NiCo2O4/rGO hybrid nanostructures for efficient electrocatalytic oxygen evolution

Abstract

We report the synthesis of NiCo 2 O 4 /reduced graphene oxide (NiCo 2 O 4 /rGO) hybrid hierarchical structures with unique nanonet and microsphere morphologies by organic polar solvent-assisted solvothermal method. The electrocatalytic oxygen evolution reaction (OER) activity of these materials is studied by cyclic voltammetry, linear sweep voltammetry and chronoamperometry methods in O 2 -saturated 0.1 M KOH solution. The NiCo 2 O 4 /rGO hybrid nanocomposite materials are found to be highly active electrocatalysts for OER at lower overpotentials. The nanonet and microspherelike NiCo 2 O 4 /rGO catalysts require overpotentials of 0.450 and 0.530 V at a current density of 10 mA cm −2 , and their corresponding Tafel slopes are 53 and 62 mV dec −1 , which are much lower than values reported for non-precious electrocatalysts. Further, both NiCo 2 O 4 /rGO catalysts show good catalytic stability with current retention more than 92 % over long period of 15,000 s determined by chronoampirometry and at the end of 1000th cycle determined by linear sweep voltammetry. The enhanced OER activity of nanostructured NiCo 2 O 4 /rGO hybrid catalysts is attributed to synergistic interaction between rGO and NiCo 2 O 4 , which seems to be essential for maintaining the large contact area at the electrode-electrolyte interface, better mass, and charge transport and to minimize the aggregation of NiCo 2 O 4 nanoparticles.

Oxygen‐Vacancy and Surface Modulation of Ultrathin Nickel Cobaltite Nanosheets as a High‐Energy Cathode for Advanced Zn‐Ion Batteries

“…20–0781), although the peaks for P–NiCo 2 O 4‐ x sample were considerably less intense, which again indicates the markedly decreased crystallinity of NiCo 2 O 4 NSs after the phosphating treatment. Figure S6 in the Supporting Information depicts the Raman spectra of pristine NiCo 2 O 4 and P–NiCo 2 O 4‐ x samples, both of which contained three peaks at 470, 550, and 662 cm −1 , corresponding to the E g , F 2g , and A 1g models of spinel NiCo 2 O 4 . Compared with pristine NiCo 2 O 4 NSs, the Raman peak at 550 cm −1 for P–NiCo 2 O 4‐ x NSs was weaker and broader, and had shifted to a lower wave number due to the increased concentration of Ni 2+ at octahedral sites on the surface .…”

Electro-oxidation of a cobalt based steel in LiOH: a non-noble metal based electro-catalyst suitable for durable water-splitting in an acidic milieu

“…Currently, electrocatalysts, even when based on non-noble metals, are known to be efficient and durable toward OER at high pH values. 1,[14][15][16][17][18][19] However, alkaline electrolyzers are less resistant against fre-quently occurring changes of the current load. 1 Proton exchange membrane (PEM) electrolyzers not only benefit from higher gas purity and higher efficiency, but also are suitable for the storage of renewable energy which is basically charac-terized by high dynamics.…”

A comparative study of different electrodeposited NiCo2O4 microspheres anchored on a reduced graphene oxide platform: electrochemical sensor for anti-depressant drug venlafaxine

“…It has high electrochemical reactivity, good mechanical rigidity, low background current, low cost, commercial availability, offer simple polishing procedure easy in modication and it is considered user and environmental-friendly electrode. [32][33][34] Due to its remarkable electrochemical properties, bimetallic oxides such NiCo 2 O 4 have been used in different elds as electrocatalyst 35,36 and in drug delivery system. 37 They have tunable chemical and physical properties, low cost, low toxicity and natural availability.…”