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The electrochemical behaviour of nanocrystalline nickel: A comparison with polycrystalline nickel under the same experimental condition

“…The value of the same order of magnitude or slightly lower were reported in the literature for polycrystalline Ni. The same order of magnitude was reported by Boinet et al [24] for passive Ni in neutral and slightly alkaline borate buffer solutions and Darowicki et al [33] for passive Ni in 1 M NaOH at a frequency of 1 kHz. Several authors reported slightly smaller values; Barral et al [31] reported N A = 9.8 Â 10 20 cm À3 for a passive Ni electrode in 1 M KOH, Sikora and Macdonald [26] The flat-band potential E fb of the passive film, examined from Fig.…”

“…Incorporation of other ions in the passive film structure and their contribution to the mass changes is ignored because the recent spectroscopic and electrochemical studies [22][23][24] have shown that the passive film is mainly formed by Ni(OH) 2 at the early stages of Ni passivation. Because the dissolution of Ni 2+ from oxide into solution contributes to a decrease in mass, while the uptake of OH À from solution into oxide contributes to an increase in mass, Eq.…”

Electrochemical Growth of Surface Oxides on Nickel. Part 1: Formation of α-Ni(OH)2 in Relation to the Polarization Potential, Polarization Time, and Temperature

“…There is a well-defined linear region having a negative slope in the 0.60-0.75 V potential range, which indicates that the surface hydroxide layer is a p-type semiconductor. At potentials lower than 0.60 V, the plot is non-linear and this behavior is in [29,41,42,71,72]. The main graph reveals a smaller value of C t -2 (a large value of C t ) in the case of a Ni(poly) electrode covered with a layer of α-Ni(OH) 2 than in the case of Ni(poly) covered with a layer of β-Ni(OH) 2 .…”

High Current Density Oxygen Evolution in Carbonate Buffered Solution Achieved by Active Site Densification and Electrolyte Engineering

“…The OER operations in carbonate (pH 9.5) and phosphate (pH 10.5) solutions, which are away from the buffer pK a (carbonate: 10.3, phosphate: 12.4, 7.2), [43] had increased potential due to insufficient buffering capacity (Figure 1b). Literature proposed that borate species [H 3 BO 3 and B(OH) 4 À ] adsorbs on the oxide surface by coordinating with the metal centers, as proposed on nickel or iron oxide surface, [44,45] or the formation of nickel-borate complex oxide proposed by Nocera and co-workers, [46] which can impede metal dissolution and prevent electrode degradation.…”