ 1.5. The volume fraction of the HCP phase increased with Co content. It was proven that the HCP phase was not stable above 600 °C. First-principle calculations further indicated that the HCP structure was more stable than the FCC structure for Co_1.75CrFeMnNi_0.25 alloy, and there was a likelihood of an FCC to HCP transition. Moreover, experimental tests confirmed that the microhardness of the Co_1.75CrFeMnNi_0.25 alloy reached 213 HV because it contained a substantial HCP phase. This value is much higher than those of other non-HCP-containing alloys, either in their as-cast states or after annealing. These results provide guidance for the design of FCC-type high-entropy alloys with desirable mechanical properties through HCP phase strengthening.

The development of efficient heterojunction photocatalysts with a facilitated charge carrier separation rate and improved light-harvesting capacity is still a challenging issue for effectively solving environmental pollution. Herein, a one-step refluxing process was employed to construct 2D/2D CdIn₂S₄/In₂S₃ (CISI) heterojunction photocatalysts with an intimate interface between these two components. The crystal structure, morphology, light-harvesting capacity, and Cr(VI) photoreduction performance were systematically investigated and discussed in detail. The tight interface formed between CdIn₂S₄ (CIS) and In₂S₃ (IS) could effectively facilitate the charge carrier separation and transfer. Thus, the resulting CISI composites exhibited a high efficiency for Cr(VI) photoreduction under visible light, with the optimal sample of 0.5 CISI. The charge transfer kinetics were deeply investigated by multiple techniques. Based on the characterization results, a possible mechanism for Cr(VI) photoreduction was proposed.

CdS nanoparticles were constructed onto one-dimensional (1D) CeO₂ nanorods by a two-step hydrothermal method. The X-ray diffraction (XRD), transmission election microscopy (TEM), Raman spectra, X-ray photoelectron spectra (XPS) and UV-Vis diffuse reflection spectroscopy (DRS) techniques were used to characterize these CdS/CeO₂ nanocomposites. It was concluded that when the molar ratio of CdS and CeO₂ was 1:1, the nanocomposites exhibited the best photocatalytic desulfurization activity, reaching 92% in 3 h. Meanwhile, transient photocurrent (PT) measurement, photoluminescence (PL) spectra and electrochemical impedance spectroscopy (EIS) measurement indicated that the modification of CeO₂ nanorods by CdS nanoparticles could significantly inhibit the recombination of photogenerated electrons and holes. In addition, the possible mechanism of photocatalytic oxidation desulfurization of the nanocomposites was proposed. This study may provide an effective CeO₂-based photocatalyst for photocatalytic desulfurization applications.

An increase of carrier concentration is one of the most important routes for enhancing the catalytic performance of semiconductor photocatalysts. In this study, the Sillén–Aurivillius oxychloride Bi₄NbO₈Cl with hole doping was successfully prepared by a solid-state reaction method. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible diffuse reflectance spectra (UV–vis DRS), X-ray photoelectron spectrometry (XPS) and photoluminescence spectra (PL) were used to characterize and analyze the prepared samples. The experimental results and density functional theory calculations demonstrate that hole doping can be formed in Bi₄NbO₈Cl by inserting zinc into the niobium site, and the photocatalytic activity can be improved by introducing additional holes into Bi₄NbO₈Cl. The photogenerated hole (h⁺) is considered to be the main active species to degrade trypan blue (TB) through trapping experiments. The optimal photocatalyst of Bi₄Nb_0.8Zn_0.2O₈Cl exhibits excellent photocatalytic activity in degradation of trypan blue under visible light irritation. Moreover, a possible photocatalytic degradation mechanism is discussed according the experimental and analytical results.