Materials that can produce electricity are at the core of piezoelectric research and the vision of self-powering machines and devices. With the emergence of nanotechnology and the use of nanomaterials, the field of piezoelectrics and nanopiezotronics has experienced a lot of new and interesting research efforts. A recent study, for instance, has demonstrated that the small vibrational energy waste generated in the environment from noise, wind power, running water, or water wave action can be scavenged or harvested as a driving force for direct water splitting. The researchers propose a new piezoelectrochemical mechanism for the direct conversion of mechanical energy to chemical energy and subsequently the splitting of water into hydrogen and oxygen.
Artificial photosynthesis can offer a clean and portable source of energy supply as durable as the sunlight. Using sunlight to split water molecules and form hydrogen fuel is one of the most promising tactics for kicking our carbon habit. Of the possible methods, nature provides the blueprint for converting solar energy in the form of chemical fuels. A natural leaf is a synergy of the elaborated structures and functional components to produce a highly complex machinery for photosynthesis in which light harvesting, photoinduced charge separation, and catalysis modules combined to capture solar energy and split water into oxygen and hydrogen efficiently. Chinese researchers have now demonstrated the design of an efficient, cost-effective artificial system to mimic photosynthesis by copying the elaborate architectures of green leaves, replacing the natural photosynthetic pigments with man-made catalysts and thereby realizing water splitting- a major advance in energy conversion.
Nanotechnology catalytical techniques are having a profound impact on clean energy research and development, ranging from hydrogen and liquid fuel production to clean combustion technologies. In this area, catalyst stability is paramount for technical application, and remains a major challenge, even for many conventional catalysts. Thermal stability in particular is a challenge across many currently discussed technical applications and an obstacle for many nanocatalyst-enabled devices, from sensors to fuel production. In particular fuel processing technologies (hydrogen and/or liquid fuel production from fossil and renewable resources, clean combustion) typically proceed at particularly severe conditions (high temperatures, high through-put, contaminated fuel streams, etc) and hence require particular attention to catalyst stabilization, but even many processes at much lower temperature conditions, such as fuel cells, are still looking for catalysts with improved stability.
Due to their unique structural and electrical properties, carbon nanotubes have been extensively investigated as promising catalyst supports to improve the efficiency of direct ethanol/methanol fuel cells. CNTs have a significantly higher electronic conductivity and an extremely higher specific surface area in comparison with the most widely-used Vulcan XC-72R carbon support. Several approaches, such as electrochemical reduction, electroless deposition, spontaneous reduction, sonochemical technique, microwave-heated polyol process, and nanoparticle decoration on chemically oxidized nanotube sidewalls, have been reported to form CNT-supported platinum catalysts. Some remarkable progress has been made in synthesis techniques; however, pioneering breakthroughs have not been made yet in terms of cost-effectiveness catalyst activity, durability, and chemical-electrochemical stability. Nanotechnology researchers in the U.S. have now discovered that platinum nanoparticles selectively grow on carbon nanotubes in accordance with single-stranded DNA locations.
The batteries that power our everyday devices, from laptop computers, to mobile phones, watches, toys and flashlights, are a major source of pollution. The average household in the Western world uses about 20 batteries a year, resulting in hundreds of thousands of tons of discarded batteries that end up in landfills. When the battery casing corrodes, toxic heavy metals like mercury and cadmium can leak out and pollute soil and ground water. Researchers have been working on non-metal batteries but so far the performance of the used materials has not been good enough for commercial applications. One way to improve the performance of nonmetal-based energy storage devices is to use composite electrode materials of conductive polymers, deposited as thin layers on a suitable large surface area substrate. Researchers have now developed a novel polypyrrole-cellulose composite electrode material that is mechanically robust, lightweight, and flexible.
In today's Spotlight we take a look at a specific example of the challenges researchers face in improving fuel cell technology and the important role that modern laboratory instruments such as electron microscopes play in their work. Fuel cells have gained a lot of attention because they provide a potential solution to our addiction to fossil fuels. Energy production from oil, coal and gas is an extremely polluting, not to mention wasteful, process that consists of heat extraction from fuel by burning it, conversion of that heat to mechanical energy, and transformation of that mechanical energy into electrical energy. In contrast, fuel cells are electrochemical devices that convert a fuel's chemical energy directly to electrical energy with high efficiency and without combustion (although fuel cells operate similar to batteries, an important difference is that batteries store energy, while fuel cells can produce electricity continuously as long as fuel and air are supplied).
The field of printable electronics is already well established. The biggest limitation to further increasing the functionality of printed electronics devices is energy management, i.e. the space requirement and cost of batteries. Ideally, power and energy storage devices will be integrated into the manufacturing process to be printed at the same time. What is still needed to complement a further deveopment of printed electronics device technology are truly printable charge storage devices that can be easily fabricated using large-scale, solution-based, roll-to-roll processing, while still displaying good electrochemical performance. Only fully printable charge storage devices would allow for full integration into the manufacturing process of printed electronics.
New work by this Canadian research team has now demonstrated that it is possible to significantly increase the catalytic site density of iron-based non-precious metal catalysts (NPMCs) to levels that were not thought possible before. The problem that this work resolves is that of the low activity of NPMCs compared to platinum-based catalysts. The best of these new NPMCs is more than 30 times more active compared to the previous best reported activity for NPMCs, and about 100 times more active than the majority of other NPMCs. Furthermore, their activity has reached about 1/10th the volumetric activity of state-of-the-art platinum-based catalysts (about 50 wt% platinum on carbon), which is the 2010 NPMC activity target set by the U.S. Department of Energy.