Room temperature sensing of primary alcohols via polyaniline/zirconium disulphide.

Among the primary alcohols, ethanol is referred to as a heavy chemical due to its many applications in a variety of industries. Detection of primary alcohols can be deployed as a non-invasive method in medical diagnosis and safety measures in food processing companies. Zirconium disulphide is a novel 2D layered material with exotic features when in mono or few layers, which include fast electron transport, high carrier mobility and sizeable band gap. ZrS2 and PANI were fabricated using liquid exfoliation and chemical polymerization methods respectively. Functionalization of the conducting polyaniline with ZrS2 was done using facile sonication process. The sensor showed good sensitivities (43%, 58% and 104%) which were estimated from slopes of the linear fitted plots with fast response-recovery times of 8 s and 27 s (111 ppm); 12 s and 130 s (77 ppm); and 58 s and 88 s (58 ppm). Good reproducibility at three repeated measurements (111 ppm, 77 ppm and 58 ppm) was also observed for methanol, ethanol, and isopropanol vapours respectively. Meanwhile, the sensor displayed more linearity and sensitivity towards isopropanol compared to methanol and ethanol. The sensor showed good performance even at RH values close to 100% making it a potential alcohol breath analyser.

Fabrication of Hierarchical Two-Dimensional MoS2 Nanoflowers Decorated upon Cubic CaIn2S4 Microflowers: Facile Approach To Construct Novel Metal-Free p-n Heterojunction Semiconductors with Superior Charge Separation Efficiency.

Due to the enormous demand for effective conversion of solar energy and large-scale hydrogen production, cost-effective and long-lasting photocatalysts are believed to be necessary for global production of sustainable and clean hydrogen fuel. Robust and highly efficient p-n heterojunction photocatalysts have a striking ability to enhance light-harvesting capacity and retard the recombination of photoexcitons. A series of p-MoS2/n-CaIn2S4 heterojunction composites with different MoS2 contents have been synthesized via a facile two-step hydrothermal technique in which rose-like p-MoS2 nanoflowers are decorated upon n-type cubic CIS microflowers. In the synthesis protocol highly dispersed MoS2 nanoflowers provided more active edge sites for the growth of c-CIS nuclei, leading to a hierarchical architecture with intimate interfacial contact. The formation of a hierarchical flower-like morphology of the photocatalyst has been established by an HRTEM and FESEM study. Electrochemical characterization, especially the slope of the curve from Mott-Schottky analysis and nature of the current from LSV, reveals the p-n heterojunction nature of the composite photocatalyst. The fabricated heterojunction photocatalysts were further examined for visible light photocatalytic H2 evolution. Far exceeding those for the neat c-CIS and MoS2, it is seen that the p-MoS2/n-CIS heterojunction photocatalyst with an optimum content of MoS2 exhibited enhanced H2 evolution using a 0.025 M Na2S/Na2SO3 solution as hole quenching agent under visible light illumination. The 0.5 wt % p-MoS2/n-CIS photocatalyst presents a higher H2 production rate of 602.35 µmol h-1 with 0.743 mA cm-2 photocurrent density, 19 times and 8 times higher than those of neat c-CIS, respectively. This superior photocatalyic activity is due to the efficient separation of electron-hole charge carriers at the interface, as supported by a photoluminescence study and EIS measurements.

Synthesis and application of pillared clay heterogeneous catalysts for wastewater treatment: a review.

The use of pillared interlayered clays (PILCs) as heterogenous catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), is gaining popularity for the treatment of refractory wastewater effluents. The recent literature involving these solid materials is reviewed, with more focus on studies that aim at reducing the synthesis costs and escalating the synthesis process to industrial scale. Their role as active solid materials in the AOPs such as photocatalysis, catalytic wet peroxide oxidation (CWPO), the Fenton process and catalytic wet air oxidation (CWAO) of refractory organic compounds in polluted aqueous streams is also reviewed. These processes are evaluated to evidence their main direction for future research, particularly with reference to possible industrial use of these technologies to treat refractory organic wastewater using pillared clay-based catalysts. The pillared clay catalysts demonstrate good application prospects for the removal of refractory wastewater effluents using AOP technology. The reviewed studies suggest that the photocatalytic process is useful in low concentrations of these compounds, while CWPO, the Fenton process and CWAO are recommended for higher concentrations. However, catalyst development to reduce the severity of oxidation reaction conditions, with focus on the low cost, catalyst stability, reusability and environmental friendliness are the key aspects to be addressed by future research work.

Synthesis and characterization of an efficient and stable Al/Fe pillared clay catalyst for the catalytic wet air oxidation of phenol.

A facile method for synthesizing Al/Fe pillared clays (PILCs) from natural bentonite clay, by using ultrasonic treatment during the aging and intercalation steps, has been established. Single metal (Fe-PILCs and Al-PILCs) and mixed metal (Al/Fe-PILCs, with varying compositions of the pillaring precursors) pillared clays were prepared and characterized with a combination of chemical and instrumental methods. The pillared clays were evaluated as catalysts in the catalytic wet air oxidation (CWAO) of phenol and the mixed metal pillared clay catalysts, especially with an Al/Fe ratio of 3 : 1, were found to be highly active and stable, with superior properties such as surface areas, basal spacing, high porosity and thermal stability. The catalysts could also be reused several times without significant loss of activity. The results of the study show that Al/Fe-pillared clay catalysts are effective catalysts for the oxidation of phenol and removal of TOC in aqueous solutions. The main intermediate products in the CWAO of phenol were hydroquinone, pyrocatechol, and benzoquinone and oxalic, formic, malonic, oxalic, malonic and maleic acids.

Dramatic promotion of gold/titania for CO oxidation by sulfate ions.

The activity of gold/titania catalysts for the room-temperature oxidation of CO can be dramatically enhanced by the addition of sulfate ions to the support; it appears that anion promotion of gold may be a general phenomenon and may be related to the direct modification of active gold sites in the case of sulfate ions, as evidenced by secondary ion mass spectrometry.