Polymer electrolyte fuel cells (PEFCs) have wide variety of commercial applications, however due to poor durability and high cost, this technology has currently not reached its commercialization stage. Poor durability is mainly attributed to carbon support corrosion during start-up and shut-down of the fuel cell. Corrosion of the electrocatalyst support materials has numerous adverse effects on the performance of the fuel cell, such as weakening of metal-support interaction which results in Pt detachment, dissolution and sintering. Hence, the electrochemical active surface area is significantly reduced. It is clear that there is an urgent need for more robust, high performance alternative support materials to carbon. In this study, metal nitrides and borides (TiN, ZrN, TiB2, ZrB2 and LaB6) were evaluated as potential support materials, in an attempt to improve the durability and performance of PEFCs. Metal nitrides and borides were first subjected to a stability test by exposing them to potential cycling from 0.0 V vs SHE to 1.5 V vs SHE in 0.1 M HClO4, 3000 times at room temperature. It was found that metal nitrides were more electrochemically stable than metal borides. Metal nitrides were passivated by formation of surface oxides (oxynitrides and metal oxides), whilst metal borides formed a B2O3 layer which is less protective than metal oxides and oxynitrides. Thus metal borides were continuously oxidised over the 3000 cycles; however, the rate of oxidation was much lower compared to Vulcan XC-72 carbon. Using a wet chemical (impregnation) method well dispersed Pt nanoparticles, with a narrow size distribution could be deposited on all support materials except for Zr-based materials. The prepared catalysts were electrochemically characterised and it was found that Pt supported on metal nitrides and borides showed less Pt utilisation and activity towards ORR, compared to Pt/C. This was attributed to the presence of surface oxides, which significantly reduced electron conductivity. Pt/LaB6 showed reasonable activity, although it was still lower than of its counterpart Pt/C. The durability of Pt/LaB6 was evaluated by applying typical load cycling and start stop simulating protocols and it was found to be more durable than Pt/C. From a performance point of view, Pt supported on carbon is still the best but less durable than metal nitrides and borides. However, Pt/LaB6 shows great potential.

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