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ZnO-Cu x O core-shell radial heterojunction nanowire arrays were fabricated by a straightforward approach which combine two simple, cost effective and large-scale preparation methods: (i) thermal oxidation in air of a zinc foil for obtaining ZnO nanowire arrays and (ii) radio frequency magnetron sputtering for covering the surface of the ZnO nanowires with a Cu x O thin film. The structural, compositional, morphological and optical properties of the high aspect ratio ZnO-Cu x O core-shell nanowire arrays were investigated. Individual ZnO-Cu x O core-shell nanowires were contacted with Pt electrodes by means of electron beam lithography technique, diode behaviour being demonstrated. Further it was found that these n-p radial heterojunction diodes based on single ZnO-Cu x O nanowires exhibit a change in the current under UV light illumination and therefore behaving as photodetectors.

Single ZnO nanowires prepared by wet and dry methods are used as channels in high performance back-gated field effect transistors working in low power operation mode, with on-off ratios up to 10 and mobilities up to 167 cm V s. The nanowires' properties, generated by the growth techniques, influence the parameters of the transistors, therefore a throughout comparison is made.

Palladium is one of the most efficient metals for the hydrogenation of organic compounds. However, when molecules, such as nitroaromatics, with several reducible functionalities, are hydrogenated, Pd, like any other very active metal, such as nickel or platinum, often behaves unselectively. One strategy to render Pd more selective is to choose the proper support. Herein, we show that MAX phase powders of Ti3SiC2, Ti2AlC, or Ti3AlC2 can chemoselectively hydrogenate 4-nitrostyrene to 4-aminostyrene, with 100% selectivity, at around 3–4% conversion. To boost the latter, we loaded Ti3SiC2 with 0.0005 wt % Pd and increased the conversion to 100% while maintaining the 4-AS selectivity at >90%. By optimizing the Pd loading, we were also able to increase the turnover frequency 100-fold relative to previous literature results. The identification of this highly efficient and chemoselective system has broad implications for the design of cost-effective, earth-abundant, nontoxic, metal catalysts, with ultralow noble metal loadings.

CuO–ZnO core–shell radial heterojunction nanowire arrays were obtained by a simple route which implies two cost-effective methods: thermal oxidation in air for preparing CuO nanowire arrays, acting as a p-type core and RF magnetron sputtering for coating the surface of the CuO nanowires with a ZnO thin film, acting as a n-type shell. The morphological, structural, optical and compositional properties of the CuO–ZnO core–shell nanowire arrays were investigated. In order to analyse the electrical and photoelectrical properties of the metal oxide nanowires, single CuO and CuO–ZnO core–shell nanowires were contacted by employing electron beam lithography (EBL) and focused ion beam induced deposition (FIBID). The photoelectrical properties emphasize that the p–n radial heterojunction diodes based on single CuO–ZnO core–shell nanowires behave as photodetectors, evidencing a time-depending photoresponse under illumination at 520 nm and 405 nm wavelengths. The performance of the photodetector device was evaluated by assessing its key parameters: responsivity, external quantum efficiency and detectivity. The results highlighted that the obtained CuO–ZnO core–shell nanowires are emerging as potential building blocks for a next generation of photodetector devices.