Electrode Material For Oxygen Evolution Reaction Research Articles

Designing a bimetallic transition metal oxide/hydroxide composite for effective electrocatalytic oxygen evolution reaction

The oxygen evolution reaction (OER), owing to its sluggish nature, demands efficient and stable catalysts with low production cost, during the electrocatalytic water splitting. In this respect, a series of bimetallic ZnO-Ni(OH)2 composite materials were prepared as electrode materials for OER. The synthetic procedure followed the polyvinylpyrrolidone (PVP) and dopamine (DA) assisted hydrothermal process. The growth modification ability of PVP and adhesive property of polydopamine (from DA) were utilized to attain the 3D interconnected structures. The precursor concentrations were varied to obtain most efficient catalyst, ZNDP-1. In alkaline medium, ZNDP-1 showed a low over potential of 170 mV (@10 mAcm−2 current density) and a Tafel slope of 61 mV dec−1 with significant stability. The surface defects, porosity and synergism within metal centers might cause efficient electrocatalytic activity. Furthermore, DFT studies were performed to understand the mechanistic pathway.

Boosting oxygen evolution reaction performance by nickel substituted cobalt-iron oxide nanoparticles embedded over reduced graphene oxide

Designing non-precious-metal (NPM) electrocatalysts for oxygen evolution reaction (OER) from alkaline water is of paramount importance for clean, sustainable and conversion technologies. Herein, we report a facile, scalable and rapid microwave assisted synthesis to produce Ni substituted cobalt-iron oxides Co1-xNixFe2O4 (x = 0, 0.10, 0.25, 0.50, 0.75 and 1) supported over conductive reduced graphene oxide (rGO) and successfully employing them as electrode materials for OER in alkaline medium. Interestingly, by tuning Ni amount in cobalt-iron oxide has a profound influence on the OER activity i.e., Co0.75Ni0.25Fe2O4/rGO exhibits the best OER performance with an overpotential of 440 mV at 10 mA cm−2 and considerable electrochemical stability over 1000 cycles and even up to 10 h in 0.1 M KOH solution.

Synergic effects enhance the catalytic properties of alpha-Ni(OH)2-FeOCPc@rGO composite for oxygen evolution reaction

The effect of size and degree of crystallinity, and the synergic interaction of α-Ni(OH)2 nanoparticles (α-Ni) with reduced graphene oxide (rGO) and octacarboxyphthalocyaninate iron(II) (FeOCPc), on the electrocatalytic activity for the oxygen evolution reaction (OER) are demonstrated using structurally well-defined nanocomposite materials. Larger and crystalline α-Ni@rGO-K nanoparticles (4.7 ± 1.8 nm) generated materials with higher activity than the respective α-Ni(OH)2Na derivatives (1.8 ± 0.3 nm), where the incorporation of rGO improved dramatically the performance. However, an even larger efficiency was achieved when α-Ni@rGO-K was covered up with a controlled amount of FeOCPc, a poor molecular OER catalyst, in this way demonstrating a synergic effect of that macrocycle on the reaction kinetics decreasing further the overpotential of the oxygen evolution reaction. In fact, α-NiFeOCPc@rGO-K was the ternary composite material with best performance, being able to sustain a stable current of 10 mA cm−2 during 8 h of continuous electrolysis at 1.64 V vs RHE, in 1.0 mol dm−3 KOH solution, showing good perspectives as electrode material for OER.