PbO2 Electrode Research Articles

Electrochemical Oxidation of Para-Aminophenol With Rare Earth Doped Lead Dioxide Electrodes: Kinetics Modeling and Mechanism.

In this study, La and Ce doped PbO2 electrodes were prepared and the characteristic of the electrodes were discussed with the help of structure analysis. The catalytic effects of the doped electrodes were explored through the degradation of para-aminophenol wastewater. The results showed that the para-aminophenol removal was 96.96%, 89.34%, and 77.55% after 180 min treatment with Ce-PbO2, La-PbO2, and PbO2, respectively. The para-aminophenol enhanced degradation mechanism was discussed with rare earth element doping electrodes and a kinetic model was established based on radical reactions mechanism with genetic algorithm (GA) calculation. The reaction constants of these electrodes were calculated and the results showed that the reaction constant of Ce-PbO2 electrode was the highest, which indicated that Ce-PbO2 electrode could have a better treatment effect. The EE/O was used as the index of energy consumption efficiency and the results were calculated and compared. This paper could provide basic data and technique reference of the prediction the oxidation reaction process of different electrodes for the electrochemical oxidation application in wastewater treatment.

Effect of Current Densities on the Microstructure and Electrochemical Behavior of the Porous β-PbO<sub>2</sub> Electrode

In order to obtain a titanium-based PbO2 electrode with high electrocatalytic activity and good stability, A porous β-PbO2 electrode is prepared by electrodepositing on titanium substrate Sn-Sb-RuOx coating. The surface morphology and phase analysis of the porous β-PbO2 electrode prepared at different current density were investigated by SEM and XRD. Results showed that the current density changes the surface morphology and active surface area of the porous β-PbO2 electrode. When the current density is 2 A/dm2, the surface of the porous β-PbO2 prepared by electrodeposition has a uniform porous morphology with a pore diameter of 50-200 µm with main crystal phase of β-PbO2. Influence of current density on the electrochemical activity of the electrode was analyzed using anodic polarization curve, electrochemical impedance spectroscopy and galvanostatic polarization. Results revealed that with the increase of current density, the oxygen evolution potential of the porous β-PbO2 electrode decreases first and then increases while the exchange current density first increases and then decreases. When the current density is 2 A/dm2, the oxygen evolution potential is 2.0075 V(at 0.05 A/cm2) and the maximum exchange current density is 1.77×10-4 A/cm2. According to the electrochemical impedance spectroscopy, when the current density is 2 A/dm2, Qf and Qdl are the largest, Rf and Rct are the smallest, and the RF first increases and then decreases with the current density increases. When the current density is 2 A/dm2, the maximum RF value is 655.7. The results with galvanostatic polarization at current density of 0.05 A/cm2 showed that the electrode has a minimum electrode voltage of 2.05 V at a current density of 2 A/dm2. Accelerated life experiments were carried out in 2 g/L Cl- and 150 g/L H2SO4 bath at 25 °C, and the porous β-PbO2 electrode obtained under the current density of 2 A/dm2 has the longest life, and the electrode life is 68 h, which is 2.5 times of the PbO2 electrode obtained under the current density of 4 A/dm2.

Electrochemical removal of amoxicillin using a Cu doped PbO2 electrode: Electrode characterization, operational parameters optimization and degradation mechanism

This work investigated the electrochemical degradation of amoxicillin (AMX) in aqueous solution with Cu-PbO2 electrode. The main influence factors on the degradation of AMX, such as Na2SO4 concentration, initial AMX concentration, current density and initial pH value, were analyzed in detail. Under the optimal conditions, the removal rates of AMX and chemical oxygen demand (COD) reached 99.4% and 46.3% after 150 min treatment. The results indicated that the electrochemical degradation of AMX fitted pseudo-first-order reaction kinetics. Compared with undoped PbO2 electrode, Cu-PbO2 electrode had a smaller crystal size, more proportion of hydroxyl oxygen species, greater AMX and chemical oxygen demand (COD) removal efficiency, higher average current efficiency (ACE) and lower electrical efficiency per log order (EE/O). Electrochemical oxidation using Cu-PbO2 electrodes was an effective way to eliminate amoxicillin in aqueous solution. Moreover, a possible degradation pathway including ring open and mineralization was proposed by intermediate products determined by GC-MS method. This paper could provide basic data and technique reference for the amoxicillin wastewater pollution control.

Polyethylene glycol assisted synthesis of a praseodymium-doped PbO2 electrode and its enhanced electrocatalytic oxidation performance

A praseodymium (Pr)-doped PbO2 electrode was synthesized by a co-deposition method with the help of polyethylene glycol (PEG). The morphologies and structures were characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical properties were investigated by linear sweep voltammetry, electrochemical impedance spectroscopy and accelerated life tests. 4-chlorophenol (4-CP) was used as a model pollutant to evaluate the electrocatalytic activity. The operating parameters for the degradation of 4-CP were optimized. The results indicated that the addition of PEG in the electrodeposition solution significantly promoted the deposition of Pr, resulting in a compact and robust film with vanished boundaries. The impedance of the electrode decreased greatly after the modification of Pr and PEG, which contributed to a good electrocatalytic performance. As compared with those of the undoped electrode, the average current efficiency and the energy consumption of the co-modified electrode increased by 96.8% and decreased by 60.0%, respectively. Additionally, the electrode stability experiments revealed that the lifetime of the co-modified electrode (320 h) was 3.3 times that of the undoped electrode. The improved performance could be attributed to both Pr doping and the addition of PEG in the deposition solution.

Physical and Electrochemical Performances of Cold Sprayed Pb Electrodes

Titanium-based PbO2 electrodes are widely used for chemical industries, such as electrodialysis, electrolysis, and electrodepositing, to improve the mechanical and life cycle properties of Pb metal electrodes. However, PbO2 electrodes are usually electrodeposited onto rigid metals due to its soft characteristic, which results in severe passivation problems requiring thin thickness and high porosity. It is of great importance to develop a rigid Pb metal electrode system since thermal spraying and welding methods fail to manufacture such a promising electrode. In the present work, the cold spraying method was used to deposit a pure Pb metal coating with thickness of above 500 μm on Q235 steel substrate. The coating has good physical performances, the porosity is less than 1%, and the bonding strength ranges from 6.25 to 7.75 MPa. The cross-sectional morphology suggests that no through-thickness pores exist in the coating. The oxygen evolution potential is larger than 1.5 V vs. SCE, which is similar to the potential of the titanium-based PbO2 electrode. Dynamic polarization curves and cyclic voltammetry curves of coated sample in sodium sulfate solution indicate that cold sprayed Pb coating is a good electrode for electrochemical reduction reactions. All our results mean that cold spraying is capable of manufacturing electrode materials for electrochemical industries.

Fabrication and nucleation study of β-PbO2–Co3O4 OER energy-saving electrode

In this study, β-PbO2–Co3O4 composite coatings were synthesized on a substrate using the electrodeposition method in an electrolyte containing Pb2+ and Co3O4 particles. The preparation process study shows that the β-PbO2 bath containing Co3O4 particles becomes more stable for an ultrasonic dispersion time within 30 min, with the stability beginning to decrease after the ultrasonic time exceeds 30 min. Co3O4 particles in the β-PbO2 bath are positively charged, with anions being adsorbed onto the particles. The nucleation behavior study shows that the electric field force plays a dominant role in the adsorption process for the Co3O4 particles. The nucleation and growth of β-PbO2 on the Co3O4 particles started for the particles closer to the substrate. In addition, the thickness of the β-PbO2 layer on the Co3O4 particles was inversely proportional to the distance between the Co3O4 particles and the substrate. Compared to the pure PbO2 electrode, the oxygen evolution overpotentials for the β-PbO2–Co3O4 electrode are decreased significantly, which demonstrates an energy-saving effect.

Physicochemical characterization of PEG-modified PbO2 coatings electrodeposited from a methanesulfonate bath

This study explores the preparation and application of polyethylene glycol (PEG)-modified PbO2 electrodes. The PEG-modified PbO2 coatings were electrodeposited on a Ti/SnO2-Sb substrate from a methanesulfonate electrolytic bath containing different amounts of PEG. Structural and morphologic characterization was carried out for the deposited electrodes. The presence of PEG in the deposition bath represses the nucleation process and grain growth process in PbO2 deposition. Increasing PEG addition results in an increased [Formula: see text]-PbO2 content and decreased crystallite size. At a limited PEG addition [Formula: see text]4 g/L, a rough and pyramidal surface morphology is presented in the PbO2 coatings. A higher PEG addition at 6 g/L leads to a dense and smooth coating surface yet with less uniformity. Electrochemical characterization reveals a great electrocatalytic activity for the modified PbO2 electrodes when the PEG addition is [Formula: see text]4 g/L.

A novel layer-by-layer CNT/PbO2 anode for high-efficiency removal of PCP-Na through combining adsorption/electrosorption and electrocatalysis

Electrochemical oxidation is an effective mean to degrade non-biodegradable organics from the contaminated waters. However, its current efficiency is very low for the low-concentration organic pollutants treatment. In this work, combining with the outstanding adsorption property of CNT and the effective electrocatalytic oxidation performance of β-PbO2, we constructed novel layer-by-layer carbon nanotube/PbO2 anodes (CNT/PbO2-3, CNT/PbO2-4 and CNT/PbO2-5) with high adsorbability to enhance the electrochemical degradation efficiency of low-concentration sodium pentachlorophenate (PCPNa). In electrochemical oxidation tests, the PCP-Na was rapidly enriched in the CNT/PbO2 film through adsorption/electrosorption and then efficiently degraded in site. The removal efficiency of low-concentration PCP-Na (5 mg/L) on CNT/PbO2-4 reached 73.8% after only 5 min of electrolysis, whereas that on pure PbO2 was only 9.9%. To further clarify the mechanism of improvement of PCP-Na removal on CNT/PbO2-4 anode, the generation capacity of·OH radicals, oxygen evolution overpotential, voltammetric charge quantity, interface resistance, and specific surface area of CNT/PbO2-4 anode were also assessed and compared with those of other three anodes. Results showed that, in addition to the synergistic effect of adsorption/electrosorption and electrocatalysis, the more active sites, smaller electron transfer resistance and higher direct oxidation capacity of CNT/PbO2-4 anode also contributed to improving degradation rate of PCP-Na on CNT/PbO2-4 anode. Additionally the electrochemical degradation pathway of PCP-Na was also proposed based on the gas chromatography-mass spectrometry analysis. Finally, CNT/PbO2-4 electrode exhibited longer accelerated lifetime of 116 h than pure PbO2 electrode (91 h). Thus, these findings provide a new anode to improve the removal of low-concentration organic pollutants through combining electrochemical oxidation and adsorption/electrosorption processes.

Recent developments and advances in Ti/TiO2-NTs/PbO2 electrodes:A general Review of their controllable preparation and application in wastwater treatment

Ti/TiO2-NTs(nanotubes)/PbO2 is a new composite electrode material,which has been considered as an optimal electrode material for electrochemical oxidation of organic contaminants in the aquatic environmentthat due to its its good physical and chemical properties,such as good electrocatalytic activity, high oxygen evolution potential, corrosion resistance, good stability, environmental friendliness and simple preparation. The fundamental research and practical application of Ti/ TiO2-NTs(nanotubes)/PbO2 electrodes in the mineralization of organic pollutants have been well developed up to now. So this paper mainly reviews the preparation methods of Ti/TiO2-NTs/ PbO2 electrodes and the structural characterization methods of electrode materials first. And then, the basic principle of electrocatalytic oxidation will be introduced in detail and the application of this electrodes in water treatment is going to be summarized systematically. Further, we also proposed the existing problems in recent research and the potential development direction of electrocatalytic water treatment technology in the future, which could provide reference for the follow-up research.

Preparation and Electrocatalytic Performance of Nanosphere Array PbO2 Electrode on Stainless Steel-Based Grid-Like ZnO Film

A nanosphere array PbO2 electrode was constructed on as-prepared stainless steel-based grid-like ZnO film via anodic oxidation in lead nitrate solution. The above grid-like ZnO film was prepared in zinc nitrate solution by electrodeposition using polystyrene (PS) microsphere templates. The morphology and composition were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The performance was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) measurements. The results showed that the active layer of the array PbO2 electrode possesses a regular petal-like array structure that consists of many clustered PbO2 nanospheres. The array structure can increase the electrochemical active surface area (ECSA). The total voltammetric charge (qT*) is 2.6 times that of the traditional PbO2 electrode. Additionally, the array electrode shows a larger exchange current density (i0), lower activation energy (Ea) and charge transfer resistance (Rct) during the process of oxygen evolution. In the degradation process of phenol, the degradation rate constant of the array PbO2 electrode is significantly greater than that of a traditional PbO2 electrode. The results demonstrated that the array PbO2 electrode with enhanced electrocatalytic performance is a promising material for degrading organic effluents.

Electrochemical oxidation of sulfamethoxazole using Ti/SnO2-Sb/Co-PbO2 electrode through ANN-PSO

Even in a trace amounts, the presence of antibiotics in aqueous solution is getting more and more attention. Accordingly, appropriate technologies are needed to efficiently remove these compounds from aqueous environments. In this study, we have examined the electrochemical oxidation (EO) of sulfamethoxazole (SMX) on a Co modified PbO2 electrode. The process of EO of SMX in aqueous solution followed the pseudo-first-order kinetics, and the removal efficiency of SMX reached the maximum value of 95.1 % within 60 min. The effects of major factors on SMX oxidation kinetics were studied in detail by single-factor experiments, namely current density (1?20 mA cm-2), solution pH value (2?10), initial concentration of SMX (10?500 mg L-1) and concentration of electrolytes (0.05?0.4 mol L-1). An artificial neural network (ANN) model was used to simulate this EO process. Based on the obtained model, particle swarm optimization (PSO) was used to optimize the operating parameters. The maximum removal efficiency of SMX was obtained at the optimized conditions (e.g., current density of 12.37 mA cm-2, initial pH value of 4.78, initial SMX concentration of 74.45 mg L-1, electrolyte concentration of 0.24 mol L-1 and electrolysis time of 51.49 min). The validation results indicated that this method can ideally be used to optimize the related parameters and predict the anticipated results with acceptable accuracy.

Template-free electro-synthesis of PbO2 nanorod with chrysanthemum-like array

PbO2 electrode is one of crucial materials in electrochemical field, however, the fabrications of nanostructured PbO2 materials are highly confined to the template method. In this work, the nanostructured PbO2 materials were controllably synthesized by template-free electrodeposition method. It is found that the microstructure of PbO2 material was highly depended on the electrochemical deposition models, i.e., cyclic voltammetry (CV) method, potentiostatic method (PM), pulse potentiostatic method (PPM) and pulse galvanostatic method (PGM). Especially, PbO2 nanorod built by nanoparticles with chrysanthemum-like array synthesized in the absence of template by pulse potential deposition method showed high specific capacitance and good stability for supercapacitor application.

Electrochemical degradation of insecticide hexazinone with Bi-doped PbO2 electrode: Influencing factors, intermediates and degradation mechanism

Electrochemical degradation of hexazinone in aqueous solution using Bi-doped PbO2 electrodes as anodes was investigated. The main influencing parameters on the electrocatalytic degradation of hexazinone were analyzed as function of initial hexazinone concentration, current density, initial pH value and Na2SO4 concentration. The experiment results showed that the electrochemical oxidization reaction of hexazinone fitted pseudo-first-order kinetics model. 99.9% of hexazinone can be decontaminated using Bi-doped PbO2 electrode as anode for 120 min. Comparing with pure PbO2 electrode, the Bi-doped PbO2 electrodes possess higher hexazinone and COD removal ratio, higher ICE and lower energy consumption in the electrocatalytic degradation process. The results revealed that electrochemical oxidation using Bi-doped PbO2 anodes was an efficient method for the elimination of hexazinone in aqueous solution. The electrocatalytic oxidization mechanism of hexazinone with Bi-doped PbO2 anode was discussed, then the possible degradation pathway of hexazinone with two parallel sub-routes was elucidated according to 15 intermediates identified using HPLC-MS.

Electrochemical oxidation of acetamiprid using Yb-doped PbO2 electrodes: Electrode characterization, influencing factors and degradation pathways

The Yb-doped PbO2 electrodes were fabricated by electrodeposition method. SEM and XRD experiments revealed that the adulteration of Yb can decrease the crystal grain size and make the electrodes more compact. Electrochemical measurements, accelerated service lifetime and bulk electrolysis experiments proved that Yb-doped PbO2 electrodes had higher oxygen evolution overpotential, stability and acetamiprid removal ratio than pure PbO2 electrodes. The effect of operating parameters, such as current density, initial acetamiprid concentration, and pH value, on the electrocatalytic degradation of acetamiprid were systematically studied. The electrocatalytic oxidation reaction of acetamiprid on Yb-doped PbO2 electrodes was highly effective, which obeyed the pseudo-first-order kinetics model. Intermediates analysis and electrocatalytic degradation mechanism of acetamiprid by Yb-doped PbO2 electrodes were implemented, and the degradation pathways were divided into three different sub-routes due to three function groups on acetamiprid initially attacked by hydroxyl radicals. Finally, all the byproducts were decontaminated into CO2 and H2O. These results proved that Yb-doped PbO2 electrodes have more promising application potential for the electrocatalytic degradation of refractory organic pollutants.

Study on Electrochemical Oxidation of m-Nitrophenol on Various Electrodes Using Cyclic Voltammetry

The electrochemical oxidation behavior of m-nitrophenol (m-NP) was studied comparatively on glassy carbon electrode, Pt electrode, PbO2 electrode, SnO2 electrode, and graphite electrode using cyclic voltammetry. The cyclic voltammetry measurements were performed in acidic (1 M H2SO4, pH 0.4), neutral (1 M Na2SO4, pH 6.8), and alkaline (1 M NaOH, pH 12.0) media to investigate the effect of pH value on the oxidation of m-NP. The fouling of electrodes was also studied during cyclic voltammetry measurements. The results indicate that both of the electrode material and the pH value of supporting electrolyte had a significant influence on the oxidation of m-NP. In acidic medium, m-NP was irreversibly oxidized on glassy carbon electrode, Pt electrode, SnO2 electrode, and graphite electrode at 1.23, 1.26, 1.26 and 1.27 V, respectively, while there was no any oxidation peak for PbO2 electrode. In a neutral medium, m-NP yielded well-defined oxidation peaks on all electrodes, although the height and potential of the peaks depended on the material of electrodes. In the alkaline medium, the m-NP could be directly oxidized only on glassy carbon electrode and graphite electrode, but their peaks were not well defined because the oxidation of m-NP occurs closer to oxygen evolution potential region. In addition, the oxidation peaks appeared at the lower potential value in the alkaline medium than in neutral and acidic media. Under all conditions, except in the alkaline solution and on glassy carbon electrode, the passivation of electrodes occurred during continual scans.

Fabrication of Ga2O3–PbO2 electrode and its performance in electrochemical advanced oxidation processes

Owing to its high oxygen evolution potential, PbO2 electrode is one of the candidates for electrochemical advanced oxidation processes (EAOPs). To further improve its performance as EAOP electrode, a Ga2O3-doped PbO2 electrode (Ga2O3–PbO2 electrode) was fabricated by the composite plating method. SEM and XRD results showed that the crystalline in the coating of Ga2O3–PbO2 electrode is more uniform and in smaller size than that in the undoped PbO2 electrode, which provided a higher specific surface area. The electrochemical studies showed that the Ga2O3–PbO2 electrode had higher oxygen evolution potential (OEP) and smaller electrode surface impedance, which is a benefit for the formation of hydroxyl radicals (·OH). The electrochemically degradation test using bromocresol green sodium (BG) solution and glucose solution as the simulated wastewater showed that the kinetics of electrochemical catalytic degradation is a pseudo-first-order reaction, and the reaction rate constant on Ga2O3–PbO2 electrode was 2 times accelerated.

Electrochemical oxidation of pyrrole, pyrazole and tetrazole using a TiO2 nanotubes based SnO2-Sb/3D highly ordered macro-porous PbO2 electrode

A highly ordered three-dimensional macro-porous PbO2 (3D porous PbO2) electrode has been prepared for electrochemical oxidation of nitrogen-heterocyclic compounds. The 3D porous PbO2 electrode was fabricated by templated electrochemical deposition method with TiO2 nanotube arrays as substrate and SnO2-Sb as intermediate layer. The morphology and composition characterization of the 3D porous PbO2 electrode was performed by field emission scanning electron microscopy and X-ray diffraction, which revealed a uniform distribution of highly ordered macro-porous β-PbO2 structure. The Brunner−Emmet−Teller analysis suggested the electrode possessed large specific surface area of 37.39 m2·g−1. Electrochemical measurements indicated the electrode had a favourable oxygen evolution potential of 1.89 V and inner voltammetric charge of 14.48 mC·cm−2, which were higher than that of conventional PbO2 electrode. Furthermore, the electrochemical oxidation and TOC removal percentage of pyrrole, pyrazole and tetrazole obtained by 3D porous PbO2 electrode were 93.4%, 72.7%, 61.2% and 66.7%, 57.3%, 38.6% respectively, which were also superior to conventional PbO2 electrode. The intermediates were detected and analyzed by high-performance liquid chromatography, gas chromatography-mass spectrometer, and ion chromatography to propose a degradation pathway of pyrrole, pyrazole and tetrazole. Finally, quantum chemical calculation was introduced in this study by density function theory method, which is consistent with the experimental detection.

Structure dependent electrochemical performance of PbO2 thin-film electrode

Various structured PbO2 electrodes were prepared by surfactant-assisted anodic electrodeposition method. PbO2-PEG thin-film electrode is composed of small particles and shows a smooth surface. PbO2-PVA electrode displays a unique structure in which the PbO2 particles are embed in the PVA network structure. PbO2-AOT electrode consists of bull-horn like particles. The morphologies and structures of PbO2 electrodes are highly influenced by the surfactant. PEG and PVA can decrease the particle size of PbO2 particle and AOT can dramatically alter the morphology of PbO2 particle. PbO2-PEG, PbO2-PVA, and PbO2-AOT electrodes exhibit excellent electrocatalytic activity, stability, corrosion resistance, and long service life compared with bare PbO2 electrode. This work demonstrates the relationship between the structure and electrochemical performances of PbO2 electrodes, and provides a feasible approach to fabricate stable structured electrode.

Optimized Fabrication of TiO2 Nanotubes Array/SnO2-Sb/Fe-Doped PbO2 Electrode and Application in Electrochemical Treatment of Dye Wastewater

A TiO2 nanotubes array/SnO2-Sb/Fe-doped PbO2 electrode with high oxygen evolution potential and enhanced electrochemical oxidation performance was successfully manufactured. The surface morphology and electrochemical performance of the electrode were characterized by a field emission scanning electron microscope, linear sweep voltammetry, and electrochemical impedance spectroscopy experiments. The effect of Fe doping concentration on the electrode performance was also investigated. This study shows the doping of Fe on a PbO2 electrode improved the micro-morphology and the conductivity of the electrode. The oxygen evolution potential was also increased to 1.95 V [versus a saturated calomel electrode (SCE)] via Fe doping. The optimal condition of Fe doping concentration was 0.02 M. The optimized electrode showed that the decoloration rate and total organic carbon removal ratio of methylene blue approached 98% and 96% after 30 min of electrochemical treatment, respectively. The accelerated lifetime of the optimized Fe-doped electrode was approximately 4.3 times larger than that of the undoped PbO2 electrode. A Ti/TiO2 nanotubes array/SnO2-Sb/Fe-doped PbO2 anode shows potential application in the electrochemical treatment of organic dye wastewater.

Preparation and Supercapacitive Performance of Lead Dioxide Electrodes with Three-Dimensional Porous Structure

The three-dimensional porous structure PbO2 electrodes (3D-PbO2 electrodes) were prepared in the lead nitrate solution by potentiostatically electrodeposition method using oxygen bubble as dynamic template, which can be used as the positive materials of the supercapacitors. The morphology and structure of 3D-PbO2 electrodes were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The supercapacitive performance of 3D-PbO2 electrodes were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge tests (GCD) and electrochemical impedance spectroscopy (EIS). The specific capacitance of 3D-PbO2 electrodes can reach 195.6 F g–1 at 0.2 A g–1, which is 2.8 times higher than that of Flat-PbO2 electrodes (68.8 F g–1). The charge transfer resistance (Rct) of 3D-PbO2 electrodes (8.21 Ohm cm–2) is lower than that of Flat-PbO2 electrodes (21.32 Ohm cm–2). The excellent supercapacitive performance of 3D-PbO2 electrodes can be attributed to the three-dimensional porous structure, which can enlarge the active surface area of lead dioxide electrodes and promote the electrolyte diffusion and electrons propagation.