Photocatalytic degradation research has attracted significant attention in the wake of the increasingly severe global challenge of water pollution. In this study, nano-ZnO was synthesized through a straightforward method using zinc acetate anhydrous as the precursor. The experimental results revealed that annealing conditions significantly influenced the bandgap energy (Eg) of ZnO, with a positive correlation observed between the intensity of photoluminescence (PL) spectra and photocatalytic activity. Under optimal annealing conditions at 300 °C for 1.5 h, the photocatalytic degradation efficiency of methylene blue (MB) exceeded 98% within 40 min of ultraviolet (UV) irradiation, surpassing the efficiencies reported for ZnO in recent studies. This high performance underscores the excellent photocatalytic activity of the synthesized ZnO samples. Furthermore, after five photocatalytic cycles, the degradation efficiency of MB remained above 90%, and the crystalline structure of the ZnO samples remained stable, demonstrating their exceptional structural stability during the photocatalytic process. Additionally, this study examined the effects of stirring conditions and different light sources on MB degradation, providing valuable insights for future research in related fields.

Persistent organic pollutants pose significant long-term risks to environmental and human health due to their carcinogenic, mutagenic, and teratogenic properties. This study focuses on the efficient activation of peroxymonosulfate (PMS) through the rational design of a cobalt-based metal–organic framework (ZIF-67) catalyst, enabling rapid degradation of high-concentration dye pollutants. By optimizing the molar ratio of 2-methylimidazole (2-MeIM) to Co(NO₃)₂·6H₂O and employing a hydrothermal synthesis method, we fabricated ZIF-67 (4 : 1) with high crystallinity, large specific surface area (1656.68 m² g⁻¹), and stable degradation performance. The ZIF-67 (4 : 1)/PMS system achieved complete degradation of 20 mg L⁻¹ and 100 mg per L Rhodamine B (RhB) within 60 seconds and 6 minutes, respectively, surpassing recent reported efficiencies. The system also maintained high activity over a broad pH range (3–9). Radical quenching experiments and electron paramagnetic resonance (EPR) analysis identified sulfate radicals (˙SO₄ ⁻ ₄) and singlet oxygen (¹O₂) as the dominant reactive species. Furthermore, the catalyst exhibited excellent recyclability with no significant loss in activity after five consecutive cycles. This work provides a facile and scalable strategy for preparing highly active cobalt-based catalysts, demonstrating great potential for practical applications in industrial wastewater treatment and environmental remediation.

This study explores the fabrication of ZnO-SiO₂ composite films on silicon substrates via a sol–gel method combined with spin-coating, followed by annealing at various temperatures. The research aims to enhance the UV emission and photoelectric properties of the films. XRD showed that the prepared ZnO sample has a hexagonal structure. SEM images revealed the formation of ZnO nanorods within a dense SiO₂ substrate, ranging from 10 μm to 30 μm in length. Photoluminescent analysis showed that the film exhibited strong UV emission centered at 360 nm. The response time measurements indicated that the optimal photoresponse time was approximately 2.9 s. These results suggest the potential of ZnO-SiO₂ films as efficient UV-emitting materials with high photoconductivity and a stably reproducible response under visible light, thereby laying the foundation for their application in advanced optoelectronic devices.

La-doped ZnO nanoclusters confined within mesoporous SBA-15 were synthesized using an impregnation–calcination method and evaluated for their visible-light-driven photocatalytic degradation of Rhodamine B (RhB). Small-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the preservation of the 2D hexagonal mesostructure of SBA-15 post-loading. In contrast, wide-angle XRD and Fourier-transform infrared spectroscopy (FT-IR) analyses revealed that the incorporated ZnO existed predominantly as highly dispersed amorphous or ultrafine clusters within the mesopores. N₂ adsorption–desorption measurements exhibited Type IV isotherms with H1 hysteresis loops. Compared to pristine SBA-15, the specific surface area and pore volume of the composites decreased from 729.35 m² g⁻¹ to 521.32 m² g⁻¹ and from 1.09 cm³ g⁻¹ to 0.85 cm³ g⁻¹, respectively, accompanied by an apparent increase in the average pore diameter from 5.99 nm to 6.55 nm, attributed to non-uniform pore occupation. Under visible-light irradiation, the photocatalytic performance was highly dependent on the La doping level. Notably, the 5% La-ZnO/SBA-15 sample exhibited superior activity, achieving over 99% RhB removal within 40 min and demonstrating the highest apparent rate constant (k = 0.1152 min⁻¹), surpassing both undoped ZnO/SBA-15 (k = 0.0467 min⁻¹) and other doping levels. Reusability tests over four consecutive cycles showed a consistent degradation efficiency exceeding 93%, with only a ~7 percentage-point decline, indicating excellent structural stability and recyclability. Radical scavenging experiments identified h⁺, ·OH, and ·O₂⁻ as the primary reactive species. Furthermore, photoluminescence (PL) quenching observed at the optimal 5% La doping level suggested suppressed radiative recombination and enhanced charge carrier separation. Collectively, these results underscore the synergistic effect of La doping and mesoporous confinement in achieving fast, efficient, and recyclable photocatalytic degradation of organic pollutants.

In this research, anatase-phase SiO₂@TiO₂ spherical photocatalysts were prepared via sol–gel method. Calcination parameters, catalyst dosage, and degradation performance toward RhB and various pollutants were systematically investigated.

Organic pollutants such as dyes and pharmaceuticals pose serious threats to aquatic ecosystems and human health, highlighting the need for efficient advanced oxidation processes. Here, oxygen-doped graphitic carbon nitride was synthesized by co-calcination of melamine and cyanuric acid and applied to a photoactivated peroxymonosulfate system. Comprehensive characterizations combined with density functional theory calculations revealed that oxygen incorporation induces charge redistribution and improves the surface structure, leading to enhanced visible light absorption and charge separation. Under simulated sunlight, the catalyst achieved 99% degradation of rhodamine B (30 mg/L) within 6 min, with a reaction rate 14 times higher than that with pristine carbon nitride. Reactive species trapping and electron paramagnetic resonance analyses confirmed that singlet oxygen and superoxide radicals dominate the degradation process. The catalyst also exhibited good stability over five cycles. This work provides an effective strategy for designing metal-free photocatalysts for peroxymonosulfate activation and wastewater treatment.