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.

Transition Metal‐Based Catalysts for Urea Oxidation Reaction (UOR): Catalyst Design Strategies, Applications, and Future Perspectives

“…The degrees of aggregation or dissolution of catalytic materials during the electrochemical process affect the electrochemical stability of the electrocatalysts. To minimize aggregation and further improve the activity of catalytic materials, materials with high specific surface area and high conductivity such as graphene, [130][131][132][133] activated carbon, [59] carbon nanotubes, [49,54,[61][62] carbon cloth, [48,[50][51]134] nickel foam, [40] Ti mesh, [135] and other support materials were hybridized with transition metal catalytic materials to anchor catalysts, which can in- crease the exposed specific surface area and accelerate the charge transfer (Figure 16). Owing to the high specific surface area, the active sites are highly dispersed, increasing the catalyst's electrical conductivity thereby accelerating the catalytic reaction kinetics.…”

“…This is achieved by supporting the catalyst on a substrate material with high conductivity and a large specific surface area. [26,31,34,36,[47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] By facilitating better interaction with the electrolyte, the catalyst's performance is enhanced, leading to more effective urea oxidation. Various control strategies have been explored to achieve these enhancements in catalytic activity.…”

Synthesis, Development and Characterization of Nanotubes

“…In this Special Issue, the research articles are focused on the following: Carbon nanotubes: when combined with Pd nanoparticles loaded onto Co 3 O 4 , they serve as a promising cathode catalyst for enhancing the electrocatalytic activity and oxygen reduction reaction at the cathode in direct urea fuel cells [1]; they decrease the incidence and severity of A. solani, and increase the fruit yield of tomato crop and dry shoot biomass [2]; they are used as electromechanical sensing devices when doped with resins [3]; they are used for the non-covalent functionalization and dispersion of two different S-layer proteins for the development of novel materials, such as biosensors [4]; when coupled with reduced graphene oxide (rGO) on a Si substrate, they lead to the formation of electrically conductive nanostructures for interconnections in nanoelectronics [5]; when properly dispersed in a liquid crystal matrix, they present dielectric properties considerably different from those of the pure liquid crystal [6].…”

Electrochemical Nucleation and Growth of Pd-Co Alloy Nanoparticles from the Reline Deep Eutectic Solvent

“…[14][15][16][17][18][19][20][21] Two central features are most valuable when obtaining MeNPs: first that they should be readily synthesized and second, that they should be endowed through diverse means with notable physicochemical properties; 22 these two have warranted the MeNPs entrance into the domain of a myriad applications. Notably, palladium-cobalt nanoparticles, PdCoNPs, have been used as catalytic materials within the Fuel Cells devices for the oxidation of ethanol, 23 methanol, 24 formic acid, 25 urea, 26 glycerol 27 and for oxygen reduction reaction, 28 performing better than PdNPs. For instance, PdCoNPs were electrodeposited onto glassy carbon electrode, GCE, from aqueous solutions containing polyvinylpyrrolidone, PVP, as NPs stabilizer and refrain their agglomeration, in Direct ethanol fuel Cells (DEFCs).…”