Integrated Polyphenol-Based Hydrogel Templating Method for Functional and Structured Oxidic Nanomaterials

A straightforward fabrication method for tunable nanomaterials remains a key objective in the research areas of template chemistry, catalysis, and energy storage materials. A growing focus in materials chemistry is the development of structuring methods that are simple, scalable, and, at the same time, feasible with environmentally benign chemicals. We present a hydrogel-mediated templating method that yields customizable, porous transition-metal oxides. The protocol is extremely simple and includes predominately naturally occurring compounds. For example, the incorporation of sacrificial polymer latex into a polyphenolic hydrogel network produces xerogel composites with various filler contents. Voids are generated simultaneously during the pyrolysis of the dried gel, allowing for controlling the threedimensional (3D) arrangement of titania nanocrystals. As a proof of concept, we use the produced macroporous titania as a negative electrode (anode) material in lithium-ion batteries. We demonstrate that the gel-derived macroporous anatase significantly reduces the capacity loss compared to its commercial or nonporous analogues. The modularity of this one-pot templating protocol is further demonstrated by the fabrication of titanate nanostructures and porous zirconia.