From Science Daily:
Fuel cells convert the chemical energy stored in hydrogen (H2) into electrical energy by electrochemically “combusting” hydrogen gas with oxygen (O2) from the air into water (H2O), thereby generating electricity. As a result, future electric automobiles might be operated quite well with fuel cells instead of with heavy batteries. But for “cold” combustion of hydrogen and oxygen to function well, the anode and cathode of the fuel cell must be coated with extremely active catalysts. The problem is that the platinum-based catalysts employed for this contribute about 25 per cent of the total fuel-cell costs.
However, iron-nitrogen complexes in graphene (known as Fe-N-C catalysts) have been achieving levels of activity comparable to Pt/C catalysts for several years already. “Systematic investigation of Fe-N-C catalysts was difficult though, since most approaches for preparing the materials lead to heterogeneous compounds. These contain various species of iron compounds such as iron carbides or nitrides besides the intended FeN4 centres,” explains Sebastian Fiechter of HZB.
High density of catalytically active centres
“We had already developed a new preparation method at HZB a few years ago to produce an inexpensive catalyst material from organometallic compounds such as iron or cobalt porphyrin,” reports Peter Bogdanoff, HZB. Ulrike Kramm and Iris Herrmann-Geppert improved the process for producing it as part of their doctoral studies at HZB. As a result, the metal-N-C catalysts developed at HZB held the world record for the highest density of catalytically active centres of various nitro-metallic compounds up to about 2011. However, it remained…