Constant Anodic Potential Research Articles

Polythiophene/graphene oxide thin films: optical properties

Thin films of polythiophene/graphene oxide (PTh/GO) were prepared using chronoamperometry. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM), UV-Vis spectroscopy, and photoluminescence spectroscopy (PL) were used for characterization purposes. PTh and PTh/GO thin films were achieved through chronoamperometry at a constant anodic potential of +1.9 V vs. Ag/AgCl. The PTh/GO thin films exhibited visible light absorption. The thicknesses of the thin films were approximately 2.42 µm.

Phenol Biodegradation by Three Bacterial Strains Stimulated by Constant Electric Field

Objective: The aim of the present study is to compare phenol biodegradation activity of bacteria from the strains Xanthobacter autotrophicus GJ 10, Pseudomonas denitrificans and Pseudomonas putida enhanced by constant electric field in a potentiostatic mode by free cultures and immobilized cells on granulated activated carbon. Theoretical Framework: The work is based on the concept of biodegradation in constant electric field due to the enhanced removal of intermediate inhibitors produced from phenol. These intermediate may affect slightly microbial growth but the biodegradation capacity is enhanced. Method: The methodology adopted for this research comprises bioelectrochemical oxidative microbial biodegradation of phenol at constant anode potential. Results and Discussion: The obtained results revealed the positive effect of the electric field on the phenol biodegradation rate for all of the considered strains. There is certain anode potential at which the biodegradation rate is strongly affected for each strain. Research Implications: The research have both practical and theoretical implications. The practical importance consists in the enhanced biodegradation of severe pollutant as phenol is. The theoretical importance is within the specific impact of constant electric field on the enzyme activities in the studied strains. Originality/Value: This study contributes to the literature by the innovative approach and the practical aspects. The relevance and value of this research are demosntated by enhancement of phenol biodegradation in wastewater and water ponds.

Efficient removal of ammonia nitrogen via a coupled system of Ni1Cu0.2-Se-T/CP anode and copper foam cathode

Direct electrochemical oxidation is a green, clean and promising process for the treatment of ammonia nitrogen (NH4+-N) wastewater. Nevertheless, drawbacks of slow reaction kinetics and large overpotential greatly limit the ammonia oxidation reaction. To address the issue, Ni1Cu0.2-Se-T/CP was synthesized by the combination of heteroatom doping and in situ electrochemical oxidation (ISEO). Physical characterization shows that there are homogeneous and dense microscopic nanosphere particles on the electrode surface, which provide good attachment sites for the adsorption of reactants. Electrochemical tests further show that this catalytic electrode exhibits not only a high current density (37.17 mA·cm−2) at 0.65 V vs.Hg/HgO but also has the low Tafel slope (92.25 mV·dec−1) to ammonia oxidation reaction. Then, Ni1Cu0.2-Se-T/CP was applied as anode with copper as cathode to construct a coupled system. The area ratio of cathode/anode was optimized to improve the removal effect of ammonia nitrogen. The NH4+-N conversion efficiency of 100% was obtained at a constant anode potential of 0.65 V vs.Hg/HgO for 15 h when the cathode/anode area was 1:4. The system N2 selectivity up to 77.55%. This work provides a promising process for the green and efficient degradation of ammonia nitrogen wastewater.

Cooperative Fe sites on transition metal (oxy)hydroxides drive high oxygen evolution activity in base

Fe-containing transition-metal (oxy)hydroxides are highly active oxygen-evolution reaction (OER) electrocatalysts in alkaline media and ubiquitously form across many materials systems. The complexity and dynamics of the Fe sites within the (oxy)hydroxide have slowed understanding of how and where the Fe-based active sites form—information critical for designing catalysts and electrolytes with higher activity and stability. We show that where/how Fe species in the electrolyte incorporate into host Ni or Co (oxy)hydroxides depends on the electrochemical history and structural properties of the host material. Substantially less Fe is incorporated from Fe-spiked electrolyte into Ni (oxy)hydroxide at anodic potentials, past the nominally Ni2+/3+ redox wave, compared to during potential cycling. The Fe adsorbed under constant anodic potentials leads to impressively high per-Fe OER turn-over frequency (TOFFe) of ~40 s−1 at 350 mV overpotential which we attribute to under-coordinated “surface” Fe. By systematically controlling the concentration of surface Fe, we find TOFFe increases linearly with the Fe concentration. This suggests a changing OER mechanism with increased Fe concentration, consistent with a mechanism involving cooperative Fe sites in FeOx clusters.

Starvation combined with constant anode potential triggers intracellular electron storage in electro-active biofilms

The accumulation of electrons in the form of Extracellular Polymeric Substances (EPS) and poly-hydroxyalkanoates (PHA) has been studied in anaerobic processes by adjusting the access of microorganisms to the electron donor and final electron acceptor. In Bio-electrochemical systems (BESs), intermittent anode potential regimes have also recently been used to study electron storage in anodic electro-active biofilms (EABfs), but the effect of electron donor feeding mode on electron storage has not been explored. Therefore, in this study, the accumulation of electrons in the form of EPS and PHA was studied as a function of the operating conditions. EABfs were grown under both constant and intermittent anode potential regimes and fed with acetate (electron donor) continuously or in batch. Confocal Laser Scanning Microscopy (CLSM) and Fourier-Transform Infrared Spectroscopy (FTIR) were used to assess electron storage. The range of Coulombic efficiencies, from 25 to 82%, and the biomass yields, between 10 and 20%, indicate that storage could have been an alternative electron consuming process. From image processing, a 0.92 pixel ratio of poly-hydroxybutyrate (PHB) and amount of cells was found in the batch fed EABf grown under a constant anode potential. This storage was linked to the presence of living Geobacter and shows that energy gain and carbon source starvation were the triggers for intracellular electron storage. The highest EPS content (extracellular storage) was observed in the continuously fed EABf under an intermittent anode potential, showing that constant access to electron donor and intermittent access to the electron acceptor leads to the formation of EPS from the excess energy gained. Tailoring operating conditions can thus steer the microbial community and result in a trained EABf to perform a desired biological conversion, which can be beneficial for a more efficient and optimized BES.

Electrodeposition of Al foil for the collector of lithium-ion batteries by electrorefining in [Emim]Cl-AlCl3 ionic liquid with O2− ion at room temperature: Electrochemical dissolution behavior of Al anode

The continuous electrochemical dissolution of anode is significant to electrorefining in ionic liquid at room temperature. The electrochemically dissolved behavior of an aluminum anode was investigated in [Emim]Cl-AlCl3 ionic liquid with O2− ion by cyclic voltammetric method, constant potential dissolution, and SEM, EDS. It found that the dissolved process of the aluminum anode and electrodeposition of insulated darkness Al–O–Cl species exist together at a relatively low potential. Moreover, the Al–O–Cl species prevent the continuous dissolution of the aluminum anode. However, it can be electrochemically dissolved at a high potential that is beyond the anodic passivation potential, assuring continuous dissolution of the aluminum anode. Moreover, holding a constant anodic potential of 3.0 V for 30 min, we electrodeposited the dense and thin aluminum foil of 2.5 µm with a rough surface. The positive electrode of lithium-ion batteries using it as the collector shows superior properties.

Electrochemical behavior of zinc anode in acidic zinc electrolyte -influence of lead as an impurity in zinc anodic dissolution

Zinc is common metal used for steel protection. In this work, an alloy Zn-1 % wt. Pb was prepared by fusion at 500°C. The analysis of the corrosion behavior was studied with pure Zn anode as control in aerated solution of 0.9 M ZnSO4.7H2O + 1.63 M H2SO4 at 38°C.The effect of lead impurity on corrosion resistance of zinc anode in zinc electrorefining process was investigated using open circuit potential (OCP), Tafel plots, chronoamperometry at imposed constant anodic potential and electrochemical impedance spectroscopy (EIS) techniques. Samples were characterized by chemical analysis, optic microscope (OM) and X-ray diffraction (XRD). The results show that the lead impurity leads to degradation of the behavior of the alloy due to negative effect on the microstructure. Lead increases the corrosion rate and decreases the corrosion resistance of Zn-1 % wt. Pb alloy.

Bioelectrochemical methanation by utilization of steel mill off-gas in a two-chamber microbial electrolysis cell.

Carbon capture and utilization has been proposed as one strategy to combat global warming. Microbial electrolysis cells (MECs) combine the biological conversion of carbon dioxide (CO2) with the formation of valuable products such as methane. This study was motivated by the surprising gap in current knowledge about the utilization of real exhaust gas as a CO2 source for methane production in a fully biocatalyzed MEC. Therefore, two steel mill off-gases differing in composition were tested in a two-chamber MEC, consisting of an organic substrate-oxidizing bioanode and a methane-producing biocathode, by applying a constant anode potential. The methane production rate in the MEC decreased immediately when steel mill off-gas was tested, which likely inhibited anaerobic methanogens in the presence of oxygen. However, methanogenesis was still ongoing even though at lower methane production rates than with pure CO2. Subsequently, pure CO2 was studied for methanation, and the cathodic biofilm successfully recovered from inhibition reaching a methane production rate of 10.8 L m−2d−1. Metagenomic analysis revealed Geobacter as the dominant genus forming the anodic organic substrate-oxidizing biofilms, whereas Methanobacterium was most abundant at the cathodic methane-producing biofilms.

Effect of oxygen non-stoichiometry and redox phenomena in La/Ba–Sr–Co–Fe–O-based perovskite systems and its heterostructure as applicable in Solid Oxide Cell (SOC) air electrode

A-site dopant concentration driven oxygen non-stoichiometry in (Ba/La)1-xSrxCoyFe1-yO3-δ based mixed ionic and electronically conducting (MIEC) air electrodes having 0.2≤x≤0.6 and y = 0.8 was investigated through phase stability study vis-à-vis oxygen non-stoichiometry concentration (δ) determination and corelated with the vacancy mediated charge compensation mechanism in terms of oxygen reduction (ORR)/oxygen evolution (OER) reactions. The optimization for both BSCF and LSCF systems are found to be at La/Ba: Sr as 1.5:1. Optimized BSCF and LSCF-6482 based heterostructure (LS@BS) having hetero-interface was synthesized by adopting heterogeneous-heteromolecular nucleation and growth of LS on the seed of BS. While comparatively lower interfacial polarization of ∼0.0108 Ω cm2 is obtained for LS@BS heterostructure, the same for BSCF-6482 and LSCF-6482 are found to be 0.23 Ω cm2 and 0.02 Ω cm2 at 800 °C on GDC-based symmetrical cells. The time dependent losses in current under constant anodic (+0.8V) and cathodic potential (−0.8V) for 200h @800 °C for LS@BS and LSCF-6482are found to be ∼0.015 mA h−1 and ∼0.03 mA h−1 respectively and clinically corelated with the cell microstructure. Fuel-electrode supported cell with LS@BS air electrode exhibits a maximum current density of 2.4A.cm−2 @0.5V in FC and 0.48 A cm−2@1.5V, 60%RH (H2 flux 0.2Nlh−1.cm−2) having increasing trend with percentage RH in EC mode.

Enhancing arsenic (III) removal by integrated electrocatalytic oxidation and electrosorption reactions on nano-textured bimetal composite of iron oxyhydroxide and manganese dioxide polymorphs (α-, γ-, β-, and ε-MnxFe1−xO)

A composite electrode of manganese oxide (MnO2) incorporated with iron oxide (α-FeOOH) was synthesized for arsenite (As(III)) oxidation and subsequent arsenate (As(V)) electrosorption. The crystal structure and chemical state of MnO2 polymorphs were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and BET surface area. The redox couple of Mn(III)/Mn(IV) mediated the catalytic electron transfer with respect to As(III)/As(V) redox equilibrium. The Mn site contributed a high diffusive current to the redox capacitance, meanwhile the Fe site better provided the double-layer capacitive deionization for arsenic species. Electrolysis of arsenite under constant anodic potential mode (+1.0 V vs. Ag/AgCl) enabled assess the performance of the electrodes. Among the polymorphs, γ-Mn0.2Fe0.8O exhibited the best arsenic adsorption capacity of 48 mg-As g−1, compared to that of α-FeOOH NPs (15 mg-As g−1) and γ-MnO2 (7 mg-As g−1), based on multilayer Langmuir adsorption model.

Trade‐off between energy density and fast‐charge capability of lithium‐ion batteries: A model‐based design study of cells with thick electrodes

AbstractLithium‐ion batteries exhibit a well‐known trade‐off between energy and power, which is problematic for electric vehicles which require both high energy during discharge (high driving range) and high power during charge (fast‐charge capability). We use two commercial lithium‐ion cells (high‐energy [HE] and high‐power) to parameterize and validate physicochemical pseudo‐two‐dimensional models. In a systematic virtual design study, we vary electrode thicknesses, cell temperature, and the type of charging protocol. We are able to show that low anode potentials during charge, inducing lithium plating and cell aging, can be effectively avoided either by using high temperatures or by using a constant‐current/constant‐potential/constant‐voltage charge protocol which includes a constant anode potential phase. We introduce and quantify a specific charging power as the ratio of discharged energy (at slow discharge) and required charging time (at a fast charge). This value is shown to exhibit a distinct optimum with respect to electrode thickness. At 35°C, the optimum was achieved using an HE electrode design, yielding 23.8 Wh/(min L) volumetric charging power at 15.2 min charging time (10% to 80% state of charge) and 517 Wh/L discharge energy density. By analyzing the various overpotential contributions, we were able to show that electrolyte transport losses are dominantly responsible for the insufficient charge and discharge performance of cells with very thick electrodes.

Catalytic oxidation and deionization of nitrite and nitrate ions using mesoporous carbon-supported nano-flaky cobalt and nickel oxyhydroxides

The composite electrode of NiCo oxide supported by porous carbon was synthesized for nitrite oxidation and nitrate electro-sorption. The crystal structure and chemical state of the Co and Ni oxyhydroxides which were precipitated on loofah-derived activated carbon (AC) using hypochlorite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and BET surface area. The voltammetry showed that the redox couple of Co(II)/Co(III) and Ni(II)/Ni(III) as the mediator catalytically transferred the electrons of NO2–/NO3–; the Ni site had a relatively high transfer coefficient and diffusive current, while the Co site was better in the capacitive removal of the nitrite and nitrate compounds. A batch electrolysis of nitrite ions was operated under constant anodic potential mode (0 to + 1.5 V vs. Ag/AgCl) to assess the performance of the composite electrodes. The adsorption capacity of NiCo/AC (Ni = 5% and Co = 5% on AC by weight) was 23.5 mg-N g−1, which was twice that of AC substrate (7.5 mg-N g−1), based on a multilayer adsorption model. The steady-state kinetics of the consecutive reaction were derived to determine the rate steps of the electrochemical oxidation of NO2– and adsorption of NO3–.

Electrochemically deposited iridium-oxide: Estimation of intrinsic activity and stability in oxygen evolution in acid solution

Hydrated iridium oxyhydroxide (IrOx) films were electrochemically deposited from an alkaline oxalic solution at constant anodic potentials and by applying a potential cycling protocol, in both cases with variation of the electrodeposition time. From UV–vis spetroscopy of the solution for the deposition and their characterization it was concluded that a mixture of Ir(III)/Ir(IV) monomers participates in the deposition of IrOx film. X-ray photoelectron spectroscopy (XPS) of IrOx films indicated that both types of films contained hydrated Ir(IV) hydroxide as the dominant species, but in the film deposited by potential cycling the presence of the additional Ir(III) species was evident. The scanning electon microscopy (SEM) analysis of the surface morphology revealed that films deposited by potential cycling were more uniform than the films deposited at a constant potential. The amount of electrochemically active Ir-species on the surface of deposited IrOx films was estimated from the voltammetric charge of the Ir(III)/Ir(IV) transition. Depending on the film electrodeposition parameters, the values between 15 and 1080 nmol cm−2 were obtained. The electrochemically active surface area (ECSA) of IrOx films was calculated from cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements and ranged from 3 to 131 cm2 per 1 cm2 of geometric surface area for various films. The activity and stability of IrOx films toward oxygen evolution reaction (OER) was investigated in 0.5 M H2SO4 solution under potentiostatic conditions. The intrinsic activity, stated as turnover frequency and specific current density normalized per ECSA, showed that the OER activity of IrOx films deposited by potential cycling are up to two and a half times higher than the activity of films deposited at a constant anodic potential. Potentiostatic stability test showed a decrease in OER current over time for both type of the films. Determination of ECSA, the amount of electroactive Ir species, XPS spectrum and SEM imaging after the test indicated that the decrease in OER activity was caused by partial dissolution and delamination of the film as well as by oxidation of highly active hydroxide Ir(III) species.

Biofilm's morphology design for high sensitivity of bioelectrochemical sensor: An experimental and modeling study

High sensitivity is essential for the application of bioelectrochemical system-based sensor (BES sensor) in water quality early-warning, where the electroactive biofilm is of vital importance as it delivers a responsive electric signal to toxic substances. This study artificially designed the morphology of a naturally formed biofilm by employing a serrated knife to scrape the biofilm and thus obtained a reduced thickness and roughness. Then it was further cut by half to halve the biomass. BES sensors equipped with control and processed biofilms were operated under constant anode potential (CAP) and tested at different Cu(II) concentrations to study their sensitivities. Results revealed that the scraped biofilms delivered much increased sensitivity towards Cu(II) shock, which was attributed to a reduced thickness as illustrated by macroscopic and microscopic morphology analysis. Another finding was that biomass per unit interfacial area, rather than the biomass, also affected the sensitivity. To further describe how the inner biofilm responded the toxicity after morphology design, a one-dimension mass transfer model was developed to simulate the mass transfer of Cu(II) in the biofilms with different thicknesses. The relative threshold value of inlet Cu(II) concentration was employed to fit the modeling and experimental results, indicating that decreased biofilm thickness was beneficial for improving the sensitivity.

Microwave-assisted sol-gel synthesis of an Au-TiO2 photoanode for the advanced oxidation of paracetamol as model pharmaceutical pollutant

An Au-TiO2 photoanode on carbon cloth has been synthesized by microwave-assisted sol-gel method to treat paracetamol solutions at pH 3.0 by photocatalysis (PC), electro-oxidation (EO), photoelectrocatalysis with UVA light (PEC), solar PEC (SPEC) and hybrid methods with photoelectro-Fenton under UVA (PEC + PEF) and sunlight (SPEC + SPEF) irradiation at constant anodic potential (Ean). The photoanode has been characterized by XRD, Raman spectroscopy, HRTEM and SEM-EDS. The counter electrode was a 316L stainless steel plate, which was replaced by an air-diffusion electrode for H2O2 generation in hybrid treatments. The most powerful process was SPEC + SPEF, yielding total paracetamol removal in <30 min and 24% mineralization after 180 min, at Ean = +0.82 V. The paracetamol decay followed a pseudo-first-order kinetics in PEC. A lower rate constant was obtained upon increase of pharmaceutical concentration, showing good linear fit using a Langmuir-Hinshelwood model.

Electrochemical Corrosion Behavior of Monel Alloy in Carbonate Melts

The interaction of the monel alloy and its corrosion resistance in a melt of alkali metal carbonates in an oxidizing atmosphere was studied. The selectivity of alloy dissolution and modification of the electrode surface after storage at a constant anode potential were analyzed. The generation and development of local corrosion defects (pit corrosion, intercrystallite corrosion, corrosion cracking) on monel alloy (70% nickel, 28% copper), copper, and nickel electrodes in the molten eutectic of lithium, sodium, and potassium carbonates at a working temperature of 773 K were studied. The anode polarization was accompanied by a change in the state of the electrode surface.

Inhibition Effect of Natural Pozzolan and Zinc Phosphate Baths on Reinforcing Steel Corrosion

Zinc phosphate (ZnP) baths are widely used for increasing corrosion resistance and surface preparation for painting. Studies on exploiting these baths in the reinforced concrete (RC) are still in the early stages. This is probably due to the shortcomings, such as the alkaline instability and high porosity of the obtained coatings. Use of natural pozzolan (NP) as cement replacement is growing rapidly due to its economic, ecological, and technical benefits. The combined effect of using ZnP baths and NP-based cement on the resistance of concrete against damage caused by corrosion has been investigated. Four phosphating baths were prepared: ZnP, ZnP-Ni, ZnP-Cu, and ZnP-Mn. Steel specimens were phosphated at 55-60°C for 15 min. Concrete specimens were produced with four different levels of NP: 0% (control), 10 %, 20%, and 30%. The investigation was carried out using RC specimens where a constant anodic potential was impressed after 28 and 90 days of concrete curing. The electrochemical behavior of the coated steel has further been evaluated in chloride contaminated Ca(OH)2 saturated solution (CH-Cl) using the open circuit potential (OCP), the potentiodynamic polarization, and the polarization resistance with time. The bond strength between the coated steel and concrete has been evaluated by the pull-out test. Test results showed that concrete containing NP at higher replacement levels and steel specimens treated in bication baths exhibited corrosion initiation times several times longer than the control concrete with uncoated steel. In addition, the best corrosion performance was noted in the steel specimen treated in the ZnP-Cu bath. Its corrosion density was about twentyfold lower with respect to the bare steel, and its inhibition efficiency exceeded 95% in (CH-Cl) solution. In addition, its polarization resistance was about fifteenfold lower with respect to the bare steel. SEM, EDX, and XRD techniques have been employed, as well.

Development of a production chain from vegetable biowaste to platform chemicals

BackgroundA future bioeconomy relies on the development of technologies to convert waste into valuable compounds. We present here an attempt to design a biotechnological cascade for the conversion of vegetable waste into acetoin and electrical energy.ResultsA vegetable waste dark fermentation effluent containing mainly acetate, butyrate and propionate was oxidized in a bioelectrochemical system. The achieved average current at a constant anode potential of 0 mV against standard hydrogen electrode was 177.5 ± 52.5 µA/cm2. During this step, acetate and butyrate were removed from the effluent while propionate was the major remaining component of the total organic carbon content comprising on average 75.6%. The key players with regard to carbon oxidation and electrode reduction were revealed using amplicon sequencing and metatranscriptomic analysis. Using nanofiltration, it was possible to concentrate the propionate in the effluent. The effluent was revealed to be a suitable medium for biotechnological production strains. As a proof of principle, the propionate in the effluent of the bioelectrochemical system was converted into the platform chemical acetoin with a carbon recovery of 86%.ConclusionsTo the best of our knowledge this is the first report on a full biotechnological production chain leading from vegetable waste to the production of a single valuable platform chemical that integrates carbon elimination steps leading to the production of the valuable side product electrical energy.

Defective and “c-Disordered” Hortensia-like Layered MnOx as an Efficient Electrocatalyst for Water Oxidation at Neutral pH

The development of a highly active manganese-based water oxidation catalyst in the design of an ideal artificial photosynthetic device operating under neutral pH conditions remains a great challenge, due to the instability of pivotal Mn3+ intermediates. We report here defective and “c-disordered” layered manganese oxides (MnOx-300) formed on a fluorine-doped tin oxide electrode by constant anodic potential deposition and subsequent annealing, with a catalytic onset (0.25 mA/cm2) at an overpotential (η) of 280 mV and a benchmark catalytic current density of 1.0 mA/cm2 at an overpotential (η) of 330 mV under neutral pH (1 M potassium phosphate). Steady current density above 8.2 mA/cm2 was obtained during the electrolysis at 1.4 V versus the normal hydrogen electrode for 20 h. Insightful studies showed that the main contributing factors for the observed high activity of MnOx-300 are (i) a defective and randomly stacked layered structure, (ii) an increased degree of Jahn–Teller distorted Mn3+ in the MnO6 octa...

Anodic deposition of CoOOH films with excellent performance for electrochemical capacitors

Amorphous CoOOH films were fabricated on hexagonal graphite substrates in 0.2 M CoSO4 at a constant anodic deposition potential of 1.60 V vs Ag/AgCl (3 M KCl) under different deposition temperatures, and their electrochemical behaviors in 1 M NaOH and 1 M NaCl were systematically studied. The results showed that the deposition temperature had a significant effect on the electrochemical behaviors of the CoOOH films. For the four CoOOH films prepared under different deposition temperatures, when tested either in 1 M NaOH or 1 M NaCl, their area specific capacitance (C A) and cycle stability increased monotonously, their mass specific capacitance (C M) first increased and then decreased, while their bulk resistance (R bulk) and charge-transfer resistance (R ct) first decreased and then increased with increasing deposition temperature. In addition, the CoOOH films had high C M, good electrical conductivity, low faradic charge-transfer resistance, and low diffusive resistance. Among the four CoOOH films fabricated under different deposition temperatures, the film prepared under a deposition temperature of 45 °C (Sample 3) had the highest C M, the lowest R bulk, the lowest R ct, and good rate capability which can be ascribed to its structure with nanoparticles and nodules on its surface as well as its appropriate thickness. As a result, the CoOOH film fabricated by anodic deposition is a very promising electrochemical capacitor material for applications.