Introduction - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 5

reviewed, which should help to realize commercially feasible OPV devices. In the
first section of this chapter, various nanomaterials showing the possibility to
substitute ITO are discussed, including metal nanogrids, metal nanowires, carbon
nanotubes, and graphene; followed by a discussion on the very recent progress in
the scale-up experiments on ITO-free OPVs modules.
Solution-based processing methods have been recognized as the most appro-
priate techniques for the fabrication of polymer-based electronic devices such as
OPVs and OLEDs. However, technical challenges, including large-area processing
technologies, coating quality, and long-term stability toward scalable and low-cost
polymer electronics, still remain. In a chapter by Guo et al., recent advances in
low-cost fabrication of OPVs and OLEDs are reviewed. Various scalable pro-
cessing methods are presented by focusing on the coating quality and the resulting
device performance in polymer-based electronics. This can ultimately lead to
conclusions on how appropriate coating techniques can be selected based on the
thickness requirement of each functional layer in polymer electronics. In the last
section of this chapter, ITO-free electrodes based on polymer materials are
introduced by evaluating their mechanical and optical properties, and a hybrid
ITO-free transparent conductive film based on metal mesh and conjugated poly-
mers is also introduced for the fabrication of large-area devices.
4 Hydrogen Energy and Fuel Cells
Hydrogen represents a clean and high gravimetric energy density fuel that could
potentially replace fossil fuels in many applications. However, the widespread
adoption of hydrogen fuels is stymied by a lack of efficient hydrogen generation and
high density hydrogen storage methods. Current technology for hydrogen genera-
tion is based on the stream methane reforming and water-gas shift reaction which
still relies on fossil fuels. Obviously, it is important to develop efficient, low-cost,
and scalable techniques to generate hydrogen in a sustainable manner. In this
context, photoelectrochemical water splitting has been considered as one of the
most promising approaches as presented thoroughly in the chapter by Li et al. The
most recent achievement in this area is comprehensively reviewed in this chapter,
and the key factor for efficient photoelectrochemical water splitting has been
identified to be the development of low-cost and efficient nanostructured photo-
electrodes. In another chapter by Prieto et al. on the development of hydrogen
storage materials, nanostructured magnesium and doped magnesium are described.
This includes the size and shape controllable synthesis of these nanostructures, the
kinetics of efficient hydrogen storage based on experimental observation and
modeling, and the theoretical models that could guide experimental efforts.
Fuel cells that convert the chemical energy stored in fuels into electricity through
electrochemical reactions with oxygen or other oxidizing agents have been
receiving considerable attention in the past few decades. However, the widespread
commercialization of fuel cells is still challenging due in part to the low catalytic