Novel coating materials are constantly
needed for current and future
applications in the area of microelectronics, biocompatible materials,
and energy-related devices. Molecular layer deposition (MLD) is answering
this cry and is an increasingly important coating method for organic
and hybrid organic–inorganic thin films. In this study, we
have focused on hybrid inorganic–organic coatings, based on
trimethylaluminum, monofunctional aromatic precursors, and ring-opening
reactions with ozone. We present the MLD processes, where the films
are produced with trimethylaluminum, one of the three aromatic precursors
(phenol, 3-(trifluoromethyl)phenol, and 2-fluoro-4-(trifluoromethyl)benzaldehyde),
ozone, and the fourth precursor, hydrogen peroxide. According to the
in situ Fourier-transform infrared spectroscopy measurements, the
hydrogen peroxide reacts with the surface carboxylic acid group, forming
a peroxyacid structure (C(O)–O–OH), in the case of all
three processes. In addition, molecular modeling for the processes
with three different aromatic precursors was carried out. When combining
these modeling results with the experimental research data, new interesting
aspects of the film growth, reactions, and properties are exploited.
Atomic layer deposition (ALD) was used to deposit protective overcoating (Al2O3) on an industrially relevant Co-based Fischer-Tropsch catalyst. A trimethylaluminium/water (TMA/H2O) ALD process was used to prepare ~0.7 – 2.2...
A liquid organic hydrogen carrier (LOHC) is an interesting concept for hydrogen storage. Pt supported on a rutile-anatase form of titania was found to be an active catalyst system for dehydrogenation of perhydrogenated dibenzyl toluene.
Atomic layer deposition (ALD) was used to prepare a thin alumina layer on Fischer–Tropsch catalysts. Co-Pt-Si/γ-Al2O3 catalyst was overcoated with 15–40 cycles of Al2O3 deposited from trimethylaluminum (TMA) and water vapor, followed by thermal annealing. The resulting tailored Fischer–Tropsch catalyst with 35 cycle ALD overcoating had increased activity compared to unmodified catalyst. The increase in activity was achieved without significant loss of selectivity towards heavier hydrocarbons. Altered catalyst properties were assumed to result from cobalt particle stabilization by ALD alumina overcoating and nanoscale porosity of the overcoating. In addition to optimal thickness of the overcoat, thermal annealing was an essential part of preparing ALD overcoated catalyst.
The growth mechanism of Atomic Layer Deposition (ALD) on polymeric surfaces differs from growth on inorganic solid substrates, such as silicon wafer or glass. In this paper, we report the growth experiments of Al2O3 and ZnO on nonwoven poly-L-lactic acid (PLLA), polyethersulphone (PES) and cellulose acetate (CA) fibres. Material growth in both ALD and infiltration mode was studied. The structures were examined with a scanning electron microscope (SEM), scanning transmission electron microscope (STEM), attenuated total reflectance-fourier-transform infrared spectroscopy (ATR-FTIR) and 27Al nuclear magnetic resonance (NMR). Furthermore, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were used to explore the effect of ALD deposition on the thermal properties of the CA polymer. According to the SEM, STEM and ATR-FTIR analysis, the growth of Al2O3 was more uniform than ZnO on each of the polymers studied. In addition, according to ATR-FTIR spectroscopy, the infiltration resulted in interactions between the polymers and the ALD precursors. Thermal analysis (TGA/DSC) revealed a slower depolymerization process and better thermal resistance upon heating both in ALD-coated and infiltrated fibres, more pronounced on the latter type of structures, as seen from smaller endothermic peaks on TA.
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