Professor Enn Lust, University of Tartu
PhD Jaak Nerut, University of Tartu
Professor Pawel J. Kulesza, University of Warsaw, Poland
Alternative energy conversion systems are novel solution for the energy and environmental crisis due to the limited resources of fossil fuels and the globally increasing pollution level. Many countries have invested into development of the environmental friendly renewable-and hydrogen energy technology. Polymer electrolyte membrane fuel cell (PEMFC) is a promising alternative energy conversion system, which has very high electrical efficiency because the energy of the chemical reaction is directly converted into electrical energy. The overall efficiency can be increased even further if the generated heat is used as well.
The electrochemical reactions occur on the surface of the catalyst, which usually is platinum nanoparticles supported onto the porous carbon. To minimize the use of platinum in the catalyst layer and through that the cost of a fuel cell, it is important to design a catalyst structure, which has small Pt-nanoparticles with large effective surface area finely dispersed at the porous surface of the catalyst support.
This is the first systematic study where the molybdenum carbide derived carbons (C(Mo2C)) with tuneable porosity have been studied as a catalyst support for the oxygen electroreduction (ORR). For this work the C(Mo2C)s were prepared from Mo2C at six different fixed chlorination temperatures from 600 °C to 1000 °C and the ORR kinetics was studied on different pristine C(Mo2C) and Pt nanoclusters activated composite Pt-C(Mo2C) and Pt Ru alloy nanoclusters activated Pt-Ru-C(Mo2C) electrode materials in 0.5 M H2SO4 solution at 22 ± 1°C.
It was demonstrated that ORR at micromesoporous carbons strongly depends on the C(Mo2C) synthesis temperature, i.e. on the porosity, pore size distribution, ratio of micropore and mesopore surface area and volume, crystallinity and amount of catalytically active defected areas, expressed at the C(Mo2C) surface.