Electro-deposition of Pd on Carbon paper and Ni foam via surface limited redox-replacement reaction for oxygen reduction reaction: Presentation

Abstract

Fuel cells continue to be investigated as alternative energy source because of the high energy demand worldwide. The electrocatalytic reduction of oxygen is of great importance in fuel cells and sensors. Noble metals have proved to be the best electrocatalysts for the oxygen reduction reaction (ORR). Among these electrocatalysts, Pd has attracted enormous attention since it is more abundant and cheaper than Pt. In the pursuit to improve reproducibility while overcoming the loss of catalytic activity during the catalyst preparation process, Pd nanosturctures are grown directly on fuel cell gas diffusion layers and evaluated for the ORR. Pd nanostructures were synthesized via surface-limited redox replacement (SLRR) reaction employing the electrochemical atomic layer deposition technique. Pd was deposited on carbon paper and Ni foam substrates using Cu as a sacrificial metal following the procedure published by Mkwizu et al. The electrochemical activity of the prepared nanostructures towards ORR was investigated in both acidic and alkaline electrolytes at various flow rates. The morphology and particle size of the deposited nanostructures were characterised using microscopy techniques such as scanning electron microscopy (SEM) and atomic force microscopy (AFM). The nanoparticle composition on the substrate was estimated using energy dispersive X-ray spectroscopy (EDX).