Effect of Co₃O₄ Nanoparticles on Improving Catalytic Behavior of Pd/Co₃O₄@MWCNT Composites for Cathodes in Direct...

Direct urea fuel cells (DUFCs) have recently drawn increased attention as sustainable power generation devices because of their considerable advantages. Nonetheless, the kinetics of the oxidation-reduction reaction, particularly the electrochemical oxidation and oxygen reduction reaction (ORR), in direct urea fuel cells are slow and hence considered to be inefficient. To overcome these disadvantages in DUFCs, Pd nanoparticles loaded onto Co₃O₄ supported by multi-walled carbon nanotubes (Pd/Co₃O₄@MWCNT) were employed as a promising cathode catalyst for enhancing the electrocatalytic activity and oxygen reduction reaction at the cathode in DUFCs. Co₃O₄@MWCNT and Pd/Co₃O₄@MWCNT were synthesized via a facile two-step hydrothermal process. A Pd/MWCNT catalyst was also prepared and evaluated to study the effect of Co₃O₄ on the performance of the Pd/Co₃O₄@MWCNT catalyst. A current density of 13.963 mA cm^-2 and a maximum power density of 2.792 mW cm^-2 at 20 °C were obtained. Pd/Co₃O₄@MWCNT is a prospectively effective cathode catalyst for DUFCs. The dilution of Pd with non-precious metal oxides in adequate amounts is economically conducive to highly practical catalysts with promising electrocatalytic activity in fuel cell applications.