Ruthenium Oxide Films Research Articles

Anodic deposition of hydrous ruthenium oxide for supercapaciors: Effects of the AcO − concentration, plating temperature, and oxide loading

Effects of the sodium acetate (NaCH 3COO, denoted as NaAcO) concentration, plating temperature, and oxide loading on the pseudocapacitive characteristics of hydrous ruthenium oxide (denoted as RuO 2· xH 2O) films anodically plated from aqueous RuCl 3· xH 2O media were systematically investigated in this work. The electrochemical behavior of RuO 2· xH 2O with annealing in air at 200 °C for 2 h is approximately independent of the NaAcO concentration and plating temperature although a negative shift in the onset and peak potentials of deposition with rising the plating temperature is found. The morphologies and adhesion of RuO 2· xH 2O deposits strongly depend on the deposition rate which is obviously influenced by varying the above two deposition variables. The specific capacitance of RuO 2· xH 2O is monotonously decreased from 760 to 505 F g −1 when the oxide loading is gradually increased from 0.34 to 1.0 mg cm −2, due to the longer pathways of both electrons and protons during the redox transitions. The XRD and Raman spectroscopic analyses reveal the extremely localized crystalline nature of as-deposited RuO 2· xH 2O. All RuO 2· xH 2O deposits show the ideal pseudocapacitive characteristics, definitely illustrating the merits of RuO 2· xH 2O prepared by anodic deposition without considering the advantages of its simplicity, one-step, reliability, low cost, and versatility for electrode preparation.

Methanol oxidation reaction on Ti/RuO 2( x) Pt (1− x) electrodes prepared by the polymeric precursor method

In this work, ruthenium oxide films containing platinum nanoparticles were prepared using the polymeric precursor method on Ti substrates with several molar ratios. This paper aims at presenting the characterization of the Pt content effect in the methanol electrochemical oxidation reaction. The films were physically characterized using X-ray diffraction and both Pt and RuO 2 (rutile) phases were observed. The mean crystallite sizes were 6 nm for Pt and 25 nm for RuO 2. The X-ray photoelectronic results indicated that on the electrodes surfaces, depending on the substrate, there was RuO 2, Ru metal and Pt metal. Besides, it was not observed the formation of PtRu alloys. The atomic force microscopy images of the films showed highly rough surfaces. A decrease in the roughness mean square values is observed as the Pt content increases. These last results are similar to electroactive surface area values calculated by redox-couple (K 4FeCN 6/K 3FeCN 6). There was an increase in the globular size observed on the electrode surface and lower particle dispersion as the Pt content is increased from 12.5 to 75 mol%. Regarding the eletrode electrocatalytical behavior for methanol oxidation, it was observed that the onset oxidation overpotential is displaced towards more negative values as Pt content is decreased. Besides, an increase has been shown in the current density for methanol oxidation of 600% using a Ti/RuO 2-Pt (87.5:12.5) electrode compared to polycrystalline Pt.

Spray deposited amorphous RuO 2 for an effective use in electrochemical supercapacitor

The structural, surface morphological and optical properties of sprayed ruthenium oxide thin film were investigated using XRD, SEM and optical absorption measurements. The structural analysis from XRD pattern showed the formation of RuO 2 in amorphous phase. The scanning electron micrographs revealed network-like morphology of ruthenium oxide. The optical studies showed a direct band gap of 2.4 eV for ruthenium oxide films. Ruthenium oxide thin film exhibited a cyclic voltammogram indicative high reversibility of a typical capacitive behavior in 0.5 M H 2SO 4 electrolyte. A specific capacitance of 551 F/g was obtained with ruthenium oxide thin film (electrode) prepared by spray pyrolysis method. The specific capacitances of 551 and 450 F/g at the scan rate of 5 and 125 mV/s, respectively, indicate that the capacitance value varies inversely with scan rate.

Ruthenium and Ruthenium Oxide Films Deposition by MOCVD Using Ru(DMPD)2

Physical properties of bis(2,4-dimethylpentadienyl) ruthenium [Ru(DMPD)2] were examined by comparing with those of (2,4- dimethylpentadienyl)(ethylcyclopentadienyl) ruthenium [Ru(DMPD) (EtCp)]. Ru(DMPD)2 had almost the same vaporizing characteristic as Ru(DMPD)(EtCp) and showed lower decomposition temperature of 210{degree sign}C than those of Ru(DMPD)(EtCp), 270{degree sign}C. Ru- based films was deposited from Ru(DMPD)2 - O2 system. Metallic Ru films were deposited at 400{degree sign}C under the oxygen concentration below 0.25%. Crystalline metallic Ru films were deposited down to 220{degree sign}C under this oxygen concentration for the first time using Ru(DMPD)2.

A nanogravimmetric investigation of the charging processes on ruthenium oxide thin films and their effect on methanol oxidation

The charging processes and methanol oxidation that occur during the oxidation–reduction cycles in a ruthenium oxide thin film electrode (deposited by the sol–gel method on Pt covered quartz crystals) were investigated by using cyclic voltammetry, chronoamperometry and electrochemical quartz crystal nanobalance techniques. The ruthenium oxide rutile phase structure was determined by X-ray diffraction analysis. The results obtained during the charging of rutile ruthenium oxide films indicate that in the anodic sweep the transition from Ru(II) to Ru(VI) occurs followed by proton de-intercalation. In the cathodic sweep, electron injection occurs followed by proton intercalation, leading to Ru(II). The proton intercalation/de-intercalation processes can be inferred from the mass/charge relationship which gives a slope close to 1gmol−1 (multiplied by the Faraday constant) corresponding to the molar mass of hydrogen. From the chronoamperometric measurements, charge and mass saturation of the RuO2 thin films was observed (440ngcm−2) during the charging processes, which is related to the total number of active sites in these films. Using the electrochemical quartz crystal nanobalance technique to study the methanol oxidation reaction at these films was possible to demonstrate that bulk oxidation occurs without the formation of strongly adsorbed intermediates such as COads, demonstrating that Pt electrodes modified by ruthenium oxide particles can be promising catalysts for the methanol oxidation as already shown in the literature.

Ruthenium and Ruthenium Oxide Films Deposition by MOCVD using Ru(DMPD)2

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Electrochemical capacitance of nanocomposite films formed by loading carbon nanotubes with ruthenium oxide

This work reports the supercapacitive properties of composite films of multiwalled carbon nanotubes (MWNT) and ruthenium oxide (RuO 2). Transmission and scanning electron microscopy, cyclic voltammetry, and electrochemical studies revealed that the nanoporous three-dimensional arrangement of RuO 2-coated MWNT in these films facilitated the improvement of electron and ion transfer relative to MWNT films. The capacitance was measured for films of different RuO 2 loading, revealing specific capacitances per mass as high as 628 F g −1. The energy storage density of the electrode has increased about three times as compared to MWNT treated with piranha solution.

Photolithographic Deposition of Ruthenium Thin Films by Photochemical Metalorganic Deposition

The photochemistry of Ru(tmhd)2(cod) (where tmhd = 2,2,6,6-tetramethyl-3,5- heptanedionate and cod = 1,5-cyclooctadiene) precursor films on Si(111) substrate was used to develop a process for the lithographic deposition of ruthenium oxide films. The photochemical reaction of Ru(tmhd)2(cod) films was monitored by FTIR. Upon exposure the coordinated ligands were lost from the film in a sequential process through an intermediate tentatively, assigned as Ru(tmhd)2 by mass spectral analysis of the material which out gassed from the film and FTIR spectroscopy. The photogenerated films were found to be amorphous ruthenium, by x-ray and electron diffraction experiments, high resolution transmission electron microscopy and Auger electron spectroscopy although, we could not rule out the possibility of some oxygen impurity. Upon annealing in air, thin films of crystalline RuO2 films with the rutile structure were produced. The use of Ru(THMD),sub>2(cod) precursor film to deposit features with 3 μm feature size by contact mask lithography is demonstrated.

Ruthenium oxide films for selective coatings

Abstract Although commercial selective surfaces are already available, investigation on different deposition methods and materials still goes on at many laboratories. In this work, ruthenium oxide films upon metallic substrates are assessed for this usage. Deposition of the films was made at room temperature by either spraying or dipping method in a ruthenium chloride alcoholic solution. After deposited on titanium substrates, the films were heat-treated at temperatures between 450 and 500 °C. When deposited on no-polished substrates, such films not only exhibit a high solar absorptance ( α ∼ 0.98 ), but also a high infrared emittance ( e ∼ 0.8 ), which yield a low selectivity ( S = α / e = 1.2 ). By deposition of similar films on polished substrates, absorptance decreases ( α ∼ 0.74 ), but emittance significantly decreases as well ( e ∼ 0.12 ), resulting in a net selectivity increase ( S ∼ 6 ). On the other hand, evaporating a thin (∼20 nm) gold film upon the surface of a coating on a no-polished substrate also improves noticeably its emittance value ( e ∼ 0.16 ) and a lower decrease in absorptance is achieved ( α ∼ 0.91 ), resulting in a selectivity increase ( S ∼ 5.7 ). These preliminary promising results indicate the high potential for using these films as solar selective coatings, but in order to optimize such selectivity values, further work to establish a close control on the deposition parameters and the substrate roughness value, should be done.

Thermally grown ruthenium oxide thin films

Thin ruthenium films were sputtered on oxidized silicon wafers and subsequently thermally oxidized in oxygen∕nitrogen or oxygen ambient in the temperature range from 400 to 700 °C. The morphological and structural properties of grown ruthenium oxide films were analyzed by atomic force microscopy, Raman spectroscopy, and x-ray diffraction, with electrical properties analyzed by van der Pauw technique and metal–oxide semiconductor (MOS) structures. Significant roughening of RuO2 was observed for prolonged oxidation in oxygen∕nitrogen atmosphere, or for short times in pure oxygen atmosphere. Raman spectroscopy revealed superior structural properties of thermally grown RuO2, in comparison to sputtered or metalorganic chemical vapor deposition RuO2 films. Thermally grown RuO2 is shown to have a work function of 5.1 eV, making it a suitable choice of metals, together with Ru (4.6 eV work function) for electrodes in complementary MOS n-channel and p-channel transistors.

RETRACTED: Cathodic electrodeposition of RuO2 thin films from Ru(III)Cl3 solution

Abstract Ruthenium oxide (RuO 2 ) films of different thicknesses have been cathodically deposited on titanium substrates under galvanostatic condition from aqueous acidic Ru(III)Cl 3 solution. The deposition conditions and structural properties of these films have been studied. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies revealed that as-deposited RuO 2 film is nanocrystalline. The scanning electron microscopy (SEM) study showed that RuO 2 film is porous and the surface morphology changes with film thickness.

Performance of supercapacitor with electrodeposited ruthenium oxide film electrodes—effect of film thickness

Abstract Thin-film ruthenium oxide electrodes are prepared by cathodic electrodeposition on a titanium substrate. Different deposition periods are used to obtain different film thicknesses. The electrodes are used to form a supercapacitor with a 0.5 M H 2 SO 4 electrolyte. The specific capacitance and charge–discharge periods are found to be dependent on the electrode thickness. A maximum specific capacitance of 788 F g −1 is achieved with an electrode thickness of 0.0014 g cm −2 . These results are explained by considering the morphological changes that take place with increasing film thickness.

Enhancement of Anodic Response for DMSO at Ruthenium Oxide Film Electrodes as a Result of Doping with Iron(III)

AbstractThe oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO2) is representative of numerous anodic oxygen‐transfer reactions of organosulfur compounds that suffer from slow kinetics at noble metal electrodes. Anodic voltammetric data for DMSO are examined at various RuO2‐film electrodes prepared by thermal deposition on titanium substrates. The response for DMSO is slightly larger at RuO2 films prepared in a flame as compared with films prepared in a furnace; however, temperature is more easily controlled in the furnace. Doping of the RuO2 films with Fe(III) further improves the sensitivity of anodic response for DMSO. Optimal response is obtained at an Fe(III)‐doped RuO2‐film electrode prepared using a deposition solution of 50 mM RuCl3 and 10 mM FeCl3 in a 1 : 1 mixture of isopropanol and 12 M HCl at an annealing temperature of 450 °C. The Levich plot (i vs. ω1/2) and Koutecky‐Levich plot (1/i vs. 1/ω1/2) of amperometric data for the oxidation of DMSO at an Fe(III)‐doped RuO2‐film electrode configured as a rotated disk are consistent with an anodic response controlled by mass‐transport processes at low rotational velocities. Flow injection data demonstrate that Fe(III)‐doped RuO2‐film electrodes exhibit detection capability for methionine and cysteine in addition to DMSO. Detection limits for 100‐μL injections of the three compounds are ca. 3.2×10−4 mM, i.e., ca. 32 pmol.

RBS and ERD study of epitaxial RuO2 films deposited on different single crystal substrates

A study of ruthenium dioxide films, deposited by an MOCVD method on Si/SiO2, Si/YSZ, LaAlO3, MgO, SrTiO3, and sapphire single crystal substrates, was performed using RBS, ERD and AFM methods with the aim to characterize the elemental composition, microstructural quality, and homogeneity of the films. The element depth distribution and thickness of the ruthenium oxide films were obtained using a simulation procedure.RuO2 films of a thickness of several hundred nanometres, keep a constant 1:2 ruthenium to oxygen atomic concentration ratio inside the layer, but they exhibit rather extensive substrate/film interface with mixed contents of elements. It is caused by an overlay of three factors—the interdiffusion of substrate and film elements, interface roughness, and surface roughness.Hydrogen content up to 18% in the subsurface region was proved by ERD. This fact can explain only partly a decrease in the ruthenium atomic concentration at the subsurface region. The other factor that plays a role is probably surface roughness.

A novel method to determine the diffusion coefficient of hydrogen ion in ruthenium oxide films

Hydrogen ion diffusion in ruthenium oxide film is of significant interest because of its importance in capacitor, sensor and catalyst applications. In this study, a method based on potential–pH response measurement was used to determine hydrogen ion diffusion in ruthenium oxide films. The drift in the potential–pH response is believed to be due to the hydrated layer, which affects hydrogen ion diffusion onto the oxide film of the pH sensor. Hydrogen ion diffusion coefficient of ruthenium oxide films obtained from this method was 6×10 −14 cm 2/ s . The unique feature of the potential–pH response method is its relatively simple experimental procedure, which eliminates complications arising from surface related effects and/or presence of hydrogen traps in membrane such as those found in the conventional permeation method.

Chemical Vapor Deposited RuOx Films : Effect of Oxygen Flow Rate

Ruthenium and ruthenium oxide films were deposited on a substrate at 355°C using a precursor and oxygen gas. The effects of the oxygen flow rate on film composition, microstructure, surface morphology, stress, and resistivity were investigated. The oxygen content in the film increases as the oxygen flow rate increases and saturates at a flow of 1200 sccm. Films deposited with an flow rate of 800 sccm or less have the structure of the ruthenium phase, a 〈001〉 texture, and smooth surface morphology. Films deposited with an flow rate of 1200 sccm or above have the structure of the ruthenium dioxide phase and higher surface roughness. Ru-phase films have a high stress level and low resistivity; the increase of oxygen flow rate from 50 to 800 sccm results in a decrease of stress from 8 to and an increase of resistivity from 19 to 48 μΩ cm. -phase films have a relatively low stress level which does not change significantly with the oxygen flow rate, and high resistivity which slightly decreases from 120 to 115 μΩ cm as the oxygen flow rate increases from 1200 to 2000 sccm. © 2002 The Electrochemical Society. All rights reserved.

Ruthenium oxide for effective activation of aluminium sacrificial anodes: a new approach

Ruthenium oxide, one of the excellent electrocatalysts having high conductivity and high chemical and thermodynamic stability, has been coated onto the surface of an electrode made from a Al–5 wt-%Zn alloy. The activated aluminium ion was able to diffuse through the porous catalytic hydrophilic layer. Ruthenium oxide coated Al–Zn alloy anodes displayed high open circuit potential and high closed circuit potential during galvanic exposure with mild steel cathodes. A galvanic efficiency as high as 86% with an actual current capacity of 2573 A h kg-1 was achieved. The RuO2 film underwent very little deterioration and a considerable mass of the ruthenium oxide film persisted on the anode surface, even after the electrode size had been reduced to one third of its original size owing to galvanic dissolution. These electrodes are economically efficient, as convenient to prepare, install and use as other conventional electrodes, are tolerable of very aggressive media and highly efficient, even under high galvanic current loads.

Chemical vapor deposition of ruthenium oxide thin films from Ru(tmhd) 3 using direct liquid injection

Direct liquid injection (DLI) of Ru(tmhd) 3 (tmhd=2,2,6,6-tetramethylheptane-3,5-dione) in n-butylacetate solvent was used to deposit ruthenium oxide and ruthenium thin films in the temperature range of 250–450 °C. Arrhenius plot showed that the mass transfer of the reactant determined the deposition rate at high temperature and it was determined by the surface reaction at lower temperature. Depending on the operating conditions, oxide phase, metal phase or mixed phase was obtained. At low O 2 flow rate and high injection rate of the precursor solution, the formation of ruthenium was preferred. For example, at the condition of the injection rate of 0.07 ml/min and O 2 flow rate of 300 sccm, ruthenium metal phase was deposited over 350 °C. At lower injection rate, ruthenium oxide films with low resistivity of approximately 45–60 μΩ cm were formed which showed dense and smooth surface morphology. At high deposition temperature, the resistivity of the film was increased due to the carbon incorporation.

Low-temperature growth of RuO 2 films for conductive electrode applications

Conductive ruthenium oxide films are considered as possible candidate for electrodes in complementary metal oxide semiconductor and random-access memory applications. We have succeeded in growth of highly conducting RuO 2 films by metal organic chemical vapour deposition on silicon substrates at deposition temperatures between 250°C and 500°C. Structural and electrical properties of the films were studied as a function of deposition temperature. Room temperature resistivity of the films increased from 40 μΩcm for the deposition temperature 500°C to above 100 μΩcm for the deposition temperature 250°C. The films prepared at temperatures below 300°C exhibit smooth surface and excellent step coverage. These films could be used in the above-mentioned applications.

Characterization of Ruthenium and Ruthenium Oxide Thin Films deposited by Chemical Vapor Deposition for CMOS Gate Electrode Applications

ABSTRACTThis study describes work carried out to date involving evaluation of the chemical, structural, and electrical performance of ruthenium (Ru) and ruthenium oxide (RuO2) films grown on SiO2 substrates employing metal organic chemical vapor deposition (MOCVD). Diethyl ruthenocene and oxygen were employed as reactant gases for this work, which was carried out using a 200mm wafer cluster tool. The films were characterized using cross-sectional scanning electron microscopy (CS-SEM), four-point resistance probe, x-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), x-ray diffraction (XRD), and energy dispersive spectrometry (EDS). Capacitance-voltage (C-V) measurements were also carried out to assess the work function of the deposited films. It was determined that both Ru and RuO2 phases possess near-bulk resistivity and low contamination levels. Importantly, it was observed that the film stoichiometry could be modulated by controlled changes of the processing conditions, and that pure Ru and RuO2 films can be deposited in an oxygen ambient. In order to assess thermal stability, the films were subsequently annealed in forming gas and oxygen ambients, and it was found that the film stability is dependent upon both the deposited phase and the annealing ambient. Results of PMOS gate electrode performance testing of CVD Ru films, has been carried out, and the results are similar to those previously reported for ruthenium-based films.