Disordered TiOx-SiOx Nanocatalysts Using Bioinspired Synthetic Routes

Metal oxide nanomaterials have increasing significance and broad applications in catalysis, ranging from support materials to active catalysts. In this paper, we have demonstrated a facile synthetic strategy to create disordered, high-surface-area metal oxide nanomaterials using biomineralization-inspired methods. Using protamine as a protein template, a range of TiOx-SiOx nanomaterials were synthesized and implemented for catalytic CO2 thermal reduction reactions. The modularity of synthetic options afforded via biomineralization enables increases in surface area, which are ideally suited for subsequent modification to regulate catalytic performance. All materials were thoroughly characterized using a suite of synchrotron scattering and spectroscopic methods. Through these techniques, we have demonstrated that protamine-induced biomineralization results in largely disordered materials with changes in the local atomic structure dependent on the applied synthetic conditions. Protamine removal with treatment under acidic conditions greatly increased material surface area while causing measurable changes in the structure as revealed by X-ray absorption spectroscopy. Upon subsequent hydrogenation, Ti- and Si-based defects were induced in the materials while the disordered nature of the material was still largely retained. Furthermore, we found that the incorporation of Si into TiOx was able to mitigate the known anatase to rutile phase change during the reaction while stabilizing the defect sites. The synthetic strategies described in this work are expected to be translatable to other metal oxide nanomaterial chemical structures, providing a means to control catalytic properties using benign synthetic strategies.

Automated summary

Metal oxide nanomaterials synthesized using a biomineralization-inspired method have been shown to have increased surface area and controllable catalytic properties. The use of protamine as a protein template resulted in largely disordered materials with changes in atomic structure dependent on synthetic conditions. Removal of protamine and subsequent hydrogenation induced defects in the materials while retaining their disordered nature, showing potential for controlling catalytic properties using benign synthetic strategies.