Designing multifunctional CoOx layers for efficient and stable electrochemical energy conversion

Disordered and porous metal oxides are promising as earth-abundant and cost-effective alternatives to noble-metal electrocatalysts. Herein, we leverage non-saturated oxidation in plasma-enhanced atomic layer deposition to tune structural, mechanical, and optical properties of biphasic CoOx thin films, thereby tailoring their catalytic activities and chemical stabilities. To optimize the resulting film properties, we systematically vary the oxygen plasma power and exposure time in the deposition process. We find that short exposure times and low plasma powers incompletely oxidize the cobaltocene precursor to Co(OH)2 and result in the incorporation of carbon impurities. These Co(OH)2 films are highly porous and catalytically active, but their electrochemical stability is impacted by poor adhesion to the substrate. In contrast, long exposure times and high plasma powers completely oxidize the precursor to form Co3O4, reduce the carbon impurity incorporation, and improve the film crystallinity. While the resulting Co3O4 films are highly stable under electrochemical conditions, they are characterized by low oxygen evolution reaction activities. To overcome these competing properties, we applied the established relation between deposition parameters and functional film properties to design bilayer films exhibiting simultaneously improved electrochemical performance and chemical stability. The resulting biphasic films combine a highly active Co(OH)2 surface with a stable Co3O4 interface layer. In addition, these coatings exhibit minimal light absorption, thus rendering them well suited as protective catalytic layers on semiconductor light absorbers for application in photoelectrochemical devices.

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Investigation on Transparent, Conductive ZnO:Al Films Deposited by Atomic Layer Deposition Process

Nanomaterials ◽

10.3390/nano12010172 ◽

2022 ◽

Vol 12 (1) ◽

pp. 172

Author(s):

Kai Zhao ◽

Jingye Xie ◽

Yudi Zhao ◽

Dedong Han ◽

Yi Wang ◽

...

Keyword(s):

Atomic Layer Deposition ◽

High Performance ◽

Atomic Layer ◽

Deposition Process ◽

Transparent Electrodes ◽

Al Doping ◽

Film Properties ◽

Layer Deposition ◽

System Method ◽

Current Conduction

Transparent electrodes are a core component for transparent electron devices, photoelectric devices, and advanced displays. In this work, we fabricate fully-transparent, highly-conductive Al-doped ZnO (AZO) films using an atomic layer deposition (ALD) system method of repeatedly stacking ZnO and Al2O3 layers. The influences of Al cycle ratio (0, 2, 3, and 4%) on optical property, conductivity, crystallinity, surface morphology, and material components of the AZO films are examined, and current conduction mechanisms of the AZO films are analyzed. We found that Al doping increases electron concentration and optical bandgap width, allowing the AZO films to excellently combine low resistivity with high transmittance. Besides, Al doping induces preferred-growth-orientation transition from (002) to (100), which improves surface property and enhances current conduction across the AZO films. Interestingly, the AZO films with an Al cycle ratio of 3% show preferable film properties. Transparent ZnO thin film transistors (TFTs) with AZO electrodes are fabricated, and the ZnO TFTs exhibit superior transparency and high performance. This work accelerates the practical application of the ALD process in fabricating transparent electrodes.

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Chemical Solution Deposition of La-Substituted BiFe0.5Sc0.5O3 Perovskite Thin Films on Different Substrates

Coatings ◽

10.3390/coatings11030307 ◽

2021 ◽

Vol 11 (3) ◽

pp. 307

Author(s):

Diana Griesiute ◽

Dovydas Karoblis ◽

Lina Mikoliunaite ◽

Aleksej Zarkov ◽

Andrei N. Salak ◽

...

Keyword(s):

Thin Films ◽

Chemical Solution Deposition ◽

Cost Effective ◽

Deposition Process ◽

Stability Study ◽

Fused Silica ◽

Chemical Solution ◽

Solution Deposition ◽

Optimal Annealing Temperature ◽

Xrd Patterns

In the present work, polycrystalline Bi0.67La0.33Fe0.5Sc0.5O3 thin films were synthesized using a simple and cost-effective chemical solution deposition process employing the spin coating technique. In order to check the feasibility of the fabrication of thin films on various types of substrates, the films were deposited on Pt-coated silicon, silicon, sapphire, corundum, fused silica and glass. Based on the results of thermogravimetric analysis of precursor and thermal stability study, it was determined that the optimal annealing temperature for the formation of perovskite structure is 600 °C. It was observed that the relative intensity of the pseudocubic peaks (001)p and (011)p in the XRD patterns is influenced by the nature of substrates, suggesting that the formed crystallites have some preferred orientation. Roughness of the films was determined to be dependent on the nature of the substrate.

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Design of Molecular Water Oxidation Catalysts Stabilized by Ultrathin Inorganic Overlayers—Is Active Site Protection Necessary?

Inorganics ◽

10.3390/inorganics6040105 ◽

2018 ◽

Vol 6 (4) ◽

pp. 105 ◽

Cited By ~ 5

Author(s):

Laurent Sévery ◽

Sebastian Siol ◽

S. Tilley

Keyword(s):

Water Oxidation ◽

Atomic Layer ◽

Deposition Process ◽

Operating Conditions ◽

Molecular Water ◽

Side Reactions ◽

Aqueous Environment ◽

Oxidation Catalysts ◽

Initial Onset ◽

Anchoring Groups

Anchored molecular catalysts provide a good step towards bridging the gap between homogeneous and heterogeneous catalysis. However, applications in an aqueous environment pose a serious challenge to anchoring groups in terms of stability. Ultrathin overlayers embedding these catalysts on the surface using atomic layer deposition (ALD) are an elegant solution to tackle the anchoring group instability. The propensity of ALD precursors to react with water leads to the question whether molecules containing aqua ligands, such as most water oxidation complexes, can be protected without side reactions and deactivation during the deposition process. We synthesized two iridium and two ruthenium-based water oxidation catalysts, which contained an aqua ligand (Ir–OH2 and Ru–OH2) or a chloride (Ir–Cl and Ru–Cl) that served as a protecting group for the former. Using a ligand exchange reaction on the anchored and partially embedded Ru–Cl, the optimal overlayer thickness was determined to be 1.6 nm. An electrochemical test of the protected catalysts on meso-ITO showed different behaviors for the Ru and the Ir catalysts. The former showed no onset difference between protected and non-protected versions, but limited stability. Ir–Cl displayed excellent stability, whilst the unprotected catalyst Ir–OH2 showed a later initial onset. Self-regeneration of the catalytic activity of Ir–OH2 under operating conditions was observed. We propose chloride ligands as generally applicable protecting groups for catalysts that are to be stabilized on surfaces using ALD.

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Hafnium Zirconium Oxide Thin Films for CMOS Compatible Pyroelectric Infrared Sensors

Engineering Proceedings ◽

10.3390/i3s2021dresden-10138 ◽

2021 ◽

Vol 6 (1) ◽

pp. 27

Author(s):

Clemens Mart ◽

Malte Czernohorsky ◽

Kati Kühnel ◽

Wenke Weinreich

Keyword(s):

Thin Films ◽

Lead Zirconate Titanate ◽

Cost Effective ◽

Atomic Layer ◽

Lead Zirconate ◽

Temperature Oscillation ◽

Current Profile ◽

Infrared Sensors ◽

Integrated Sensor ◽

Ferroelectric Hysteresis

Pyroelectric infrared sensors are often based on lead-containing materials, which are harmful to the environment and subject to governmental restrictions. Ferroelectric Hf1−xZrxO2 thin films offer an environmentally friendly alternative. Additionally, CMOS integration allows for integrated sensor circuits, enabling scalable and cost-effective applications. In this work, we demonstrate the deposition of pyroelectric thin films on area-enhanced structured substrates via thermal atomic layer deposition. Scanning electron microscopy indicates a conformal deposition of the pyroelectric film in the holes with a diameter of 500 nm and a depth of 8 μm. By using TiN electrodes and photolithography, capacitor structures are formed, which are contacted via the electrically conductive substrate. Ferroelectric hysteresis measurements indicate a sizable remanent polarization of up to 331 μC cm−2, which corresponds to an area increase of up to 15 by the nanostructured substrate. For pyroelectric analysis, a sinusoidal temperature oscillation is applied to the sample. Simultaneously, the pyroelectric current is monitored. By assessing the phase of the measured current profile, the pyroelectric origin of the signal is confirmed. The devices show sizable pyroelectric coefficients of −475 μC m−2 K−1, which is larger than that of lead zirconate titanate (PZT). Based on the experimental evidence, we propose Hf1−xZrxO2 as a promising material for future pyroelectric applications.

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Improving atomic layer deposition process through reactor scale simulation

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2014.07.079 ◽

2014 ◽

Vol 78 ◽

pp. 1243-1253 ◽

Cited By ~ 14

Author(s):

Mohammad Reza Shaeri ◽

Tien-Chien Jen ◽

Chris Yingchun Yuan

Keyword(s):

Atomic Layer Deposition ◽

Atomic Layer ◽

Deposition Process ◽

Atomic Layer Deposition Process ◽

Layer Deposition

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Electrophoretic Deposition of 10B Nano/Micro Particles in Deep Silicon Trenches for the Fabrication of Solid State Thermal Neutron Detectors

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156418400025 ◽

2018 ◽

Vol 27 (01n02) ◽

pp. 1840002 ◽

Cited By ~ 1

Author(s):

Machhindra Koirala ◽

Jia Woei Wu ◽

Adam Weltz ◽

Rajendra Dahal ◽

Yaron Danon ◽

...

Keyword(s):

Solid State ◽

Thermal Neutron ◽

Electrophoretic Deposition ◽

Detection Efficiency ◽

Chemical Vapor ◽

Cost Effective ◽

Deposition Process ◽

Neutron Detectors ◽

Micro Particles ◽

Silicon Trenches

We present a cost effective and scalable approach to fabricate solid state thermal neutron detectors. Electrophoretic deposition technique is used to fill deep silicon trenches with 10B nanoparticles instead of conventional chemical vapor deposition process. Deep silicon trenches with width of 5-6 μm and depth of 60-65 μm were fabricated in a p-type Si (110) wafer using wet chemical etching method instead of DRIE method. These silicon trenches were converted into continuous p-n junction by the standard phosphorus diffusion process. 10B micro/nano particle suspension in ethyl alcohol was used for electrophoretic deposition of particles in deep trenches and iodine was used to change the zeta potential of the particles. The measured effective boron nanoparticles density inside the trenches was estimated to be 0.7 gm cm-3. Under the self-biased condition, the fabricated device showed the intrinsic thermal neutron detection efficiency of 20.9% for a 2.5 × 2.5 mm2 device area.

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Growth Mechanism and Film Properties in Pulsed Laser-Plasma Deposition

MRS Proceedings ◽

10.1557/proc-236-417 ◽

1991 ◽

Vol 236 ◽

Author(s):

S. Metev ◽

K. Meteva

Keyword(s):

Laser Plasma ◽

Growth Process ◽

Plasma Deposition ◽

Pulsed Laser ◽

Deposition Process ◽

Experimental Investigations ◽

Direct Relation ◽

Film Properties ◽

Experimental Conditions ◽

Laser Flux

AbstractIn the paper the results of a theoretical investigation of the growth process of laser-plasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density, substrate temperature) and film properties (thickness, structure). The results of some experimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical model.

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