In recent years, there has been increased effort towards the nanostructuring of catalyst materials, driven in part by the desire to increase surface-to-volume ratios, tune reactive site chemistry, and improve catalyst stability. One promising method for depositing nanostructured materials is layer-by-layer processing, in which an alternating sequence of self-limiting vapor-phase reactions is used to grow ultrathin coatings on even high aspect ratio supports, with precise control over the film thickness and composition. By combining a metal precursor typically associated with atomic layer deposition and an organic counter reactant monomer associated with molecular layer deposition (MLD), films of catalytically relevant materials can be grown with a carbon-based component that can be easily removed, allowing for further nanostructuring.<br/><br/>Here, we discuss the deposition of a hybrid organic-manganese film (known as a "manganicone") using MLD and the precursors bis(ethylcyclopentadienyl)manganese and ethylene glycol. Manganese oxide films show potential as promising earth abundant catalysts for various reactions, such as the oxygen evolution and reduction reactions (OER and ORR, respectively), the reduction of hydrogen peroxide, and as a promoter for the Fischer-Tropsch reaction. As-deposited films are characterized using a combination of variable angle spectroscopic ellipsometry (VASE), Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS) to verify the self-limiting nature of this layer-by-layer process and the successful reaction of the precursors. Time-resolved VASE suggests that the organic component of the films is unstable in air over a time frame that can be controlled through the addition of a blocking layer or through chemical and temperature treatments. Characterization of the stabilized and degraded films with atomic force microscopy, scanning electron microscopy, x-ray reflectivity, and XPS show the extent of organic degradation and removal. Finally, the results of testing the manganicone films for use as a catalyst, including the OER/ORR reaction, will be discussed.

Molecular layer deposition of ultrathin manganese oxide hybrid materials for catalysis applications

253rd National Meeting (2017)

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