Solid–Solid Separation Approach for Preparation of Carbon-Supported Cobalt Carbide Nanoparticle Catalysts for Oxygen Reduction

Abstract

Transition metal carbides have received significant attention for oxygen reduction reaction (ORR) applications primarily owing to their good conductivity. However, cobalt carbide based catalysts (CoC x ) are difficult to prepare, owing to the preferential formation of metallic cobalt and cobalt oxide instead. Also, cobalt carbide nanoparticles rapidly coarsen and undergo grain growth. This is a problem as it results in low current density and poor active site exposures. In this study, carbon-supported CoC x (C@CoC x ) is successfully synthesized using the solid–solid separation synthesis method. The limitations identified to be associated with cobalt carbide nanoparticle based electrocatalysts are overcome. Here, the synthetic approach ensures good distribution and protection of CoC x on in situ generated carbon nanotubes. This results in robust activities with an appreciable onset potential of ∼0.92 V, a half-wave potential of ∼0.8 V, and a durability of ∼100% (tested on ∼22 h continuous operation runs). In alkaline medium, C@CoC x compares favorably with commercial platinum dispersed on carbon (20 wt % Pt/C) and shows a higher current density of ∼300 μA/cm2 at an electrode potential of 0.6 V. All of these indicate that there is a synergistic charge transfer between CoC x and an in situ generated carbon nanotube. This is due to intimate contact that exists between the two phases; it is in fact responsible for superior methanol tolerance observed, making it a good candidate for direct methanol fuel cells.

Enhanced cathodic activity by tantalum inclusion at B-site of La0.6Sr0.4CO0.4Fe0.6O3 based on structural property tailored via camphor-assisted solid-state reaction

“…All the catalysts were synthesized by using the CSSR method, and the comparison was made with the traditional solid-state reaction process to unravel the benefits of the CSSR approach. The procedure for the material preparation was invoked according to our previous reports with some modifications [24,25]. The LSCF was prepared by using a stoichiometric mixing ratio of SrCO In a typical synthesis procedure, the precursors were thoroughly mixed and infiltrated into camphor as pore formers, and the mixing ratio (precursors to camphor) was kept at 2 : 1 to avoid carbothermal reaction and the formation of carbide phases.…”

“…It suggests a modification to the chemical environment of the elements present in the LSCF. This had a possibility of enhancing the electrochemical activity because the material with a low amount of segregated Sr-species has a tendency to reduce the formation of passivated Sr-O [25].…”

Carbon-Coupling Metallic Cobalt as Trifunctional Catalysis for Oxygen Reduction/Evolution and Hydrogen Evolution

“…[5] Rasaki's group reported Pt-comparable carbon-supported cobalt (C@CoCx) ORR catalyst. [10] Furthermore, Chen's group designed a complex CoCx-based compound with CoFe phosphide and carbon carrier, denoted as…”