Investigation of the mechanism of nickel hydroxide formation from nickel nitrate

Nickel hydroxides are widely used as electrochemically active substances in alkaline batteries and hybrid supercapacitors; they can be for electrocatalysis, electrochemical sensors, pigments. Knowledge of the formation mechanism nickel is necessary developing optimizing targeted synthesis methods. The thermal effects processes hydroxide from nitrate were studied by calorimetry method. precipitate was investigated method simultaneous potentiometric (with a glass universal electrode) conductometric titration. content samples obtained at determined NaOH/Ni2+ ratios chemical trilonometry after preliminary dissolution. Calorimetric investigations showed that reaction with NaOH exothermic ΔНreaction=‒28328.5 J/mol. nature dilution process revealed ΔНdilution =‒2454 According to results titration, basic salt NiOHNO3 type not detected. Analysis titration two-stage nitrate. At first stage, which had high rate, due liquid-phase cation hydroxyl anion, primary composition Ni(OH)1.87(NO3)0.13 formed. In second result slow topochemical anions, ions displaced form hydroxide. These data confirmed analysis 1.87 2.2: Ni 52.95 % 55.63 %, corresponding formulas Ni(OH)1.87(NO3)0.13∙0.68H2O Ni(OH)2∙0.71H2O. This clearly indicated nitrate-doped α-Ni(OH)2 final corresponded α-modification