Synthesis of Metal Oxide Inverse Opals from Metal Nitrates by PMMA Colloidal Crystal Templating

Abstract

Metal oxide inverse opals are interesting for various applications. To achieve highly ordered inverse opal structures, one important issue during the colloidal crystal templating procedure is to form a stable precursor network before the template loses its structural integrity at high temperature. Using poly(methyl methacrylate), PMMA, colloidal crystal templates, it is essential to consider the physical and chemical changes of the precursors induced by the changes of PMMA during the thermal conversion. For a systematic investigation of this matter, we synthesized a variety of metal oxide inverse opals from the respective metal nitrates, including Cr2O3, Ga2O3, Fe2O3, In2O3, CuO, CeO2, and ZnO, to compare the effect of various modifications of precursors on the structural and optical properties. When the nitrate precursors have a lower thermal stability than the PMMA template, we have modified the metal nitrates by chelating or by polyacrylamide gelation to form more stable precursor networks.

Construction of Inverse–Opal ZnIn2S4 with Well–Defined 3D Porous Structure for Enhancing Photocatalytic H2 Production

“…It is foreseeable that the 3DOM semiconductor is a promising kind of photocatalyst. Regretfully, the reported IO photocatalysts are predominantly metal oxides, such as titanium oxide [25], tungsten oxide [18] and indium oxide [26], which usually have a wide bandgap and respond to UV light. Notably, due to the fact that the light utilization of the IO structure is mainly based on specific light with a slow effect in the red edge of the photonic crystal, it exhibits the best light absorption when this partial slow light highly overlaps with the band-edge region of the semiconductor.…”