Nanosheets of NiCo₂O₄/NiO as Efficient and Stable Electrocatalyst for Oxygen Evolution Reaction

Abstract

Development of a stable catalyst that can efficiently function for longer time for energy conversion process in water splitting is a challenging work. Here, NiCo 2 O 4 /NiO nanosheets are successfully synthesized following a simple wet-chemical route, followed by the combustion technique. Finally, the synthesized catalyst NiCo 2 O 4 /NiO can function as an efficient catalyst for oxygen evolution reaction. Nanosheets with interconnections are very useful for better electron transportation because the pores in between the sheets are useful for the diffusion of electrolyte in electrocatalysis. In oxygen evolution reaction, these sheets can generate current densities of 10 and 20 mA/cm 2 , respectively, upon application of 1.59 and 1.62 V potential versus reversible hydrogen electrode (RHE) under alkaline condition. In contrast, bare NiCo 2 O 4 nanowire bundles can generate a current density of 10 mA/cm 2 upon application of 1.66 V versus RHE. The presence of NiO in NiCo 2 O 4 /NiO nanosheets helps to increase the conductivity, which further increases the electrocatalytic activity of NiCo 2 O 4 /NiO nanosheets.

Highly Active and Easily Fabricated NiCo2O4 Nanoflowers for Enhanced Methanol Oxidation

“…These two peaks confirming the presence of Ni 2+ and Ni 3+ pairs, respectively. The other two broad peaks at approximately 881.3 eV and 862.7 eV correspond to satellite peaks …”

“…The other two peaks are shake‐up satellites (sat.) peaks . By analyzing the XPS (O 1s) oxygen peak, it can be deconvoluted to 3 peaks.…”

“…The other two broad peaks at approximately 881.3 eV and 862.7 eV correspond to satellite peaks. [17,29] Cobalt spectrum (Co 2p) is shown in Figure 5.c, two sharp peaks appear at about 781.4 eV and 796.95 eV. These two peaks are assigned to the Co 2p 3/2 and Co 2p 1/2 electronic states, which correspond to Co 2 + and Co 3 + , respectively.…”

“…peaks. [30,29] By 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 analyzing the XPS (O 1s) oxygen peak, it can be deconvoluted to 3 peaks. O1 peak at about 529.8 eV is associated with the metal-oxygen bonds of O-Ni/Co, while Ni-OH peak is linked to O 2 peak at 530.4 eV.…”

Electrochemical Water Oxidation in Acidic Solution Using Titanium Diboride (TiB2) Catalyst

“…[8] Thus, active, stable, and earth-abundant electrocatalysts for this oxygen-evolution reaction (OER) must be simultaneously developed. Such catalysts have been demonstrated in alkaline [3,[9][10][11][12][13] and neutral solutions, [14][15][16] but few examples have been reported in acidic media. [17] Acidic electrolytes are attractive as they are compatible with existing fuel-cell technologies, and with proton-exchange membrane-based electrolyzer systems that operate under high current densities and pressures.…”