Ruthenium Oxide Electrodes Research Articles

(Keynote) Competition of Oxygen and Chlorine Evolution on Oxide Surfaces – a Soft X-Ray and Dems Approach to Identification of Active Site

Anodic gas evolving reactions, e.g. oxygen evolution and chlorine evolution, are of fundamental importance both in energy storage as well as in electrolytic production of chemicals. Both reactions are of electrocatalytic nature, proceed in the same potential range and are catalyzed by the same types of electrode materials. While the oxygen evolution is thermodynamically favored the two electron chlorine evolution is kinetically preferred, namely at acid and neutral pH. This kinetic preference is industrially explored in chlor-alkali processes as well in chlorate electrolysis. The growing interest in electrolytic hydrogen production fueled by the popularity of the hydrogen as the likely replacement of fossil fuels brings up the question of the tolerance of the industrial anodes to presence of chlorides in the water intended for electrolytic hydrogen production. Such a tolerance can be best achieved by steering the selectivity of the anode between oxygen and chlorine evolution aiming eventually at the possibility of the sea water use in hydrogen producing water electrolysis. So far existing attempts at control the anode selectivity in presence of chlorides explore two principal approaches – pH control and surface engineering. While the pH related approach is rationalized by different pH sensitivity of each of the competing reaction the surface engineering related activities so far rely on trial and error approach. Qualitatively the selectivity may be controlled by either selectively promoting/suppressing each of the contributing reactions. While the literature lists attempts when the overall selectivity towards OER is apparently achieved by selective suppression of CER [1] more recent reports suggest that the actual selectivity is in fact controlled by the ability of the catalysts to support a lattice oxygen activating mechanism of the oxygen evolution process [2]. While these assignments are based on correlation of selectivity measurements with local structure and DFT modelling and a direct evidence of such a behavior is so far missing. This paper will document here the capability of the real-time and operando soft X-ray absorption spectroscopy [3] to provide this missing evidence. Anodic behavior of two type of ruthenium oxide electrodes in chloride free and chloride containing solutions will be documented by comparison of the nature and potential dependent population of the oxygen related intermediates formed at anode surface in the potential range of oxygen and chlorine evolution in acid media (pH=1) and combined with DEMS data to identify the active sites for each contributing electrode reaction.

Electrochemical Properties of Sputtered Ruthenium Oxide Neural Stimulation and Recording Electrodes

A chronically stable electrode material with a low impedance for recording neural activity, and a high charge-injection capacity for functional electro-stimulation is desirable for the fabrication of implantable microelectrode arrays that aim to restore impaired or lost neurological functions in humans. For this purpose, we have investigated the electrochemical properties of sputtered ruthenium oxide (RuOx) electrode coatings deposited on planar microelectrode arrays, using an inorganic model of interstitial fluid (model-ISF) at 37 °C as the electrolyte. Through a combination of cyclic voltammetry (CV) and an electrochemical impedance spectroscopy (EIS) modelling study, we have established the contribution of the faradaic reaction as the major charge-injection contributor within the safe neural stimulation potential window of ±0.6 V vs. Ag|AgCl. We have also established the reversibility of the charge-injection process for sputtered RuOx film, by applying constant charge-per-phase current stimulations at different pulse widths, and by comparing the magnitudes of the leading and trailing access voltages during voltage transient measurements. Finally, the impedance of the sputtered RuOx film was found to be reasonably comparable in both its oxidized and reduced states, although the electronic contribution from the capacitive double-layer was found to be slightly higher for the completely oxidized film around 0.6 V than for its reduced counterpart around −0.6 V.

Electrochemical Analysis of Magnesium Orotate Tautomers

The oxide-ruthenium electrode is used for the analysis of oxygen-containing biologically active organic substances. This electrode can be recommended for the analysis of formic acid in dilute solutions (no more than 2 ml in 100 ml of solution). Due to the presence of two display potentials, the reliability of the determination of formic acid in solution is quite high. For the determination of nitrogen-containing compounds (urea), oxide-ruthenium electrodes are unsuitable. The obvious differences in the polarization curves of magnesium orotate tautomers indicate that the structural differences of tautomers persist in aqueous solutions. An electrochemical method using a ruthenium oxide electrode can be recommended for the analysis of the isomeric state of organic compounds containing OH and COOH groups. The electrochemical method has clearly shown that the difference in the structural state of magnesium orotate tautomers persists in solutions.

Easy and Support-Free Synthesis of Bimetallic Borates for Boosting the Oxygen Evolution Reaction

The sluggish kinetics of the oxygen evolution reaction (OER) is one of the most limiting factors for the development of many “green” electrochemical devices. Expensive ruthenium and iridium oxide electrodes are often used as advanced electrocatalysts to overcome this limitation. However, these materials are rare in nature, which further limit the implementation of this kind of electrochemical device on a global scale. Compounds based on transition metals and boron have proven to be promising alternatives to commercial electrocatalysts due to their high catalytic properties and robust stability under working conditions. However, such compounds are often obtained through expensive synthetic routes that often involve the use of supports, which increases the cost of electrocatalysts. Here, we present an easy and support-free synthesis of bimetallic borates based on the introduction of transition metals into cobalt borates. Depending on the metal, different morphologies, structural order, surface chemistry, and, most importantly, electrocatalytic properties toward the OER have been obtained. Among all the transition metals, nickel is the one that most improves the catalytic activity of cobalt borate for the OER in an alkaline electrolyte. An overpotential of 230 mV, similar to that of commercial and state-of-the-art electrocatalysts, was obtained by using a support-free synthesis route for the preparation of this catalyst.

Galvanic replacement of Pt by Cu to synthesize highly active and durable Pt@Cu/C anode as oxygen evolution reaction catalyst

In this research, a two-step procedure was applied to prepare Pt/Cu/C titanium-supported anode as an oxygen evolution reaction (OER) catalyst. First, the copper nanoparticles with an average particle size of 20 nm were chemically reduced on carbon Vulcan powder (Cu/C). Then, galvanic replacement of Pt by Cu was performed by immersing Cu/C powder in a platinum solution. Finally, the catalyst ink was brushed over the activated titanium substrate using Pt/Cu/C powder and polyvinylidene difluoride (PVDF) in N-methyl-2-pyrrolidone (NMP) solvent. The effect of different factors, such as synthesis temperature and platinum loading on the catalytic properties of nanoparticles, including electrochemical surface area (ECSA), activity, stability, and durability for the OER, were evaluated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and consecutive CV. The results showed that the platinum loading level of 0.5 mg/cm2 and the synthesis temperature of 60 °C provide the best catalytic performance. Also, compared to the commercial electrodes of iridium oxide and ruthenium oxide with the same noble metal loading, higher activity is obtained for Pt/Cu/C electrode than the two mentioned electrodes. In addition, from a lifetime standpoint, the Pt/Cu/C electrode showed higher stability than the commercial ruthenium oxide electrode.

Charge injection characteristics of sputtered ruthenium oxide electrodes for neural stimulation and recording.

We have studied the charge-injection characteristics and electrochemical impedance of sputtered ruthenium oxide (RuOx ) films as electrode coatings for neural stimulation and recording electrodes. RuOx films were deposited by reactive DC magnetron sputtering, using a combination of water vapor and oxygen gas as reactive plasma constituents. The cathodal charge storage capacity of planar RuOx electrodes was found to be 54.6 ± 9.5mC/cm2 (mean ± SD, n=12), and the charge-injection capacity in a 0.2-ms cathodal current pulse was found to be 7.1 ± 0.3mC/cm2 (mean ± SD, n=15) at 0.6V positive bias versus Ag|AgCl, in phosphate buffer saline at room temperature for ~250 nm thick films. In general, the RuOx films exhibited high charge-injection capacities, with or without a positive interpulse bias, comparable to sputtered iridium oxide (SIROF) coatings. The charge-injection capacity increased monotonically with film thickness from 120 to 630 nm, and reached 11.30 ± 0.34 mC/cm2 (mean ± SD, n=5) at 0.6V bias versus Ag|AgCl at 630 nm film thickness. In addition, RuOx films showed minimal changes in electrochemical characteristics over 1.5 billion cycles of constant current pulsing at a charge density of 408 μC/cm2 (8nC/phase, 200 μs pulse width). The findings of low-impedance, high charge-injection capacity, and long-term pulsing stability suggest the suitability of RuOx as a comparatively inexpensive and favorable choice of electrode material for neural stimulation and recording.

Controlling of RuO2 Nanostructures by Deposition Temperature and Its Effect on Structural, Morphological and Electrochemical Properties

Nanostructured ruthenium oxide electrodes materials were synthesized on stainless steel substrate at 473 K–773 K temperatures with 100 K intervals using automatic spray pyrolysis technique via an aqueous route. The physical and supercapacitive properties of the deposited electrodes were characterized thoroughly. Deposited electrodes show an amorphous structural property. Electrodes deposited at various temperature shows various morphologies such as rough porous interconnected pattern like granular morphology and well-covered dense sheet-like morphology. Electrode deposited at 673 K shows superior electrochemical properties viz highest specific capacitance of 524.9 F g−1 at 5 mV s−1, specific energy 128.2 Wh kg−1, specific power 256 kW kg−1, and columbic efficiency 94% in 1 M H2SO4 electrolyte. Electrochemical impedance spectroscopy reveals the capacitive behavior of the electrode. Electrode shows 3.39Ω combined internal resistance. Overall results demonstrate that spray deposited RuO2 at 673 K can be excellent electrode material for next-generation energy storage applications.

Process Optimization of Waste Activated Sludge in Anaerobic Digestion and Biogas Production by Electrochemical Pre-Treatment Using Ruthenium Oxide Coated Titanium Electrodes

Anaerobic digestion (AD) appears to be a popular unit operation in wastewater treatment plant to treat waste activated sludge (WAS) and the produced methane gas can be harvested as renewable energy. However, WAS could inhibit hydrolysis stage during AD and hence pre-treatment is required to overcome the issue. This paper aimed to study the effect of electrochemical pre-treatment (EP) towards efficiency of AD using titanium coated with ruthenium oxide (Ti/RuO2) electrodes. The investigation has been carried out using in-house laboratory batch-scale mesophilic anaerobic digester, mixed under manipulation of important operating parameters. Optimization was performed on EP using response surface methodology and central composite design to maximize sludge disintegration and dewaterability. By operating at optimal conditions (pH 11.65, total solids 22,000 mg/L, electrolysis time 35 min, current density 6 mA/cm2, and 1000 mg/L of sodium chloride), the pre-treated WAS in terms of mixed liquor volatile suspended solids (MLVSS) removal, soluble chemical oxygen demand (sCOD), capillary suction time (CST) reduction, and extracellular polymeric substance (EPS) were 38%, 4800 mg/L (increased from 935 mg/L), 33%, and 218 mg/L, respectively. Following AD, the volatile solids (VS) removal and chemical oxygen demand (COD) removal by EP were enhanced from 40.7% and 54.7% to 47.2% and 61.5%, respectively, at steady-state. The biogas produced from control and electrochemical pre-treated WAS were in the ranges of 0.12 to 0.17 and 0.2 to 0.24 m3/kg VSfed, respectively, and the volume of biogas produced was 44–67% over the control. Based on the results obtained, suitability of EP for WAS prior to AD was confirmed.

Monitoring Contractile Cardiomyocytes via Impedance Using Multipurpose Thin Film Ruthenium Oxide Electrodes.

A ruthenium oxide (RuOx) electrode was used to monitor contractile events of human pluripotent stem cells-derived cardiomyocytes (hPSC-CMs) through electrical impedance spectroscopy (EIS). Using RuOx electrodes presents an advantage over standard thin film Pt electrodes because the RuOx electrodes can also be used as electrochemical sensor for pH, O2, and nitric oxide, providing multisensory functionality with the same electrode. First, the EIS signal was validated in an optically transparent well-plate setup using Pt wire electrodes. This way, visual data could be recorded simultaneously. Frequency analyses of both EIS and the visual data revealed almost identical frequency components. This suggests both the EIS and visual data captured the similar events of the beating of (an area of) hPSC-CMs. Similar EIS measurement was then performed using the RuOx electrode, which yielded comparable signal and periodicity. This mode of operation adds to the versatility of the RuOx electrode’s use in in vitro studies.

Measuring Both pH and O2 with a Single On-Chip Sensor in Cultures of Human Pluripotent Stem Cell-Derived Cardiomyocytes to Track Induced Changes in Cellular Metabolism

In vitro studies which focus on cellular metabolism can benefit from time-resolved readouts from the living cells. pH and O2 concentration are fundamental parameters upon which cellular metabolism is often inferred. This work demonstrates a novel use of a ruthenium oxide (RuOx) electrode for in vitro studies. The RuOx electrode was characterized to measure both pH and O2 using two different modes. When operated potentiometrically, continuous pH reading can be obtained, and O2 concentration can be measured chronoamperometrically. In this work, we demonstrate the use of the RuOx electrodes in inferring two different types of metabolism of human pluripotent stem cell-derived cardiomyocytes. We also show and discuss the interpretation of the measurements into meaningful extracellular acidification rates and oxygen consumption rates of the cells. Overall, we present the RuOx electrode as a versatile and powerful tool in in vitro cell metabolism studies, especially in comparative settings.

Creating electronic and ionic conductivity gradients for improving energy storage performance of ruthenium oxide electrodes

Robust Ru-based thin films are successfully fabricated by single- (SA) and multiple-annealing (MA) thermal decomposition methods and are utilized as high-performance electrodes for the supercapacitors. Two critical parameters, the annealing temperature and treatment duration, are engineered for synthesizing stable thin-film electrodes. It is found that the SA thermal decomposition technique at 250 °C for 6 h results in stable RuO2 electrodes with remarkable electrochemical performance. The MA approach consists of 2- and 3-stage thermal treatment steps. The maximal capacitance of MA-treated capacitor reaches as high as 308.8 F g−1. The MA-treated electrodes deliver exceptional rate capability as well as superior cycling stability (93% capacitance retention upon 2000 cycles). The enhanced performance is attributed to the multistep thermal stages along with the layer-by-layer deposition, enabling enhanced heat transfer to individual thin layers. An optimal thermal treatment procedure is assessed empowering enhanced capacitive performance due to high hydrous RuO2·xH2O ratio, reduced crystalline structure, facile electrolyte wetting, and stable adhesion between the deposits and the Ti substrate. The robust design of MA-treated thin film deposits paves the way for synthesizing high-performance electrodes for the supercapacitors.

Sputtered ruthenium oxide coatings for neural stimulation and recording electrodes.

We have investigated the deposition and electrochemical properties of sputtered ruthenium oxide coatings for neural stimulation and recording electrodes. A combination of oxygen and water vapor was used as a reactive gas mixture during DC magnetron sputtering from a ruthenium metal target. The sputtering plasma was monitored by optical emission spectroscopy to determine the reactive species present and confirm the control of plasma chemistry by reactive gas flow rates into the deposition chamber. The effect of the O2 :H2 O gas ratio on the microstructure and electrochemical properties of the ruthenium oxide were studied in detail. We employed a combination of surface characterization techniques, including scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy, to understand the relationship between plasma chemistry and the microstructure of the films produced under different gas flow conditions. Electrochemical characterization included cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transient measurements, performed on planar ruthenium oxide electrodes with a geometric surface area of 1960 μm2 . At an O2 :H2 O gas flow rate ratio of 1:3, a cathodal charge-storage capacity per unit film thickness of 228.7 mC cm-2 μm-1 (median, Q1 = 134.5, Q3 = 236.6, n = 15) and a charge-injection capacity (0.6 V anodal interpulse bias) of 7.4 mC cm-2 (median, Q1 = 6.9, Q3 = 8.3, n = 15) were obtained in phosphate buffered saline. The charge-injection capacity of ruthenium oxide sputtered with water vapor in the reactive plasma is comparable with sputtered iridium oxide (SIROF) and higher than reported values for porous TiN, a commonly employed high-surface area stimulation electrode coating.

Graphene induced crystallinity and hydrous state variations of ruthenium oxide electrodes for superior energy storage performance

This work adopts a thermal decomposition (TD) method for fabricating electrochemically exfoliated graphene (ECG)-modified ruthenium oxide thin film as the electrode material for high-performance supercapacitors. The TD technique consists of three consecutive thermal annealing steps for layer-by-layer coating of RuO2/ECG on the Ti substrate. We have demonstrated that the ECG content is the key factor influencing the electrochemical performance of the composite electrodes. The introduction of an appropriate amount of ECG within the composites facilitates the utilization of RuO2 and enables high capacitance, low charge transfer resistance, high rate capability, and superior durability. An optimal ECG content (5 wt.%) mixed with deposited RuO2 forms a three-dimensional conductive framework, capable of offering a synergistic effect for enhanced charge transfer as well as fast ionic diffusion. The specific capacitance of the RuO2/ECG electrode reaches as high as 407 F g−1 while maintaining the high capacitance (> 97%) during prolonged cycling (2000 cycles). The Ragone plot confirms that the RuO2/ECG capacitor enables a high energy density of 10.2 Wh kg−1 while delivering a remarkable power density of 9.2 kW kg−1. The RuO2/ECG composite developed in this work paves the way for designing robust electrode materials for high-performance supercapacitors.

Light-Driven Electrochemical Carbon Dioxide Reduction to Carbon Monoxide and Methane Using Perovskite Photovoltaics

Summary Storing solar energy in chemical bonds is an effective strategy to overcome the intermittency of sunlight as an energy source. Here, we demonstrate unassisted light-driven electrochemical aqueous carbon dioxide reduction to carbon monoxide and methane using p-i-n double-cation lead halide perovskite solar cells in combination with catalytic electrodes for carbon dioxide reduction and water oxidation at near-neutral pH. Three series-connected photovoltaic cells and gold and ruthenium(IV) oxide electrodes provide carbon monoxide with >8% solar-to-carbon monoxide conversion efficiency for 4.5 h. Including concomitant hydrogen formation, the total solar-to-fuel conversion efficiency remains >8.3% for 10 h. Four series-connected cells with copper and ruthenium(IV) oxide electrodes provide methane. The longevity of the copper electrode improves by setting the cell to open circuit for 1 min every 15 min. The solar-to-methane conversion efficiency is close to 2%, and including 3% solar-to-hydrogen conversion efficiency, the solar-to-fuel conversion efficiency is 5% for 8 h.

Maximized Energy Density of RuO2//RuO2 Supercapacitors through Potential Dependence of Specific Capacitance

AbstractIn this study, a stepwise cyclic voltammetry approach was proposed to clarify the potential dependence of specific capacitance for reduced graphene oxide and ruthenium oxide electrodes. Based on the relationship between specific capacitance and potential, the working voltage window and energy density of RuO2//RuO2 supercapacitors (SCs) were maximized by modulating the mass ratio. The working voltage window of RuO2//RuO2 with a mass ratio of 2.03 (close to optimum mass ratio ) was extended by about 188 % when compared to that calculated at a mass ratio of 0.56. The former was equivalent to a 304 % increase in energy density. In addition, the source of wasted potential window of electrodes on RuO2//RuO2 was investigated in an effort to design and produce better SCs.

Charge Density and Charge Delivery Characteristics of Sputtered Transition Metal Oxide Films Used As Neural Stimulation and Recording Electrodes

The use of microelectronic devices for electrical stimulation and recording of neural electrical activity is a rapidly emerging technique that intends to restore lost or impaired physiological function in humans, such as spinal cord injury, stroke, sensory deficits and neurological disorders. The electrode material is one the most important components of such devices as it constituents the chronic electrode-electrolyte interface to the physiological environment. Therefore understanding the electrochemical properties of the electrodes is essential to provide electrical stimulation without adversely affecting the surrounding tissue. In this study, we explore the charge delivery mechanism of two transition metal oxides namely, iridium oxide (IrOx) and ruthenium oxide (RuOx) electrodes, systematically sputtered using water vapor as one of the reactive plasma constituents in addition to oxygen and argon. Additionally, we examine the effect of microstructure controlled by the composition of the reactive plasma constituents, on electrochemistry and charge density characteristics. Electrode sites with a geometric surface area (GSA) of 1960 μm2 were fabricated on silicon wafers using photolithography to create conductive gold metallization to define contact pads, electrode sites, and interconnect traces. The electrode sites were coated with sputtered IrOx and RuOx films using DC magnetron sputtering with a range of reactive gas ratios (O2:H2O) in the plasma. Material characterization techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to study the microstructure and composition of the electrode coatings. Electrochemical analysis included open circuit potential (Eoc) measurements, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and voltage transient (VT) measurements in electrolyte solutions that mimic the inorganic constituents of the physiological environment. Charge storage capacity (CSC) as a function of sweep and charge injection capacity (Qinj) as a function of pulse width and interpulse bias where calculated from the CV and VT measurements. Varying the plasma constituents show a systematic change in the morphology of both the IrOx and RuOx films. The magnitudes of CSC and Qinj also have a systematic dependence on the morphology of the films as controlled by the composition of the sputtering gases. Figure 1(a) shows a representative dependence of morphology and Qinj as a function of plasma composition for IrOx deposition with similar results obtained for RuOx films. The Eoc of the films was measured as a function of pH, as shown in figure 1(b), with IrOx and RuOx showing a near-Nernstian 62 mV/pH-unit and 59 mV/pH-unit, respectively. In this study, we demonstrate the dependence of IrOx and RuOx film morphology on the composition of the reactive plasma constituents. The relationship between film microstructure and electrochemistry at near-neutral pH has been investigated and the charge delivery mechanisms of sputtered IrOx and RuOx films characterized. The addition of water vapor as a reactive gas constituent increased the charge injection capacity of both IrOx and RuOx films using typical neural stimulation waveforms. Figure 1

Pulse electrodeposited RuO2 electrodes for high-performance supercapacitor applications

ABSTRACTThe present work addresses high-performance Ruthenium Oxide (RuO2) electrodes prepared by using a simple pulse electrodeposition method. For the comparison purpose, two different precursors, namely, ruthenium (III) nitrosyl sulphate (RuNS) and ruthenium trichloride (RuCl3), were used in this study. The coatings were subjected to material characterisation such as Field Emission Scanning Electron Microscopy and Energy-Dispersive X-ray Spectroscopy, X-ray diffraction and Transmission electron microscopy as well as electrochemical characterisation such as Cyclic Voltammetry, Electrochemical Impedance Spectroscopy and charge/discharge. The RuNS–RuO2 coating exhibited excellent specific capacitance (1724 F/g at 5 A/g) with a remarkable rate capability. This value is significantly higher (52%) than the value obtained for RuCl3–RuO2 electrode material at 5 A/g. The findings provide valuable information on the potential use of RuNS as a precursor for synthesising RuO2 and pulse electrodeposition process to produce electrodes for supercapacitors.

Accurate Modulation of Mass Ratio on Electrodes of Ruthenium Oxide//Polyaniline Supercapacitor for Improving Energy Density

Polyaniline and ruthenium oxide electrodes are prepared to assemble the supercapacitors. The electrochemical properties of the electrodes are studied by cyclic voltammetry and galvanostatic charging/discharging measurements. The potential dependence of specific capacitance for the electrodes in the supercapacitors is established. Based on the relationship between specific capacitance and potential of electrodes, the optimum mass ratio of the electrodes in asymmetric supercapacitor of ruthenium oxide//polyaniline can be accurately determined. The working voltage window for ruthenium oxide//polyaniline supercapacitor is significantly increased by the modulation of mass ratio. Accordingly, the electrical energy density of supercapacitor with a mass ratio of = 0.79 is as high as 7.25 Wh kg−1, about 314% higher than that of the supercapacitor with a mass ratio of 0.26.

Effect of electrodeposition modes on ruthenium oxide electrodes for supercapacitors

With developments in energy storage devices, supercapacitors are gaining more attraction because of their potential to excel batteries shortly. In this work, ruthenium oxide (RuO2) has been deposited on stainless steel and studied the influence of surface modification of solid electrodes on capacitance properties. Hydrous ruthenium oxide was plated by different modes such as potential sweep method (cyclic voltammetric), constant potential method (chronoamperometry) and optimised potential pulse method using a recently reported precursor material namely ruthenium nitrosylsulfate (RuNS). The structural information and morphology of electrodeposits were characterised by X-ray diffractometer and scanning electron microscope respectively. The XRD studies indicate a poor crystalline state for RuO2 in all the modes of deposition but can contribute to a higher surface area when compared to a highly crystalline form. The SEM analysis revealed the formation of surface modification concerning the change of potential mode. Mud-cracked morphology, spherical particles and dendrimeric morphology observed on chronoamperometry, potential pulse and cyclic voltammetry respectively. Electrochemical studies were also conducted on the samples to assess their performance for supercapacitor applications. The spherical particles of hydrous RuO2 show high performance of capacitance behaviour 1180 F/g in 0.5 M H2SO4 at the scan rate of 5 mV/s. Dendrimeric morphology and mud-cracked morphology shows 573 F/g and 546 F/g respectively in same 0.5 M H2SO4 at the scan rate of 5 mV/s. The studies reveal that RuO2 electrodes can be exploited for their outstanding capacitive behaviour by properly controlling the morphology of the deposits.

Ultrahigh specific capacitance of spray deposited nanoporous interconnected ruthenium oxide electrode fabric for supercharged capacitor

In present work, nanoporous interconnected ruthenium oxide electrode fabric have been designed and prepared successfully by spray pyrolysis technique on thin stainless steel substrates via aqueous route. X-ray diffraction analysis gives amorphous nature of the prepared sample. The existence of non-covalent interactions between ruthenium and oxygen was confirmed by Fourier transform infrared spectroscopy. The elemental analysis was observed by using elemental dispersive spectrum and X-ray photoelectron spectroscopy. Morphological analysis of the ruthenium oxide fabric revealed the nanoporous granular interconnected architecture, producing high specific surface area and good electronic or ionic conducing path. The use of nanoporous interconnected ruthenium oxide electrode fabric is as free-standing electrodes for supercharged capacitor, which offers excellent ability of ultrahigh specific capacitance 1429 F g−1 at scan rate 1 mV s−1, higher energy density 172 Wh kg−1, power density 320 KW kg−1 and columbic efficiency is 94.74% in 1 M KOH. Also it exhibits very low charge transfer resistance (0.89 Ω) and relatively excellent cycle stability at scan rate 100 mV s−1 for 3000 cycles, which concluded that it has a potential application as a supercharged capacitor electrode fabric.