Nanoflower, nanoplatelet and nanocapsule Mg(OH)2 powders for adsorption of CO2 gas

The soft chemical synthesis of self-assembled magnesium hydroxide (Mg(OH)2) nanoplatelets with surface area as high as about 300 m2 g−1 was achieved in the present work. The nanopowders such as MHN, MHCl, MHBr were synthesized at ~30 °C without using any catalyst or surfactant using, respectively, precursor solutions of Mg(NO3)2, MgCl2, MgBr2 and characterized by XRD, BET surface area, BJH pore size analysis, FTIR, FE-SEM, TEM and EDX techniques. It was found that the MHN and MHCl nanopowders comprised of nanoflowers formed by self-assembly of nanoplatelets and porous nanoplatelets, while the MHBr nanopowders comprised of a random assembly of nanocapsules. The powders possessed the technologically important quality of reproducible CO2 adsorption at room temperature and its desorption at a relatively lower temperature of 75 °C. Based on the experimental evidences, the mechanisms of various microstructure formations and CO2 adsorption mechanism were also proposed.