Hierarchical nanostructured NiCo2O4 as an efficient bifunctional non-precious metal catalyst for rechargeable zinc–air batteries

Abstract

A nickel-doped cobalt oxide spinel structure is a promising non-precious metal electrocatalyst for oxygen evolution and oxygen reduction in rechargeable metal-air batteries and water electrolyzers operating with alkaline electrolytes. One dimensional NiCo2O4 (NCO) nanostructures were prepared by using a simple electrospinning technique with two different metal precursors (metal nitrate/PAN and metal acetylacetonate/PAN). The effect of precursor concentration on the morphologies was investigated. Single-phase, NCO with an average diameter of 100 nm, porous interconnected fibrous morphology was revealed by FESEM and FETEM analysis. The hierarchical nanostructured 1D-spinel NiCo2O4 materials showed a remarkable electrocatalytic activity towards oxygen reduction and evolution in an aqueous alkaline medium. The extraordinary bi-functional catalytic activity towards both ORR and OER was observed by the low over potential (0.84 V), which is better than that of noble metal catalysts [Pt/C (1.16 V), Ru/C (1.01 V) and Ir/C (0.92 V)], making them promising cathode materials for metal-air batteries. Furthermore, the rechargeable zinc-air battery with NCO-A1 as a bifunctional electrocatalyst displays high activity and stability during battery discharge, charge, and cycling processes.

Anchoring CoFe2O4 Nanoparticles on N‐Doped Carbon Nanofibers for High‐Performance Oxygen Evolution Reaction

“…It is well‐documented that the spinel‐type binary transition metal oxides (AB 2 O 4 , A, B = metal) represent a class of promising candidates for water oxidation catalysis because of their high abundance, low toxicity, rich redox chemistry, and superior stability 12, 13, 14, 15, 16, 17. However, their intrinsically inferior electrical conductivity during electrocatalysis process exerts remarkably negative impacts on their electrochemical performances.…”

“…Fortunately, electrospinning represents a feasible and effective synthetic technique to fabricate metal oxide/carbon‐based nanofibers with large surface area, small and uniform grain size, and high morphological uniformity. Moreover, the electrospinning technique is more appealing and promising for practical applications due to its ease of operation, environmentally benign, and large scale production capability 31, 32, 33…”

A highly-efficient oxygen evolution electrode based on defective nickel-iron layered double hydroxide

“…However, the low efficiency and sluggish kinetics of oxygen evolution reaction (OER) catalysts have restricted the large-scale production of hydrogen [4,5]. Precious metal catalysts (such as IrO 2 and RuO 2 ) have to be involved in the electrode [6][7][8][9] to lower the overpotential and facilitate the OER process, but the limited performance (e.g., an onset potential of 1.5 V) has still hindered their commercialization [10][11][12][13]. Instead, 3d-transition metals (Ni, Co, Fe, etc.)…”

Tunable Bifunctional Activity of MnxCo3−xO4 Nanocrystals Decorated on Carbon Nanotubes for Oxygen Electrocatalysis

“…However,f urthere fforts are needed to enhance their efficiency,r educe toxicity,a nd increase electronic conductivity.P art of the issues can be addressed by multicomponent metal oxidest hrough improved electron hopping and enriched metal-ion redoxc ouples. [21] Recently,m ore abundant and cost-effectivem anganese-based [22] or combined cobaltmanganese complexes [19,[23][24][25] have shown promise for electrocatalysis over other spinel oxides, such as NiCo 2 O 4 , [26][27][28] CoFe 2 O 4 , [29][30][31] and ZnCo 2 O 4 . [32] Recent studies reveal that the spinelM n x Co 3Àx O 4 is ap otential candidate, and the corresponding activities can be further tuned through its phase and composition.…”