Due to their various applications, metal oxides are of high interest for fundamental research and commercial usage. Per applications as catalysts or electrochemical devices, the tailored design of metal oxides featuring a high specific surface area and additional functionalities is of the utmost importance for the performance of the resulting materials. We report a new method for preparing free-standing films consisting of hierarchically porous metal oxides (titanium and niobium based) by combining emulsion polymerization and shear-induced monodisperse particle self-assembly in the presence of sol−gel precursors. After thermal treatment, the resulting porous materials can be used as electrodes in Li-ion batteries. The titanium and niobium sol−gel precursors were partially immobilized to the surface of organic core−interlayer particles featuring hydroxyl groups to obtain hybrid organic− inorganic particles through the melt−shear organization process. Free-standing particle-based films, in analogy to elastomeric opal films and colloidal crystals, can be prepared in a convenient one-step preparation process. After thermal treatment, ordered pores are obtained, while the pristine metal oxide precursor shell can be converted to the (mixed) metal oxide matrix. Heat treatment under CO 2 leads to mixed-TiNb oxide/carbon hybrid materials. The highly porous derivative structure enhances electrolyte permeation. When tested as Li-ion battery electrodes, it shows a specific capacity of 335 mAh•g −1 at a rate of 10 mA•g −1 . After 1000 cycles at 250 mA•g −1 , the electrodes still provided a specific capacity of 191 mAh•g −1 .

Mixed-metal oxides (MMOx), oxides with more than one (transition) metal, provide versatile structural and electrochemical properties well exploited in energy conversion and electrochemical energy storage. The preparation of MMOx from single-source precursors benefits from homogeneous composition and uniform metal distribution. Herein, we describe layered mixed-metal carbides (MXenes) as templates to prepare MMOx. Through thermal oxidation of TiNb-based MXenes in CO 2 , mixtures of Ti and Nb oxides were produced. The Ti-to-Nb ratio in the MXene significantly affects the derived oxide composition but does not show a direct stoichiometric relation between them. At higher Ti ratios, oxide mixtures of TiO 2 and titanium niobium oxide are obtained, while with Nb excess, only MMOx are produced. Multilayer MXenes retain carbon upon oxidation and produce TiNbO x /C hybrids, while delaminated MXenes lead to pure TiNbO x . When tested as Li-ion battery electrodes, the multilayer MXene-derived MMOx with Ti/Nb = 1:5 presented 226 mAh•g −1 at 10 mA•g −1 and 75% retention after 1000 cycles at 1 A•g −1 .