Synthesis of Highly Porous Metal Oxide Nanoparticles for Adsorption Applications

Herein, we report a general and straightforward synthesis method for large-pore highly mesoporous metal oxide nanoparticles via a modified inverse micelle formation. The role of diols as solvents has been demonstrated and extended to other metal oxides using ethylene glycol. After scanning most of the metals from the periodic table, magnesium and calcium from the s-block; tin from the p-block; vanadium, nickel, zinc, zirconium, and hafnium from the d-block; and lanthanum and cerium from the f-block elements, all these have been successfully synthesized as large-pore-diameter metal oxides. Because of thermodynamic stability of chelate formation, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol give a higher pore diameter, whereas a further increase in the diol carbon chain (1,6-hexanediol and 1,12-dodecandiol) leads to pore contraction. By varying the synthesis temperature, the effect of viscosity on the pore diameter has also been demonstrated. Potential applications of oxides of magnesium have been tested for carbon dioxide capture and adsorption of macromolecules such as proteins and lipids and small molecules such as curcumin, dopamine, and sucrose. As predicted, larger-pore-diameter and higher-pore-volume mesoporous magnesium oxide shows higher carbon dioxide capture and adsorption compared to commercial magnesium oxide. A mechanism for the higher pore diameters of mesoporous metal oxide nanomaterials has been proposed based on the results and previous reported literature studies.