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.

The role of oxygen in a carbon source (castor oil versus paraffin oil) in the synthesis of carbon nano-onions.

The role of a carbon source containing oxygen groups on the physicochemical properties of carbon nano-onions (CNOs) was investigated. Two oils, castor oil (with O groups) and paraffin oil (without O groups) were converted to CNOs in gram-scale yields using an open flame pyrolysis procedure. The products were heated under argon at 900 °C for varying times (1 h, 2 h, 3 h), to investigate the temperature dependence on their structural properties. TGA studies indicated different decomposition behaviour for the different samples with the annealed paraffinic CNOs (CNOP) having a higher decomposition temperature (>600 °C) than the castor oil derived CNOs (CNOC) (<600 °C). TEM images revealed formation of typical chain-like quasi-spherical nanostructures with particles size distributions for the CNOP (22-32 ± 7.8 nm) and the CNOC (44-51 ± 9.9 nm) materials. A detailed Raman analysis of the CNOs revealed that the graphicity of the CNOs varied with both the carbon oil source and the annealing time. Deconvolution of the first order Raman spectra revealed changes in the parameters of the major Raman bands that were then correlated with defect density ratios. Finally, bandwidth analysis depicted the dependence of the graphicity of the CNOs with heat treatment. The data thus indicate that the presence of oxygen in the carbon source provides a method for producing different CNOs and that simple procedures can be used to produce these different CNOs.

Building carbon structures inside hollow carbon spheres.

The synthesis and characterization of helical carbon nanofibers (CNFs) contained within a fully confined nanoreactor is described. In particular, hollow carbon spheres (od = ca. 310 nm; wall thickness ca. 20 nm) were infiltrated with Cu ions (1%) to produce CuO particles (<10 nm) and the CuO was converted to Cu particles at temperature of 300 °C. Acetylene was then used as a carbon source to grow helical CNFs within the hollow carbon spheres. The diameter and helicity of the CNFs was influenced by the Cu content within a hollow carbon sphere, the limited Cu sintering inside a sphere as well as the dimensions of the sphere. The procedures employed suggest that the philosophy of building other structures (and molecules) with any elements within confined nanoreactors is possible.