Cubic Nanostructures of Nickel–Cobalt Carbonate Hydroxide Hydrate as a High-Performance Oxygen Evolution Reaction Electrocatalyst in Alkaline and Near-Neutral Media

Abstract

Catalyst development for the efficient direction of electrocatalytic water splitting with much less overpotential is crucial for meeting large-scale hydrogen generation. Being highly abundant and cost-effective, 3d transition-metal-based catalysts show promising activities in alkaline conditions. In this work, bimetallic nickel−cobalt carbonate hydroxide hydrate (NiCo-CHH) was prepared by a co-precipitation method with varying molar ratios of Ni/Co of 0.5:1, 1:1, and 1.5:1, which were analyzed for oxygen evolution reaction (OER) study in both alkaline (1 M KOH) and near-neutral (1 M NaHCO 3 ) media. For OER in 1 M KOH, NiCoCHH 1:1 required overpotential of just 238 mV at 10 mA cm −2 current density compared to other ratios of 0.5:1 and 1.5:1, which required 290 and 308 mV, respectively. Similarly, in 1 M NaHCO 3 , NiCoCHH 1:1 required an overpotential of 623 mV to reach 10 mA cm −2 . A post-OER study confirmed the formation of NiOOH during OER. The observed faradaic efficiency was nearly 95.21% for the NiCoCHH 1:1 catalyst. A two-electrode setup with NiCoCHH 1:1∥Pt required just 312 mV as an overpotential at 10 mA cm −2 . These kinds of comparative studies can be used in other 3d transition-metal-based catalysts for OER in the future.

Controllable Morphology of Sea-Urchin-like Nickel–Cobalt Carbonate Hydroxide as a Supercapacitor Electrode with Battery-like Behavior

“…The extra peak at 287.6 and 289.0 is ascribed to the carbon hydroxyl and C carbonate species, respectively. 34,35,37 Thus, these results suggest the main valence state of nickel−cobalt complex is Ni 2+ , Co 2+ , and Co 3+ , which is in good agreement with the previous report of the mixed nickel−cobalt carbonate hydroxide.…”

“…The deconvoluted C 1s spectra (Figure e) are also observed at 283.6 and 285.3 eV, corresponding with the characteristic binding energy of Ni carbonate and Co carbonate species, respectively. The extra peak at 287.6 and 289.0 is ascribed to the carbon hydroxyl and C carbonate species, respectively. ,, Thus, these results suggest the main valence state of nickel–cobalt complex is Ni 2+ , Co 2+ , and Co 3+ , which is in good agreement with the previous report of the mixed nickel–cobalt carbonate hydroxide.…”

“…The peaks at 798.5 and 782.9 eV correspond with Co 2p 3/2 and 2p 1/2 of Co 2+ . In addition, the peaks at 792.7 and 776.1 eV are attributed to Co 2p 3/2 and 2p 1/2 of Co 3+ . Two species of oxygen are observed in Figure d.…”

“…In addition, the peaks at 792.7 and 776.1 eV are attributed to Co 2p 3/2 and 2p 1/2 of Co 3+ . 37 Two species of oxygen are observed in Figure 4d. The higher intensity peak at 533.0 eV can be ascribed as a typical metal carbonate species while the peak at 532.1 eV is designated to hydroxyl groups.…”

MoS2 Decoration Followed by P Inclusion over Ni-Co Bimetallic Metal–Organic Framework-Derived Heterostructures for Water Splitting

“…Heretofore, various transition metal-based oxides, oxyhydroxides, nitrides, carbides, sulfides, and phosphides have been explored as catalysts for the overall water splitting. − Among them, transition metal sulfides (TMSs) are more promising electrocatalysts for water splitting. However, a handful of articles reported that the TMSs’ inappropriate surface electronic structure negatively influences the OER and HER activity because of their weak adsorption of oxygen-containing intermediates.…”