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 . 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 . 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.