• Energy Research

The use of micro- and nano-sensors is nowadays becoming more important in order to monitor several aspects of human life and environment. Controlled production of metal oxides nanostructures for gas-sensing applications is therefore crucial to integrate nanosensors to most systems, as they are ideal materials for such utilization. Here, nickel oxide (NiO) polycrystalline nanowires were grown and used to realize sensors that can selectively detect hydrogen and ethanol gas. NiO semiconducting nanowires with polycrystalline structure were grown through an easy, cheap and scalable hydrothermal procedure. Morphology and crystal structure of the NiO nanowires were investigated by energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The NiO nanostructures were then tested as gas sensors showing very good performance in terms of sensor response (107% for hydrogen, 136% for ethanol), stability, response and recovery times (20 s for hydrogen, 35 for ethanol). Their tunable dual-selectivity to hydrogen and ethanol make them ideal for use in ethanol steam-reforming systems.(C) 2016 Elsevier B.V. All rights reserved.

The growth of nanohybrids synthesized by supersonic beam codeposition of metal oxide clusters, produced by microplasma cluster source, and of aerodynamically accelerated molecules has been explored as a novel approach to the preparation of controlled dye sensitized materials for photovoltaic applications. The hybrid nanostructures are formed through deposition via supersonic expansion processes, controlling the kinetic energy of the precursors. With this approach, we developed prototype dye sensitized solar cells based on nanostructured TiO2 and CuPc with different architectures. To explore the viability of this approach, we compare cells made layer by layer with those where an intermediate codeposited layer is inserted between the two raw materials. This latter type of cells presents an enhancement of the photocurrent of a factor of 45 and of the efficiency of a factor of 40. This work opens a new viable perspective in the growth and in the control of the interfacial properties of nanohybrid materials, by direct codeposition of molecules and oxide nanostructures, with demonstrated useful applications in photovoltaic devices.