ZhongT Jiang

The interplay of aromatic molecules with 3d transition metals, such as Fe and Cu, and their oxide surfaces provide important fingerprints for environmental burdens associated with thermal recycling of e-waste. Previous DRIFTS and EPR measurements established a strong interaction of the phenol molecule with the metal oxides via the formation of phenolic and catecholic intermediates. In this contribution, we comparatively examined the adsorption of phenol molecule, as a representative model for oxygen-containing components on pure metallic surfaces and their partially oxidized surfaces through accurate density functional theory (DFT) studies. In particular, it is the aim of elucidating the specific underlying mechanism of these reactions as well as to unravel the catalytic effect of these different substrates. Simulated results show that, the phenol molecule undergoes partial hydrogenation to generate phenoxy-type adduct mediated by the metallic surfaces. Investigation found that the phenol physisorbed adapts on the pure Cu and Fe surfaces are very weak; with the binding energies of -2.4 and -2.1 kcal/mol compared to -3.1 and -5.5 kcal/mol for their partially oxidized surfaces, respectively. Molecular attributes based on charge transfer and geometrical features provide an insightful explanation into these energetic trends. Furthermore, the thermo-kinetic parameters established over the temperature region of 300 and 1000 K, exhibit a lower activation energy for phenol decomposition into phenoxy group over the oxide surfaces in reference to their pure surfaces (24 and 43 kcal/mol vs 38 and 47 kcal/mol). Clearly, vacancies on pure metallic surfaces substantially reduce the activation energies required in the fission of the phenolic’s O-H bonds.

Poly (vinyl chloride) (PVC) plastic represents an indelible fraction of electronic devices. Among various treatment methods, co-pyrolysis of PVC with metal oxides, particularly (iron oxide), constitutes an appropriate disposal technique from the point view of enviromnental safeguard or energy recovery. It has been found that Fe20 3 nanoparticles absorb and dissociate HCI molecules and form a cluster-molecule adduct with a small activation barrier of 10.6 kcal mor1 • Theoretical aspect of adsorption behaviors ofHCI over Fe20 3 cluster agree relatively well with recent experimental studies: underlying formation of iron chlorides during interaction of HCI and iron oxides [I]. This contribution provides a systematic theoretical kinetic study of the initial interplay of hematite nanopatiicles with chlorine-bearing compounds (namely as hydrogen chloride, chloroethene, 1- chloro-1-propene, chloroethane, 2-chloropropane, chlorobenzene and 2-chlorophenol) that are released from the degradation of PVC. A detailed kinetic analysis points out that, subsequent addition of HCl to Fe(Cl)-O(H) structures leads to convert Fe20 3 into oxychlorines and iron chlorides. Then, elimination of HzO molecule proceeds via an intramolecular hydrogen transfer. The analyses of the transition structures indicate that, there are two possible pathways to operate in the reaction of chlorinated alkanes and alkenes with a-Fe20 3 clusters, i.e., direct elimination and dissociative addition. These two pathways assume competing significance in formation of acetylene from vinyl chloride. Results from this study should be instrumental to understand on a precise molecular basis fixation of halogens on transitional metal oxides; a viable recycling options for polymeric materials laden with halogenated constituents.

Magnetron sputtered CrN based coatings have wide use of applications as protective coatings for cutting/machining tools that require higher thermal/chemical stability and superior mechanical properties at high temperatures [1]. Incorporation of AI[2], Si[3], and Ni[4] to the binary CrN structure can substantially improve their mechanical propetiies. However, measurements of the mechanical properties at high temperatures are very difficult or impossible to obtain due to instrumental limitations. The aim of this study is to predict the mechanical properties of CrSiN and CrNiN coatings, from in-situ Synchrotron Radiation X-ray Diffraction (SR-XRD) measurements exposed at high temperatures (25 °C to 700 °C). Rietveld refinement of the SRXRD, using TOP AS software, data on the phase compositions, crystallite sizes, microstrain and residual stresses of these coatings were analysed. Similarly Nanoindentation measurements, at room temperature, were undetiaken with all of these coatings. Analysis of the refinement and nanoindentation data indicate that Si-dopants effectively lowers crystalline growth and stress release in the coating lattice as temperature is increased to 700 oc and as a result the thermal stability of the coating is remarkably enhanced. However, Ni doping was unsuccessful in stabilizing the crystal structure of CrN coatings at elevated temperatures. In conclusion, high hardness of CrSiN and reduction of hardness for CrNiN coatings, after annealing to temperatures up to 700 °C, is confirmed by the microstructure analyses from SR-XRD data in combination with Nanoindentation measurements.

Transparent electronics are an essential ingredient in many new technologies which are emerging in the 21st century - high efficiency solar cells[ll, interactive and transparent displays, energy efficient windows, and photonics for communications and computing[2J. The development of functionalised transparent conductive oxide materials (TCOs), in terms of abundant, cheap and environmentally friendly, is critical for materials science in such applications. Specifically, an impmiant research goal is to find substitutes for the dominant TCO material indium tin oxide (ITO), made from indium which is scarce, expensive and toxic. Zinc oxides doped with small amounts of aluminium (AZO), are promising candidates for such a substitute but generally don't perform as well as IT0[2l. Gallium co-doping with aluminium improves AZO performance significantly, but raises similar concerns to ITO, in terms of the scarcity and high cost of gallium. This project aims to enhance the conductivity of AZO thin films-by adding a thin 'seed' layer co-doped with AI and minimum Ga concentration (AGZO). The project employed solution based sol-gel technique for synthesising AZO/GZO nanoparticles and then deposited on glass substrates through a spin coating process, followed by thermal annealing treatment. The optical properties, crystal structure and surface morphology of the films were characterised using UV-vis spectroscopy, X-ray diffraction and scanning electron microscopy. Composite multilayer films, with thickness around 400nm, exhibit transmittance above 90% across the visible range and resistivity approximately 10 O•cm. Preliminary results indicate significant improvement in AZO films with the co-doped AGZO layer, compared with AZO films alone. Compared to uniformly doped AGZO films, the composite multilayer films exhibited similar performance, but with only 20% of the gallium consumed.

Among various transparent conductive materials, indium tin oxide (ITO) demonstrates a major dominant role due to its high optical transparency and high electrical conductivity. Doping ITO with a transition metal, such as Ti, Mo, Zr, Cu, can improve the optoelectronic properties of such coatings. In this study, titanium- doped ITO (Ti:ITO) thin film coatings were developed via a low cost and simple sol-gel spin coating technique. The effect of Ti concentration and annealing temperature on the structural, morphological, optical and electrical properties of the synthesized films (350nm thickness) were characterised by FESME, XRD and UV-Vis techniques. XRD analysis confirmed the cubic bixbyite structure of polycrystalline indium oxide phase. The crystallinity, optical transparency and electric conductivity of the thin film coatings were improved with increase of annealing temperature. At 500°C annealing temperature the grain sizes, verified by FESEM, of the thin films were 79 and 65 nm for doping concentration of 4 at% and 2 at% Ti, respectively. Furthermore, at this temperature, optimum electrical resistivity (1.6x 10-4 n.cm) and optical transmittance (92%) were achieved. These results compare favourably with the resistivity (2.9x 1 o-4 n.cm) and transparency around (90%) founded by Liu et.al and Paeng et. al respectively [1, 2].

In recent years, researchers around the world are paying substantial efforts for the development of transition metallic nitride based solar selective surfaces due to a good combination of many properties e.g., large band-gap, excellent chemical and thermal stability, corrosion resistance, wear resistance, oxidation resistance and physical robustness. Further applications of transition metal nitride based films also include: spintronics, nonvolatile storage, microelectronic/optical/optical storage devices. In view of these facts, research interests on transition metal nitride based films have been accelerated and dedicated to the development of new species studying their properties to find potential applications in other areas. In the present study, Mo, CrN, and Mo-doped CrN (CrN:Mo) films synthesized via closed field unbalanced magnetron sputtering technique were characterised using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy to study their structural,• surface morphological and optical properties. This includes prope1iies such as solar absorptance, thermal emittance, solar selectivity, complex refractive index, and complex dielectric functions. The chemical composition of these films was confirmed by EDS measurement. Structural disorder was observed in XRD spectra depending on the Mo incorporation to the CrN matrix. The XRD studies indicated crystallinity of the Mo and CrN phases were substantially increased in the CrN:Mo films and also confirmed via FESEM studies. UV-Vis spectrum (190-2500nm) of the CrN:Mo films demonstrate the highest value of solar absorptance (61%) while a substantial decline from 31.5% (CrN) to 5.6% (CrN:Mo) in the thermal emittance value, from FTIR (2.5 - 20 Jlm). Consequently, the CrN:Mo films exhibited the highest solar selectivity value of 9.55. Inclusive to the optical properties given above, the dielectric propetiies of these films were also investigated from the UV-Vis and FTIR results.

Photothermal devices require high performance solar selective materials for the surface of solar energy converters. A good solar selective surface exhibits high spectral absorptance in the visible range and low thermal emittance in the infrared to far-infrared range of the solar spectrum. 3d transition metal oxide based thin film coatings are explored as high solar selective material to be used in solar energy harvesting devices. Solar selectivity of such coatings depends on the deposition conditions, crystal structure, chemical composition, microstructural morphology, composition uniformity and stoichiometry. This report highlights and summarizes the optical properties and mechanical characteristics of some recently developed sol-gel dip coating derived from CuxCoyOz transition metal oxides based solar selective surfaces thinfilms. X-ray photoelectron spectroscopy (XPS), UV-Vis spectrometer, FTIR spectrophotometer, nanoindentation and Synchrotron radiation X-ray diffraction (SR-XRD) techniques are utilized to realize various Features Involved in such coatings.