Single-source precursor to complex metal oxide monoliths with tunable microstructures and properties: The case of Mg-containing materials

Synthesis of complex metal oxide monoliths (MgAl2O4, MgFe2O4, and In2-xMgxO3) with mamacropore frameworks through a novel single-source inorganic precursor route is successfully established. The synthesis approach mainly involves the formation of two-phase composite (desired complex metal oxide and MgO phases) monoliths induced by high-temperature sintering of layered double hydroxide (LDH) precursors, followed by a selective leaching of self-generated MgO sacrificial template from the sintered two-phase composites. The materials have been characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDX). The results indicate that the microstructures (morphologies, particle sizes, spacing among particles, and compositions) of resultant macroporous monoliths could be finely tuned by changing precursor compositions and sintering temperatures of precursors. Further investigation shows that these as-prepared monoliths display promising surface s uperhydrophobi city for organically modified MgAl2O4 spinels, ferromagnetism for MgFe2O4 ferrites, and semiconductor optical behaviors for Mg-doped In2O3. We believe that this method has a wide scope of application for the preparation of monoliths of complex metal oxides of macroporous type from suitable layered double hydroxides as the precursors.