Introduction - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 1

Introduction
Zhiqun Lin and Jun Wang
Increasing worldwide demand on energy and the limited amounts of nonrenewable
fossil fuels have stimulated intense research and development efforts on renewable
energy, in the areas of solar cells, energy storage, fuel cells, and water splitting, to
name a few. However, widespread applications of renewable energy have not been
very successful mainly due to the high cost of materials and underdeveloped
processing and fabrication techniques. When compared to their bulk counterparts,
nanomaterials possess well-defined nanostructures and exceptional physical and
chemical properties. They exhibit great potential for developing low-cost, high
performance renewable energy sources. For example, rational engineering on the
nanostructure of photoanodes in dye-sensitized solar cells (DSSCs) has led to
largely enhanced device performance; quantum dots that show multiple exciton
generation (MEG) capability may offer great promise in the fabrication of solar
cells with power conversion efficiency exceeding the Shockley-Queisser limit;
development of advanced synthetic methods for pyrite nanoparticles has led to
solution-based fabrication of low-cost, environmental friendly thin film solar cells;
investigation on the Indium tin oxide (ITO)-free transparent conductive films will
help realize the commercialization of flexible electronic devices; design and fab-
rication of nanostructured electrodes have provided the opportunity for developing
high performance, low-cost fuel cells, efficient water splitting, high density
hydrogen storage, high performance batteries, and supercapacitors; and the
development of nanoscale phase change materials (PCMs) has contributed to the
preparation of more efficient heat transfer fluids. Despite tremendous efforts on
incorporating nanomaterials into a variety of renewable energy sources, the high