Ultrasound-assisted hexamethylenetetramine decomposition for the synthesis of alpha nickel hydroxide intercalated with different anions

Abstract

Alpha nickel hydroxide was prepared by the sonochemical degradation of hexamethylenetetramine at elevated temperatures using chloride, acetate, nitrate, and sulfate nickel salts. This method yielded dense layered structures with two different interlayer spacing of 11 and 8 Å. The specific capacitance of these samples was further improved by the addition of extra anions to the reaction mixtures in the form of sodium salts. This approach yielded structures in flowerlike morphology with a single interlayer spacing of 8 Å. The sulfate-intercalated sample, however, formed the flowerlike morphology even without the addition of extra anions. The highest specific capacitance value of 543 F g −1 , at a scan rate of 50 mV s −1 , was obtained for sulfate-intercalated sample with extra anions. The differences due to different anions likely arise from size of their solvation shells and the distance between the anions and hydroxide layer. Anions surrounded tightly by water molecules are located farther from the hydroxide layers, interact less strongly and therefore are more labile and lead to higher specific capacitance values.

First‐Row Transition‐Metal Cations (Co2+, Ni2+, Mn2+, Fe2+) and Graphene (Oxide) Composites: From Structural Properties to Electrochemical Applications

“…This may be due to the higher metal content in Fe/GO with respect to the other metals. Additionally, a sharp peak appeared at =3630 cm −1 in the IR spectrum of Co/GO, which belongs to free O−H stretching originating from a hydroxide group not interacting with water molecules . The presence of the free OH band in Co/GO is probably related to the formation of Co(OH) 2 during KOH washing, as explained in the sample preparation part for characterization.…”

Facile Synthesis of Graphene Aerogel Supported Nickel/Nickel Oxide Core–Shell Nanoparticles: Efficient Electrocatalysts for Oxygen Evolution Reactions

“…In all of the voltammograms of Ni/NiO/GA, a couple of redox peaks was observed, in which the anodic peak was centered around 1.34 V (vs RHE) (Figure S11). This region is known as the “oxyhydroxide region”, and the anodic peak indicates oxidation of the Ni­(OH) 2 layer formed on top of the air-formed NiO layer to NiOOH according to the following equation: ,, …”

Influence of ultrasound and template on the properties of nickel hydroxide as an active substance of supercapacitors

“…Ultrasound can be applied during the synthesis of α-Ni(OH) 2 [34,35], and also for β-Ni(OH) 2 [36,37]. This allows for the controlled synthesis with the selection of α or β form [38]. When synthesizing β-Ni(OH) 2 using ultrasound, the formation of the hydroxide with nanosized [39] or microsized particles [40] or mesoporous hydroxide [41] is possible.…”