Prussian blue analogues derived magnetic FeCo@GC material as high-performance metallic peroxymonosulfate activators to degrade tetrabromobisphenol A over a wide pH range

Metal-organic frame (MOF) materials can effectively degrade organic pollutants, whereas the MOF is rapidly hydrolysed in water and has poor stability and low reusability. However, in the current advanced oxidation process (AOP) system, the removal effect of pollutants under alkaline condition is not ideal. In this study, a magnetic composite material derived from MOF was synthesised and used as a new catalyst for rapid degradation of tetrabromobisphenol A (TBBPA). Compared to precarbonisation, FeCo@GC formed a conductive graphite carbon skeleton, retained the complete rhombododecahedron structure, had a larger specific surface area and provided more active sites for peroxymonosulfate (PMS) activation. The target pollutant TBBPA (20 mg/L) was completely degraded within 30 min, and the mineralisation rate reached 40.98% in the FeCo@GC (150 mg/L) and PMS (1 mM) systems, owing to the synergistic interaction between Fe, Co and graphite carbon. The reactive oxygen species (ROS) involved in the reaction were determined to be SO4•-, ·OH, 1O2 and O2•- by electron paramagnetic resonance and free radical scavenging experiments, and the 1O2 played a dominant role. Based on the results of LC-MS analysis results, the main degradation pathways of TBBPA involve three mechanisms: the debromination reaction, hydroxylation and cleavage of the benzene ring. In addition, compared with previous AOP systems, FeCo@GC/PMS overcomes the disadvantage of poor degradation effect of TBPPA under alkaline conditions, has a wide range pH (3-11) application and has the best effect on TBBPA degradation under alkaline conditions. FeCo@GC has an excellent cycle performance, with a removal rate of re-calcined material of 88.52% after five cycles. Therefore, FeCo@GC can be used as a promising and efficient catalyst for removing environmental organic pollutants.

WSe2-loaded co-catalysts Cu3P and CNTs: Improving photocatalytic hydrogen precipitation and photocatalytic memory performance

Photocatalytic decomposition of water for hydrogen production using semiconductor photocatalysts in visible light is considered one of the most promising environmentally friendly ways to produce hydrogen. In this work, the calcination method was adopted to prepare an efficient Cu3P/WSe2/CNTs composite photocatalysts. Cu3P and carbon nanotubes (CNTs) were used as co-catalysts to reduce the composite rate of the photogenerated supports of the photocatalyst. The unique metallic properties of Cu3P as a transition metal phosphide makes it a cost-effective alternative to noble metal co-catalysts. CNTs can serve both as co-catalysts and as a suitable carrier to accelerate the transfer rate of photogenerated electrons. The experimental results showed that the Cu3P/WSe2/CNTs composite photocatalyst exhibited stronger activities in photocatalytic hydrogen production than pure WSe2. In particular, a higher quantum yield of 30.27% at the range 400-700 nm was achieved with a loading of 4% CNTs, a calcination temperature of 300 °C and a calcination time of 2.0 h. In contrast, the quantum yield of pure WSe2 was only 14.01%. The highest hydrogen production rate was 6.987 mL in 4.0 h, and the average hydrogen production rate was 712.985 μmol·h-1g-1, which was 2.39 times higher than that of pure WSe2.The catalytic memory performance of the composite samples was also examined. The results indicated that the best catalytic memory performance was achieved under the pre-illumination condition of 5.0 h. The amount of hydrogen produced under darkness for 4.0 h was up to 4.934 mL and the average hydrogen production rate was 503.454 μmol·h-1g-1. The average hydrogen production rate was 1.69 times higher than the average hydrogen production rate of pure WSe2 under light conditions.

Room-Temperature Benzene Sensing with Au-Doped ZnO Nanorods/Exfoliated WSe2 Nanosheets and Density Functional Theory Simulations

A gold-doped zinc oxide (Au-ZnO)/exfoliated tungsten diselenide (exfoliated WSe₂) nanocomposite-based gas sensor toward benzene with high sensing properties was demonstrated. Epoxy resin was used as the matrix of the Au-ZnO/exfoliated WSe₂ nanocomposite sensor. The straw-shaped Au-ZnO was synthesized by the hydrothermal method, and WSe₂ nanosheets (NSs) were prepared via hydrothermal and liquid-phase exfoliation methods. The properties of Au-ZnO/exfoliated WSe₂ nanoheterostructures constructed by self-assembly technology have been confirmed via a series of characterization methods. The benzene-sensing performances of sensors were tested at 25 °C. Compared with Au-ZnO, WSe_2, and their composites, the Au-ZnO/exfoliated WSe₂ sensor has a significant performance improvement, including a higher response and linear fit degree, better selectivity and repeatability, and faster detection rate. The significantly enhanced sensing properties of the Au-ZnO/exfoliated WSe₂ sensor can be ascribed to the doping of Au nanoparticles, the increase in the specific surface area and adsorption sites of NSs after exfoliation, and the cooperative interface combination of the ZnO/WSe₂ heterojunction. Furthermore, the sensitivity mechanism of the composite sensor to benzene was explored by density functional theory simulations.

Photocatalytic Degradation of Methyl Orange by Magnetically Retrievable Supported Ionic Liquid Phase Photocatalyst

A magnetically retrievable ferrocene appended supported ionic liquid phase (SILP) photocatalyst containing a molybdate anion has been synthesized and characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and vibrating sample magnetometer analysis. The optical properties of the photocatalyst were probed by photoluminescence and UV-vis diffuse reflectance spectroscopy. The discharge of undesirable dye effluents from textile industrial plants in the environment is the major concern of environmental pollution and toxicity. In this context, we employed the as-prepared SILP photocatalyst for degradation of methyl orange (MO) under UV light (365 nm) irradiation, and subsequently, recycling studies were performed. The histological alteration in gills of the fish is employed as a tool for monitoring toxins in the environment. In view of this, the histo-toxicological assessment on freshwater fish Tilapia mossambica gills asserted the damage of secondary gill lamellae due to MO. Conversely, structural modifications in the gill architecture were not observed by virtue of photodegraded products confirming that the degraded product is nontoxic in nature. Additionally, the normal behavior of fishes on exposure to photodegraded products reveals that research findings are beneficial for the aquatic ecosystem.