Nanoparticle assembly of ordered multicomponent mesostructured metal oxides via a versatile sol-gel process

Multicomponent metal oxides have attracted attention for their potential use in electronic, (photo)catalytic, photovoltaic, and energy storage applications. The ability to simultaneously control the nanoscale structure and composition of such materials using simple and inexpensive routes is important for that potential to be realized. Here we introduce a simple and widely applicable methodology for the synthesis of multicomponent mesostructured metal oxides (MMMOs) from the combination of inexpensive and commercially available polymers with metal alkoxides solubilized in a sol-gel solution consisting of acetic acid, hydrochloric acid, and ethanol (AcHE). MMMOs obtained utilizing the AcHE system have tunable pore structures, a high degree homogeneity, and in certain cases thermal stability above 1000 degrees C. The ability to easily process these diverse MMMOs in the form of thin films, free-standing membranes, and monoliths provides distinct advantages over previously reported MMO synthesis proceduresespecially when large quantities of material are required, for instance, in heterogeneous catalyst development. Most importantly, we demonstrate that the controlled binding of reactive metal ions with acetic acid in the AcHE solution yields nanometer-sized particles for a diverse collection of inorganic materials with homogeneous condensation kinetics. This allows for the simple synthesis of complicated and novel MMMO compositions (e.g., rare earth and mixed transition metal oxides) via cooperative assembly with amphiphilic block copolymers. The development of such simple and widely applicable methodologies are extremely important for the practical implementation of porous metal oxides.