Metal-oxide-based materials are of interest for a variety of catalytic applications in the production of renewable fuels. Computational researchers have predicted novel, often complex, stoichiometries and morphologies to enhance key properties of mixed-metal oxides, making them even more attractive. For example, recent calculations have suggested that co-doping anatase-TiO2 with pairs of donors (M' = transition metals Ta, Nb, W, Mo) and acceptors (E = main group elements N, C) to form TixM'1-xOnE1-n materials would positively impact the resulting photoelectrochemical properties. However, the synthesis of these targets represents a formidable task to chemists and materials scientists. In contrast to traditional thermal and sol-gel approaches, non-aqueous molecular precursor approaches have demonstrated success in accessing complex compositions, often at low temperatures. This methodology delivers accurate control of stoichiometry and homogeneous incorporation of elements, even when low mol ratios of M/M' are desired. Here we present our recent preparation, characterization, and catalytic investigation of TiO2-based oxynitride materials utilizing Ti(OtBu)4 as the Ti source and nitrido precursors N=M'(OtBu)3 (M' = Mo, W) to deliver both M' and N. The resulting oxynitrides, termed TixM'(ON)  (where x = 3, 10, 20), retain 75-85% of the N from the precursor. Important for PEC applications, the materials demonstrate significantly red-shifted light absorbance versus TiO2, with certain compositions absorbing into the infrared. The charge carrier dynamics and activity for photocatalytic degradation of methylene blue dye, both with visible light excitation, will be presented. Finally, applications of this methodology to access materials of interest outside of photocatalysis will also be discussed.

Molecular precursor approaches to the design and synthesis of catalytic materials for renewable fuels production

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.