ALD of Ultrathin Ternary Oxide Electrocatalysts for Water Splitting

Abstract

Semiconducting oxides, particularly mixtures of different transition-metal oxides, are promising materials for oxygen evolution reaction (OER) catalysts. Assessment of these materials is often complicated by inadequate dispersion of the materials, charge transport limitations, and lack of surface area characterization. Thin films deposited by atomic layer deposition (ALD) present an excellent way to overcome these issues. Here, we present the first work using ALD to investigate ternary oxide electrocatalysts, specifically with the Ti–Mn ternary oxide system. Thin-film mixtures of between 1.4 and 2.8 nm in thickness are successfully synthesized by ALD and show a high degree of mixing. At compositions between ∼10 and 70% Mn:(Mn+Ti), there is a reduction in ALD growth rate relative to the growth rates of the binary constituents. Moreover, we observe a shift in the chemical binding energies of both Mn and Ti over this composition range. An elevation in the activity of Mn active sites for OER is observed with increasing MnO x content in TiO2, increasing the turnover frequency (TOF) by approximately an order of magnitude. These results are consistent with previous DFT calculations. We also explore the effect of film thickness of the ternary metal oxide on catalytic activity, highlighting how ALD allows for charge transport limitations to be minimized.

Atomic layer deposition of GDC cathodic functional thin films for oxide ion incorporation enhancement

“…The doping ratio for each cycle ratio was estimated using the deposition rate of each material and the rule of mixture (ROM), which is used for calculating the composition of compound materials. 29 The estimated value of Gd 2 O 3 mol% for the ALD GDC samples ranged from 10 to 25 mol%. Doped-ceria materials show optimal characteristics for SOFC at doping ratios from 12 to 17 mol%.…”

“…As summarized in Table 1, the ALD cycle ratios between CeO 2 and Gd 2 O 3 were adjusted from 5:1 to 2:1 in this experiment. The doping ratio for each cycle ratio was estimated using the deposition rate of each material and the rule of mixture (ROM), which is used for calculating the composition of compound materials 29 . The estimated value of Gd 2 O 3 mol% for the ALD GDC samples ranged from 10 to 25 mol%.…”

Electrode Architecture in Galvanic and Electrolytic Energy Cells

“…[38][39][40] Aw ide array of synthetic approaches has been proposed for the creation of these ideal nanostructures,which can be grouped into either top-down or bottom-up approaches ( Figure 4). [44,45] Thechoice of the method depends on architectural scale. This includes using soft and hard templates, high-precision machinery,size reduction, or main-component dissolution.…”

“…[41][42][43] In the bottom-up approach, the electrode is built up atomby-atom, molecule-by-molecule,c luster-by-cluster,a nd particle-by-particle.F or example,electrodes have been fabricated using underpotential electrodeposition (UPD), layer-bylayer deposition (LBL), colloidal synthesis,a tomic layer deposition (ALD), and molecular layer deposition (MLD) for conformal coating of thin layers on asubstrate. [44,45] Thechoice of the method depends on architectural scale. Thebottom-up approach is the preferred choice for building up the nanoscale structure.T he essence of the electrode architecture formation from vapor,l iquid, or solid phase in the bottom-up approach is the nucleation and growth.…”

Elektrodenarchitektur in galvanischen und elektrolytischen Energiezellen

“…Beispielsweise wurden Elektroden unter Verwendung von niederpotentialer Elektroabscheidung (UPD), Schicht-für-Schicht-Abscheidung (LBL), Kolloidsynthese,A tomlagenabscheidung (ALD) und Moleküllagenabscheidung (MLD) zum konformen Aufschichten dünner Schichten auf ein Substrat hergestellt. [44,45] Die Wahl des Verfahrens hängt vom Grçßenmaßstab der Architektur ab.D er Bottom-up-Ansatz ist die bevorzugte Wahl zur Herstellung nanometergroßer Strukturen. Beim Bottom-up-Ansatz wird die Elektrodenstruktur aus der Dampf-, Flüssigkeits-oder festen Phase über Keimbildung und Wachstum aufgebaut.…”