Abstract
The hydrogen oxidation (HOR) and evolution reactions (HER) under alkaline conditions are sluggish when compared to activity at low pHs. The consequence is that when catalysts are employed in anion exchange membrane fuel cells and water electrolysers, high loadings of precious metals are required to achieve the necessary performance. Strong metal-support interactions can be exploited to enhance the activity and stability of metal nanoparticles. This usually occurs through strong electronic coupling. Here, a series of transition metal nanoparticle electrocatalysts (Pd, Ir, Ru and Rh) with a metal loading of 10 wt%, were prepared using two supports; carbon and carbon-CeO2 (50:50). Each material is characterized using XRD, XPS, TEM and electrochemical tests, EIS and tafel analysis is performed in order to understand the HER and HOR activities. The presence of CeO2 enhances the activity of Pd, Ir and Rh. Ruthenium has superior activity in term of mass activity, specific activity and i0, both for HER and HOR. The HOR/HER exchange current (i0) of Ru/C has an average value of 106 A gMetal−1. Importantly, EIS and capacitance measurements show that CeO2 promotes catalyst utilization and lowers ionic resistance.
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