Combustion synthesis and electrochemical characterisation of Pt–Ru–Ni anode electrocatalyst for PEMFC

The present work studies the synthesis by the combustion method of an anode catalyst for protonic exchange membrane fuel cell (PEMFC) employing two different fuels, that is, urea and sucrose. The unsupported pure solid solution Pt_0.6Ru_0.3Ni_0.1 was selected from a calculated and empirical ternary phase diagram, which was previously studied. Theoretically, this particular composition exhibited single-phase features without the presence of secondary phases as RuO₃ and NiO, regarding the oxygen partial pressure conditions generated during the combustion synthesis. In the X-ray diffraction (XRD) analysis of the nanoparticles synthesized by using two different fuels, a single-phase Pt_0.6Ru_0.3Ni_0.1 alloy was detected. However, the X-ray photoelectron spectroscopy (XPS) studies showed that the nanoparticles prepared could present an onion-shell structure, in the case of the sample synthesized with sucrose as fuel, the external layers are partially constituted by Ni hydroxides, which can exhibit an active role in the hydrogen oxidation reaction. The electrochemical behaviour of this unsupported catalyst was performed by preparing MEAs, which were evaluated using a I–V polarisation curve test. The results obtained indicated that the nanoparticles prepared by sucrose have better performance, 260 mW/cm², than those prepared using urea, 170 mW/cm². These results are discussed in relation with the hydrogen oxidation mechanism. The results obtained reveal combustion synthesis as an appropriate method for preparing PEMFC electrocatalysts, due to its versatility, simplicity and fastness.