Effect of Crystallinity of β- and β_bc-Nickel Hydroxide Samples on Chemical Cycling

Abstract

-phases of nickel hydroxide and cobalt hydroxide samples crystallize in cadmium iodide type structure. -cobalt hydroxide on oxidation generates -CoOOH which crystallized in 3R 1 polytype while the structure of -phase of NiOOH polytype is less well understood. -and bc -phases of nickel hydroxide samples were prepared by using ammonium hydroxide and sodium hydroxide as precipitating agents. Powder X-ray diffraction data shows that -phase of nickel hydroxide is perfectly crystalline in nature while bc -phase of nickel hydroxide is poorly ordered. -and bc -phases of nickel hydroxide samples were subjected to chemical oxidation using sodium hypochlorite. The oxidized phases of -and bc -phases of nickel oxyhydroxide are highly disordered and the broadening of reflections in the powder X-ray diffraction patterns is due to the presence of structural disorder, variations in the crystallite size, and strain. On reduction of -and bc -phases of nickel oxyhydroxide, the powder X-ray diffraction patterns visually match the powder X-ray diffraction data of the pristine phases of -and bc -phases of nickel hydroxide indicating that the -phase of nickel hydroxide does not transform to bc -phase of nickel hydroxide, but the particle sizes are significantly affected.

Electrochemical measurements of synthesized nanostructured β-Ni(OH)2 using hydrothermal process and activated carbon based nanoelectroactive materials

“…In the case of NiOH-3, the product has the highest specific capacitance value about 4697 F g −1 at 5 mV s −1 . Consequently, this is due to the fact that the electrochemical performances of β bcnickel hydroxide are higher than that of β-nickel hydroxide [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. These values are higher than those obtained in literature for other hydroxide nanocomposites [14,16,33,[35][36][37][38][39][40] (as summarized in Table 2).…”

“…Raman Shift (cm ) Fig. 3 Raman spectra of the obtained β-phase Ni(OH) 2 hydroxide using hydrothermal method at different conditions β bc -Ni(OH) 2 structural phase formation according to the literature [20,22]. So, the obtained peaks at 312 and 447 cm −1 can be ascribed to the E-type vibration of the Ni-OH lattice and the Ni-O stretch, respectively.…”

Generalizable, Electroless, Template-Assisted Synthesis and Electrocatalytic Mechanistic Understanding of Perovskite LaNiO3 Nanorods as Viable, Supportless Oxygen Evolution Reaction Catalysts in Alkaline Media

“…The resulting dried “white-to-pale green” powder was subsequently left to soak within a 2.5 M NaOH/1.25% NaClO solution for 1.5 h, with the first 10 min under mild sonication. The dispersion darkened in hue, as Ni­(OH) 2 was converted into NiOOH, as described by eq 3 in Table . Upon centrifugation of the dispersion, a brown-black powder was isolated and washed with deionized (DI) water four times to remove excess NaOH and NaClO.…”

“…The dispersion darkened in hue, as Ni(OH) 2 was converted into NiOOH, as described by eq 3 in Table 1. 41 Upon centrifugation of the dispersion, a brown-black powder was isolated and washed with deionized (DI) water four times to remove excess NaOH and NaClO. Ultimately, the powder was air-dried at 80 °C.…”

Effect of variable temperature loads on characteristics of electrochrome composite Ni (OH)2-PVA films

“…Interestingly, after temperature tests in alkali, the shape of the curves changed significantly. Obviously, this is due to the fact that there were changes in the structure associated with the decomposition of α-Ni(OH) 2 , which was obtained electrochemically and transformed into β-Ni(OH) 2 and other phases [23][24][25][26][27][28].…”