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College of Science, Engineering and Technology

CSET Research Flagship 4: Fuel Cell & Nanotechnology

Flagship Project Leader: Prof Ayo Afolabi

Background:

Most of the energy needed for domestic and industrial consumption comes from only one natural source which is fossil fuel. This situation makes the world fossil fuel demand out-step the fossil fuel production and resulted in energy crisis due to shortage in supply and price instability. A significant outcome from the energy crisis was the realization that the earth’s fossil fuels are limited resources and they have been shrinking in recent years. There is also awareness that individuals and countries have real responsibilities not only for future generation of energy but to also conserve the environment because whatever is taken from the earth has an explicit cost to the geophysical state of the environment. Though there is no energy source that is completely environmentally safe, but energy must be used more wisely in order to minimize environmental hazard and optimize the efficiency with which it is produced.

Concerns for the environment and increasingly dependent on imported fossil fuels call for alternative source of energy and utilization of existing energy sources. Fuel cells, especially Proton Exchange Membrane Fuel Cell (PEMFC), which convert chemical energy directly to electrical energy, are considered promising and attractive replacement for existing sources of energy. It has a variety of applications in industries, transportation and small - scale power generation because of its low temperature of operation which allow for easy start up, quick response to change in load and operating condition as well as the easy of assembling by the industrial process.

Carbon is a critical material in the preparation of fuel cell electrodes and carbon nanotubes (CNTs) have been promising in this sort of applications. CNTs are bundle of layers of cylindrical graphite sheet with diameters ranging from 0.4 – 100nm and length ranging from several microns to millimetres. Based on their discovery, CNTs are classified into two groups namely: Single-Walled Carbon Nanotubes (SWNTs) and Multi-Walled Carbon Nanotubes (MWNTs).

Due to their nanometric size and interesting properties, they have received numerous theoretical and experimental studies and also of great interest for many applications not only in PEMFC but also in batteries, flat panel display, chemical sensor and transistor. Carbon nanotubes have become an active field of nanotechnology research particularly in terms of synthesis, characterization and applications. This is due to their unique structure and properties that make them suitable after modification for many industrial applications such as in biomedical, electrical, and electronic devices. Numerous studies have been devoted to the nature of the support due to its important role for high catalyst performance in heterogeneous catalytic reactions.

For fuel cells, electrical conductivity, porosity, surface area, morphology and corrosion resistance are of importance in selection of support materials. Based on these considerations, carbon black has usually been used in PEMFC. In recent years however, many novel synthetic carbons have been developed and studied as support materials for PEMFC. CNTs, owing to their unique mechanical and electronic properties, have attracted great interest as supports for electrocatalyts in PEMFC since their discovery and large scale synthesis.

Many authors prefer the use of CNTs to conventional carbon black as base material for catalyst electrode in PEMFC not only due to their combined outstanding properties such as electrical, electronic, adsorption, mechanical and thermal properties but carbon black has the tendency of trapping the platinum catalyst in deep cracks of its crystal boundaries which makes the catalyst unevenly distributed in it. The combination of advantageous properties of both platinum nanoparticles and CNTs is expected to produce improved performance and is therefore of interest for research and development of supported platinum catalysts.

Despite the high potential of PEMFC as an environmental friendly alternative energy source, high cost and limited durability hinder its production for commercial application. Progress has been made over the past few years on ways to achieve the commercialization of this alternative energy source by reducing the cost of the cell contents consisting of the electrode, the flow field plate and membrane. But the monopoly of the membrane synthesis by few nations and companies, and lack of locally available material to provide alternatives to imported membrane leads to heavy dependence on importation. This is coupled with high cost of platinum which forms the electrode materials.

It is therefore challenging and worthwhile to investigate the local production of MEA using locally and readily available materials in South Africa. MEA which is considered as the heart of PEM fuel cells is made up of the polymer electrolyte and electrodes. Polymer electrolyte is produced from polystyrene butadiene while electrodes are made of platinum. South Africa is currently the only African country that manufactures Polystyrene Butadiene Rubber and also a major exporter of platinum in the world. 

Achieving this aim will be an enormous contribution to knowledge in the development of CNTs in South Africa, conservation of foreign exchange and exploitation of our naturally occurring resources. This study would open more challenges on investigations and developments of carbon nanotechnology, fuel cell technology and other technological practices in the country for nation building.

Research aims:

  • Synthesize, characterize, and optimize the local production of membrane electrode assembly for fuel cell.
  • The results of this work are expected to give a technologically sound, environmentally friendly, and commercially viable process route for the fabrication of membrane electrode assembly for fuel cell that will be of benefit for domestic and industrial purposes in South Africa and the world at large.
  • The study will involve assessing and determination of experimental data for modelling, optimization and economic evaluation of the process.

Development/Capacity Building aims:

  • Increase research outputs by publishing in accredited journals and peer reviewed local and
    international conference proceedings.
  • Provide a forum for knowledge exchange and interaction in the areas of fuel cell and nanotechnology through seminar presentation by the members of the group and researchers in the field of fuel cell and nanotechnology from other institutions.
  • Supervise postgraduate students in the area of application of nanotechnology in fuel cell technology