Nanoscale Phenomena for Energy Conversion: Implication of Physical Parameters

(written by: Willy Yanto Wijaya)

 

Fifty years ago, Richard Feynman, a notable physicist, gave a talk in Caltech upon “There’s Plenty of Room at the Bottom”, describing an embryonic idea about nanoscale phenomena and its potential future application. He foresaw that the ability to manipulate individual atoms and molecules might be developed, which will bring interesting implications, since scaling down of a structure will make certain physical properties become more pronounced. On the other hand, some physical parameters will become less significant.

Several decades have passed, and many amazing phenomena in the nanoscale realm have been observed. To mention some: when reduced to the nanoscale, materials such as silicon could change from insulator become conductor; gold which is chemically inert at normal scale could turn into chemical catalyst at nanoscale; aluminum particles could become combustible at nanoscale.

Then, an exciting question is that how come these materials’ properties could change just by the scaling down? Scientists and engineers have been trying to seek the answer for these phenomena. One of the plausible explanations is that when undergoing scaling down (particularly to the nanoscale realm), magnitude of various physical parameters will also change. Gravity would become less important, surface area/volume would increase significantly (which might affect the surface tension); Van der Waals attraction would also become more important. The changing of these physical parameters (which could be termed as “statistical-quantum mechanical effects” + “surface phenomena at nanoscale”) will then influence/ alter the properties of the materials (such as mechanical, thermal, electronic, optical, and even catalytic properties).

Then, for the energy conversion applications, what kind of implications these phenomena might bring? Well, there’s a bunch of possible implications, ranging in various different fields of energy applications. One to mention is the application of these nanoscale phenomena in the chemical catalytic reactions.

As we know, most of energy conversion processes, such as hydrogen production from hydrocarbons, or reactions at fuel cell electrode, rely heavily on catalysts. It is estimated that 90% of all commercially produced chemical products involve catalysts at some stage in their manufacturing processes. Regarding these enormous applications, potentials of applying the nanoscale phenomena into the catalytic reactions are tantalizing.

We know that in chemistry, reactivity is governed by several parameters such as specific surface area, temperature, pressure, and even existence of contaminants. In microscopic view, reactivity is regarded as being governed by the sub-atomic properties of the compound (such as the structure, bonding, and compositions of the compounds). Therefore, if we can understand how these nanoscale parameters interact one another in the catalytic processes of energy conversion, we might have a clue how to design better catalysts and achieve more efficient conversion. In addition, by the rapid development of nanofabrication technology nowadays, catalyst might be tailored to a specific condition that suits our desired criteria for the optimization of the energy conversion reactions.

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