Mesoporous NiCo₂O₄ Nanoplates on Three-Dimensional Graphene Foam as an Efficient Electrocatalyst for the Oxygen Reduction Reaction

Abstract

Catalysts for the oxygen reduction reaction (ORR) are highly important in fuel cells and metal-air batteries. Cheap ORR catalysts with ultrahigh electrochemical activity, selectivity, and stability are extremely desirable but still remain challenging. Herein, mesoporous NiCoO nanoplate (NP) arrays on three-dimensional (3D) graphene foam are shown to be a highly economical ORR catalyst. This mesoporous mixed-valence oxide can provide more electrocatalytic active sites with increased accessible surface area. In addition, graphene-foam-supported NiCoO NP arrays have a 3D hierarchical porous structure, which is of great benefit to ion diffusion and electron transfer. As a result, the mesoporous NiCoO NP arrays/graphene foam catalyst exhibits outstanding ORR performance with the four-electron reduction of O to HO in alkaline media. Furthermore, the mesoporous catalyst shows enhanced electrocatalytic activity with a half-wave potential of 0.86 V vs RHE and better stability compared with a commercial Pt/C catalyst.

IrNi nanoparticle-decorated flower-shaped NiCo2O4 nanostructures: controllable synthesis and enhanced electrochemical activity for oxygen evolution reaction

“…3a, the larger magnification image of IrNi/NiCo2O4 provides data for the lattice fringe. The lattice spacing of 2.43 Å, 2.83 Å and 4.37 Å correspond to the lower index (111), (220), (311) crystal planes of NiCo2O4, respectively [32]. Interestingly, another two types of lattice fringes are found in the HRTEM images, and we have assigned them to IrNi nanoparticles.…”

Design and Application of Foams for Electrocatalysis

“…Considering the advantages of 3 D foams compared with 2 D substrates, the use of 3 D foams supported transition metal oxides directly as efficient ORR catalysts is thereby attractive. Guo and co‐workers designed a hydrothermal deposition method to grow NiCo 2 O 4 nanoplate array on the skeleton of a Ni foam‐template assisted CVD graphene foam (Figure ) . After modification on the surface of glassy carbon electrode (GCE), the NiCo 2 O 4 /graphene foam shows better ORR catalytic activity and higher tolerance to methanol than commercial Pt/C catalyst.…”

Controllable Synthesis of Ultrathin NiCo2O4 Nanosheets Incorporated onto Composite Nanotubes for Efficient Oxygen Reduction

“…Another approach is to rationally design porous nanostructures or ultrathin nanoparticles that can provide more electrochemical active sites and short ion/electron transport paths to facilitate an efficient ORR process. Guo and co‐workers reported the successful preparation of mesoporous NiCo 2 O 4 nanoplate arrays on 3D graphene foam . By virtue of the fully exposed NiCo 2 O 4 active edges and increased accessible surface area, this hierarchical nanomaterial manifested outstanding ORR performance with the four‐electron process in alkaline media.…”