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

Abstract

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.