Nanostructured Materials for Electrochemical Energy Production and Storage

Photovoltaic cells have been dominated so far by solid state p-n junction devices made from silicon or gallium arsenide wavers or thin film embodiments based on amorphous silicon, CdTe and copper indium gallium diselenide (CIGS) profiting from the experience and material availability of the semiconductor industry. Recently there has been a surge of interest for devices that are based on nanoscale inorganic or organic semiconductors commonly referred to as “bulk” junctions due to their interconnected three-dimensional structure. The present chapter describes the state of the art of the academic and industrial development of nanostructured solar cells, with emphasis in the development of the dye-sensitized nanocristalline solar cell.

A short review is presented on the properties and main features of nanoscale materials, emphasizing the dependence of key properties on size for energy purposes. A general description is also given about nanoparticle synthesization methods (mainly oxides), focusing on advances in tailoring controlled shape nano-structures.

This chapter deals with the development of new methods for the design of more efficient electrochemical cells destined specifically for energy conversion and storage based on synthesis and design of functional electrodes and electrolytes. The main focus of this chapter is on novel strategies that exploit nanoscale architectures to enhance the efficiency of alternative energy conversion and storage devices as well as on the basic principles of electrochemistry governing the effects of nanoscale design on electrodes and electrolytes. In addition, the chapter provides a review of fundamental electron transfer concepts of relevance to electrochemistry in general and alternative energy devices in particular.

There are noteworthy developments in nanotechnology and its relevance to the energy field. Fuel cells especially benefit from electrodes and membrane electrolytes with nanostructured and therefore enlarged surfaces. Fuel cells also derive benefits from the development of nanoparticles and nanotubes for catalytic application, allowing also study of the molecular electrochemical behaviour. In this chapter we describe the impact of nanotechnology in the performance of the different components of the fuel cell as well as the impact of nanotechnology in the electrochemistry process.

Aerogels constitute a unique class of nanostructured materials. They possess a three-dimensional network of nanometer-sized solid particles within a continuous mesoporous volume. The materials have low density and high surface area and only recently have they begun to be explored as electrochemically active materials. This chapter reviews the importance of aerogel nanoarchitecture in achieving high-performance electrochemical properties. Results obtained with vanadium oxide aerogels are highlighted as these materials exhibit a number of desirable characteristics for secondary lithium batteries.

Hybrid metal/metal oxide—poly-para-xylylene (PPX) nanocomposites have attracted great interest, because of a broad spectrum of applications. A simple, low-cost preparation technique has been developed and comprises a cold-wall vacuum co-deposition technique. This co-deposition technique has been applied to synthesize nanocomposites, containing PPX and nanoparticles of Al, Sn, Zn, Ti and their oxides. Important is the oxidation kinetics of the metal clusters to their oxides in relation to the percolation threshold. The structure, microstructure, and properties of these composite materials have been studied by X-Ray diffraction, AFM, TEM, and electrical measurements. Anticipated applications of the present composites are photanodes for hydrogen production, active lithium-ion rechargeable battery materials, and chemical gas sensors. An important aspect of these composite materials is the nature of the interfacial properties of the nanostructured particles and the PPX material. The properties of selected composites will be discussed with focus on the nanos-tructured TiO₂/PPX composites as an anode material for a rechargeable lithium-ion battery.