Ternary NiO/Ag/TiO₂ heterojunction photocatalyst was prepared by deposition coprecipitation for visible light photocatalytic applications. Physicochemical properties of the synthesized NiO/Ag/TiO₂ composite were characterized by X-ray diffraction, Brunauer-Emmett-Teller surface area measurement method, transmission electron microscopy, energy-dispersive X-ray spectroscopy techniques, X-ray photoelectron spectroscopy technique, and ultraviolet-visible absorption spectroscopy. The results suggest that the well-dispersed small metallic silver nanoparticles (<3 nm) facilitate electron transfer and bridge nickel oxide and titanium oxide. The photocatalytic degradation and the methylene blue (MB) dye kinetics were carried out on a ternary NiO/Ag/TiO₂ composite and compared to bare TiO₂ under visible light irradiation. The results indicate that NiO/Ag/TiO₂ has superior MB photodegradation efficiency with a high reaction rate constant and low degradation time (93.15% within 60 min) compared to Ag/TiO₂, NiO/TiO₂, and bare TiO₂. NiO/Ag/TiO₂ nanocomposite was also investigated for the most common pharmaceutical waste degradation and exhibited excellent degradation efficiency. The enhancement of the composite's performance could be attributed to the surface plasmonic resonance of the Ag nanoparticles, the formation of Schottky junctions at the Ag-TiO₂ and Ag-NiO interface, and the p-n heterojunction between NiO and TiO₂. Ag NPs act as a photosynthesizer and a photocatalyst, facilitate electron transfer, shift the absorption to the visible light region, reduce the band gap of TiO₂, suppress the electron-hole recombination, and enhance the photocatalytic activity and stability as a result.

There is a growing demand for new heterogeneous catalysts for cost-effective catalysis. Currently, the hysteresis phenomenon during low-temperature CO oxidation is an important topic in heterogeneous catalysis. Hysteresis provides important information about fluctuating reaction conditions that affect the regeneration of active sites and indicate the restoration of catalyst activity. Understanding its dynamic behavior, such as hysteresis and self-sustained kinetic oscillations, during CO oxidation, is crucial for the development of cost-effective, stable and long-lasting catalysts. Hysteresis during CO oxidation has a direct influence on many industrial processes and its understanding can be beneficial to a broad range of applications, including long-life CO₂ lasers, gas masks, catalytic converters, sensors, indoor air quality, etc. This review considers the most recent reported advancements in the field of hysteresis behavior during CO oxidation which shed light on the origin of this phenomenon and the parameters that influence the type, shape, and width of the conversion of the hysteresis curves.

In this paper, we report oxidation time effect on highly porous silver oxide nanowires thin films fabricated using ultrasonic spray pyrolysis and oxygen plasma etching method. The NW’s morphological, electrical, and optical properties were investigated under different plasma etching periods and the number of deposition cycles. The increase of plasma etching and oxidation time increases the surface roughness of the Ag NWs until it fused to form a porous thin film of silver oxide. AgNWs based thin films were characterized using X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoemission spectroscopy, and UV–Vis spectroscopy techniques. The obtained results indicate the formation of mixed mesoporous Ag₂O and AgO NW thin films. The Ag₂O phase of silver oxide appears after 300 s of oxidation under the same conditions, while the optical transparency of the thin film decreases as plasma etching time increases. The sheet resistance of the final film is influenced by the oxidation time and the plasma application periodicity. Graphic