Synthesis of Highly Dispersed 2D Aluminum Cobalt Oxyhydroxide Compounds Based on Microwave-Activation Products of Crystalline Gibbsite

Abstract

We have studied interaction between the microwave activation product of gibbsite and an aqueous cobalt nitrate solution at room temperature, atmospheric pressure, and pH 8.0 ± 0.3. The results demonstrate that, under such conditions, the reaction in the near-surface region of the microwave-activated gibbsite particles leads to the formation of an aluminum cobalt oxyhydroxide with fragments of spinel structure and the composition Со_2.3Al_0.7O₄, and a Со_{6 –x}Al_{2 –x}(OH)_1.5 · 3.5H₂O (0 ≤ x ≤ 1) nonstoichiometric hydrotalcite. The morphology of such compounds is determined by 2D nanoparticles in the form of bent sheets 2–5 nm in thickness and 500 nm or more in length. After calcination at 500°C, the composition of the reaction products corresponds to the aluminum cobalt oxide Со_2.3Al_0.7O₄ with the spinel structure.