Structurally Stable Manganese Alkoxide Films Grown by Hybrid Molecular Layer Deposition for Electrochemical Applications

Abstract

Hybrid molecular layer deposition (MLD) has significant potential for the creation of ultrathin electrochemically active materials, due to its ability to combine organic and inorganic species to modulate film properties. However, only a limited number of hybrid MLD processes are demonstrated with electrochemically relevant elements, such as manganese. Here, a "manganicone" manganese hybrid MLD chemistry is developed using the precursors bis(ethylcyclopentadienyl)manganese and ethylene glycol. The resulting manganese alkoxide coordination networks are shown to have many interesting properties, including the ability to seamlessly fill high aspect ratio vias and the chemical conversion into manganese carboxylate in air over several hours at room temperature. Linear, self-saturating growth is reported. Importantly, hybrid manganicone films annealed to 480 °C in air demonstrate a greater stability to restructuring during electrochemical testing than their inorganic counterparts grown by atomic layer deposition, without reducing the activity of the reactive sites on the manganese surface. Thus, hybrid manganese films grown by MLD have significant promise for use as catalysts for the oxygen evolution reaction and as electrodes in thin film batteries.

Chemical, Structural, and Electrical Changes in Molecular Layer-Deposited Hafnicone Thin Films after Thermal Processing

“…After the 350 °C anneal, the weak feature around 1400–1700 cm –1 becomes more intense (more clearly visible in Figure S2), and the CH 2 peak disappears possibly indicating the formation of carboxylate species due to the cleavage and oxidation of the alkoxides (CH 2 , C–O) from the EG linker and desorption of EG (these changes are also emphasized in FTIR difference spectra in Figure S3). − Only minor differences between the films that were annealed and those annealed under UV irradiation were observed. No evidence of crystalline HfO 2 was observed in the FTIR spectra upon heating up to 350 °C, consistent with the XRD observations that the films remain amorphous up to ∼600 °C.…”

“…The broad feature at 3330 cm –1 corresponds to the hydrogen bond between Hf–OH and Hf–OH species . The peaks at 1370 and 900 cm –1 correspond to the presence of COO – carboxylate species . The presence of hydroxyl and carboxylate peaks in the as-deposited sample may correspond to the slight oxidation of the samples due to the uptake of moisture from the atmosphere.…”

“… 55 The peaks at 1370 and 900 cm –1 correspond to the presence of COO – carboxylate species. 33 The presence of hydroxyl and carboxylate peaks in the as-deposited sample may correspond to the slight oxidation of the samples due to the uptake of moisture from the atmosphere. Upon annealing up to 250 °C, the intensity of –CH 2 peaks at 2860 and 2920 cm –1 and intensity of C–O peaks at 1090 cm –1 decrease.…”

Titanium Carboxylate Molecular Layer Deposited Hybrid Films as Protective Coatings for Lithium-Ion Batteries

“…At the same time the carboxylate stretching vibrations disappear and the film thickness decreases, implying the degradation of the film upon immersion in water. In the literature, the degradation of hybrid MLD films upon exposure to water is typically assigned to hydrolysis of the chemical bonds. − …”

Molecular Layer Deposition of “Magnesicone”, a Magnesium-based Hybrid Material

“…This is similar to the work on Mn-cone and Al-cone films. 24,33 For GL-grown magnesicone, about 46 at. % C, 11 at.…”