Synthesis of High Surface Area—Group 13—Metal Oxides via Atomic Layer Deposition on Mesoporous Silica

Abstract

The atomic layer deposition of gallium and indium oxide was investigated on mesoporous silica powder and compared to the related aluminum oxide process. The respective oxide (GaOx, InOx) was deposited using sequential dosing of trimethylgallium or trimethylindium and water at 150 °C. In-situ thermogravimetry provided direct insight into the growth rates and deposition behavior. The highly amorphous and well-dispersed nature of the oxides was shown by XRD and STEM EDX-mappings. N2 sorption analysis revealed that both ALD processes resulted in high specific surface areas while maintaining the pore structure. The stoichiometry of GaOx and InOx was suggested by thermogravimetry and confirmed by XPS. FTIR and solid-state NMR were conducted to investigate the ligand deposition behavior and thermogravimetric data helped estimate the layer thicknesses. Finally, this study provides a deeper understanding of ALD on powder substrates and enables the precise synthesis of high surface area metal oxides for catalytic applications.

Quantification and Tuning of Surface Oxygen Vacancies for the Hydrogenation of CO2 on Indium Oxide Catalysts

“…Therefore, the ratio between the exposed indium sites and total indium was higher on the IWI sample, which might be caused by the lower loading (8 wt % vs. 14 wt % In). It was previously shown that a monolayer of In 2 O 3 is formed after the second ALD cycle [56]. Hence, some indium atoms are already located in the sublayer after two ALD cycles.…”

“…In this study, ALD experiments were carried out in a selfdesigned setup of which a detailed description is given elsewhere [55]. Trimethylindium (TMI) and water were used as precursor-reactant combination and the overall ALD process investigation is described in detail in [56]. Initially, the ALD growth behavior was validated by in situ thermogravimetric studies in a magnetic suspension balance (SI Fig.…”

“…Therefore, ALD resulted in a higher dispersion of indium on ZrO 2 , which agrees with the XRD results. Generally, agglomeration is prevented by ALD as the deposition is limited by the number of reactive sites [41,56].…”

“…The higher abundance of OH groups on the ALD sample can be rationalized by the usage of H 2 O as reagent during synthesis. Furthermore, it was shown that ALD favored the deposition of In(OH) x in the first cycles [56].…”

Synthesis and Selenization of Thickness-Controllable In2O3 Films by Printed Oxide Skin of Liquid Metals

“…Recently, a lot of methods have been developed to prepare atomically thin oxide films. Solution-phase synthesis can be applied simply in the commercial production of oxide films. , Magnetron sputtering and other vapor deposition methods could prepare uniformly distributed oxides. − However, the thickness of the metal oxide films fabricated by solution-phase synthesis is uncontrollable, and the oxide films using physical methods are generally polycrystalline, which can result in unstable electrical properties due to grain boundaries, thus leading to unstable electronic properties. Hereby, finding a scalable and simple method for realizing thickness controllability is the key factor in fabricating atomically thin metal oxide films.…”