64 research outputs found
Crossing the divide between homogeneous and heterogeneous catalysis in water oxidation
An atomic layer deposition (ALD) procedure is described for stabilizing surface binding of a water oxidation catalyst to the surfaces of nanostructured films of indium tin oxide. The catalyst is stabilized on the surface of electrodes by ALD of an overlayer of TiO2. Stabilization of surface binding allows use of basic solutions where a rate enhancement for water oxidation of ∼106 is observed compared with acidic conditions. There are important implications for stabilizing surface-bound molecular assemblies for applications in dye sensitized solar cells, electrocatalysis, and photoelectrocatalysis
Solar water splitting in a molecular photoelectrochemical cell
Solar water splitting into H2 and O2 with visible light has been achieved by a molecular assembly. The dye sensitized photoelectrosynthesis cell configuration combined with core–shell structures with a thin layer of TiO2 on transparent, nanostructured transparent conducting oxides (TCO), with the outer TiO2 shell formed by atomic layer deposition. In this configuration, excitation and injection occur rapidly and efficiently with the injected electrons collected by the nanostructured TCO on the nanosecond timescale where they are collected by the planar conductive electrode and transmitted to the cathode for H2 production. This allows multiple oxidative equivalents to accumulate at a remote catalyst where water oxidation catalysis occurs
Effect of Covalent Functionalisation on Thermal Transport Across Graphene-Polymer Interfaces
This paper is concerned with the interfacial thermal resistance for polymer
composites reinforced by various covalently functionalised graphene. By using
molecular dynamics simulations, the obtained results show that the covalent
functionalisation in graphene plays a significant role in reducing the
graphene-paraffin interfacial thermal resistance. This reduction is dependent
on the coverage and type of functional groups. Among the various functional
groups, butyl is found to be the most effective in reducing the interfacial
thermal resistance, followed by methyl, phenyl and formyl. The other functional
groups under consideration such as carboxyl, hydroxyl and amines are found to
produce negligible reduction in the interfacial thermal resistance. For
multilayer graphene with a layer number up to four, the interfacial thermal
resistance is insensitive to the layer number. The effects of the different
functional groups and the layer number on the interfacial thermal resistance
are also elaborated using the vibrational density of states of the graphene and
the paraffin matrix. The present findings provide useful guidelines in the
application of functionalised graphene for practical thermal management.Comment: 8 figure
Metal Matrix–Metal Nanoparticle Composites with Tunable Melting Temperature and High Thermal Conductivity for Phase-Change Thermal Storage
All-optical control of a single plasmonic nanoantenna–ITO hybrid
We demonstrate experimentally picosecond all-optical control of a single plasmonic nanoantenna embedded in indium tin oxide (ITO). We identify a picosecond response of the antenna–ITO hybrid system, which is distinctly different from transient bleaching observed for gold antennas on a nonconducting SiO2 substrate. Our experimental results can be explained by the large free-carrier nonlinearity of ITO, which is enhanced by plasmon-induced hot-electron injection from the gold nanoantenna into the conductive oxide. The combination of tunable antenna–ITO hybrids with nanoscale plasmonic energy transfer mechanisms, as demonstrated here, opens a path for new ultrafast devices to produce nanoplasmonic switching and control.<br/
Vapor phase infiltration of zinc oxide into thin films of: Cis -polyisoprene rubber
Elastomers are an important class of polymers for many applications. Often, additives are added to the polymer matrix of elastomers to promote vulcanization or enhance physical or chemical properties. In this study, vapor phase infiltration (VPI) is investigated for transforming unvulcanized cis-polyisoprene (from natural rubber) into an organic/inorganic hybrid material. Specifically, we examine single-cycle infiltration with diethylzinc (DEZ) and water to form infiltrated zinc oxide species. Interestingly, low-temperature pre-heating of the cis-polyisoprene acutely affects the processes of infiltration, including diffusivity, maximum solubility, and chemical reactivity. We attribute these effects to a combination of film relaxation and oxidation. Independent of thermal pre-treatments, all infiltration processes exhibited consistent zinc oxide loading irrespective of purge time between the DEZ and water doses, indicating the presence of a strongly bound intermediate state between the DEZ precursor and the cis-polyisoprene polymer. Increasing infiltration process temperature accelerates diffusion and lowers the maximum solubility, in accordance with Fick's law and gas phase sorption equilibrium. Resulting organic-inorganic hybrid films show enhanced resistance to dissolution in toluene, a good solvent for the pure polymer
Thin, crystalline MgO on hexagonal 6H-SiC(0001) by molecular beam epitaxy for functional oxide integration
Improved epitaxy of barium titanate by molecular beam epitaxy through a single crystalline magnesium oxide template for integration on hexagonal silicon carbide
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