In situ growth of spinel CoFe₂O₄ nanoparticles on rod-like ordered mesoporous carbon for bifunctional electrocatalysis of both oxygen reduction and oxygen evolution

Abstract

The lack of efficient electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has been a fatal issue for the development of metal-air batteries in large-scale commercialization. In this paper, spinel CoFe 2 O 4 (CFO) nanoparticles were successfully in situ grown onto rod-like ordered mesoporous carbon (RC) by a facile, scalable hydrothermal method, followed by annealing at different temperatures. The as-acquired CFO/RC nanohybrid pyrolyzed at 400 C (CFO/RC-400) has a high specific surface area (150.3 m 2 g À1 ) and two sets of uniform mesopore systems (3.38 and 19.1 nm), all of which are favorable for the improvement of the electrocatalytic activity. The hybridization of CFO nanoparticles and the RC matrix results in increased ORR and OER electrocatalytic activity of the CFO/ RC nanohybrids, which is significantly superior to that of unsupported CFO nanoparticles and pure RC.CFO/RC-400 shows better catalytic activity for the ORR with a direct four-electron reaction pathway than those prepared at other temperatures in terms of the onset potential and limiting current density.Furthermore, the CFO/RC-400 nanohybrid exhibits outstanding durability for both the ORR and OER, and can outperform commercial Pt/C. The excellent bifunctional electrocatalytic activities of the CFO/ RC nanohybrids are mainly owing to the hierarchical mesoporous structures of the nanohybrids and strong coupling between the CFO nanoparticles and the RC matrix.

A Review of Carbon-Composited Materials as Air-Electrode Bifunctional Electrocatalysts for Metal–Air Batteries

“…have gained much attention because of their low costs, considerable activities, high abundance (stability), and environmental friendliness [136][137][138]. To achieve better catalytic activities toward ORR and OER, however, net spinel oxides are usually attached onto conducting carbon substrates with the aim of assuring fast electron transport and good interaction between oxides and carbon [136].…”

“…To achieve better catalytic activities toward ORR and OER, however, net spinel oxides are usually attached onto conducting carbon substrates with the aim of assuring fast electron transport and good interaction between oxides and carbon [136]. For example, Li et al [137] performed an in situ growth of spinel CoFe 2 O 4 nanoparticles on rod-like ordered mesoporous carbon (CFO/RC) through a hydrothermal treatment process with an annealing procedure in which Co(NO 3 ) 2 ·6H 2 O and Fe(NO 3 )·9H 2 O were used as Co and Fe sources. According to different annealing temperatures of 300, 400, 500, and 600 °C, the final composites were labeled as CFO/RC-300, CFO/RC-400, CFO/RC-500, and CFO/RC-600, respectively.…”

Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

“…For comparison, the ORR properties of CoHCS-900 and NHCS-900 were also evaluated to obtain the effect of N and Co individually. Figure S4a shows To evaluate the catalytic performance, all samples were examined by using a three-electrode system in an O2 or a N2-saturated 0.1 M KOH solution [51]. The electrocatalytic ORR performances of CoNHCSs were measured using the rotating disk electrode (RDE) method after activation by cyclic voltammograms.…”

NiCo2O4/rGO hybrid nanostructures for efficient electrocatalytic oxygen evolution

“…Hybridizing oxide nanomaterials with conductive support like activated carbon and Vulcan carbon can significantly enhance the conductivity and specific surface area of the oxide catalyst and thus improve the overall catalytic activity as well as stability. Moreover, carbon also promotes the chemisorption of hydrogen and oxygen on oxide materials [36,37], which is an advantageous feature. However, the drawback is that carbon materials easily undergo oxidative corrosion under OER mode.…”