Core-shell carbon-ceramic hybrid fibres by electrospinning and atomic layer deposition

The general requirements for PEM fuel cell catalyst support materials are high electronic conductivity, high specific surface area and high electrochemical and chemical stability. Current structures typically consist of Pt particles on carbon black support material, but the mass activity of these high surface area nanoparticulate catalysts as well as stability of carbon support is limited. In this study we prepare corrosion resistant and electrically conductive catalyst support structures utilizing electrospinning and ALD. New approach for automotive PEM fuel cell catalysts were being developed in project Catapult. In this new approach platinum was deposited as an extremely thin layer on corrosion resistant supports of various morphologies including fibrous structures. VTT's developed a core-shell carbon-ceramic sub-µm fibrous catalyst supports utilizing atomic layer deposition (ALD) method on carbonized electrospun sub-µm fibres. Protective Ti-Nb-oxide layer, also acting as wetting tie-layer for platinum deposition, was applied by ALD method, and when annealed, carbon-ceramic supports showed similar conductivity than carbon fibre sheets prior to ALD coating. Carbon fibres without oxide layer showed better stability than carbon black reference, and oxide layer improved the stability: Core-shell fibres with 100 or more cycles of protective oxide layer showed similar stability than oxide itself.