Cobalt chromium-layered double hydroxide, α- and β- Co(OH)2 and amorphous Cr(OH)3: synthesis, modification and characterization

Ofeliya O Balayeva; Abdulsaid A Azizov; Mustafa B Muradov; Rasim M Alosmanov; Goncha M Eyvazova; Sevinj J Mammadyarova

doi:10.1016/j.heliyon.2019.e02725

Cobalt chromium-layered double hydroxide, α- and β- Co(OH)₂ and amorphous Cr(OH)₃: synthesis, modification and characterization

Heliyon. 2019 Nov 14;5(11):e02725. doi: 10.1016/j.heliyon.2019.e02725. eCollection 2019 Nov.

Authors

Ofeliya O Balayeva¹, Abdulsaid A Azizov¹, Mustafa B Muradov², Rasim M Alosmanov¹, Goncha M Eyvazova², Sevinj J Mammadyarova²

Affiliations

¹ Department of Chemistry, Baku State University, Z. Khalilov str., 23, AZ-1148 Baku, Azerbaijan.
² Department of Physics, Baku State University, Z. Khalilov str., 23, AZ-1148 Baku, Azerbaijan.

Abstract

Cobalt-chromium layered double hydroxide (CoCr LDH), α- and β- Co(OH)₂ and amorphous Cr(OH)₃ have been synthesized under different reaction conditions. The obtained CoCr LDH was modified by stearic acid (SA) and sodium stearate (SS). The obtained samples have been characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Ultraviolet-visible- (UV-Vis), Fourier transform infrared- (FTIR) and Energy-dispersive X-ray- (EDX) spectroscopy. The influence of reaction conditions on product composition, structural and optical properties of the samples have been discussed in detail. The basal spacing of CoCr-LDH increased from 7.366 Å to 7.428 Å and 25.214Å after the intercalation by stearic acid and sodium stearate, respectively. The average particles size by SEM analyze was estimated to be approximately 100-150 nm and 30-50 nm for CoCr-LDH_0.6M(90°C) and CoCr-LDH_0.6M(90°C)/SS nanostructures, respectively. Mixed hydroxides like α- and β- Co(OH)₂ have been obtained along with LDH at lower pH value (pH ∼ 7). The number of diffraction peaks corresponding to β-Co(OH)₂ has increased with relatively decreasing of Co²⁺ ions in the reaction medium. At high chromium concentrations (Co²⁺:Cr³⁺ = 1:3 and 1:5), amorphous Cr(OH)₃ were formed in the experiment.

Keywords: Basal spacing; Chemistry; Functional group; Layered double hydroxide; Materials characterization; Materials processing; Materials science; Materials structure; Materials synthesis; Nanomaterials; Reaction proceedings; Sodium stearate; Stearic acid.