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In present work, SnO2 nanoparticles were synthesized using simple hydrothermal process, and then a novel PbO2/SnO2 electrode was successfully fabricated using obtained SnO2 nanoparticles for electrochemical oxidation of 3-chlorophenol (3-CP). The microstructure, element distribution, crystal structure and chemical composition of samples were characterized by the analytical techniques including SEM, EDS, XRD and XPS. The electrochemical performances of electrodes were evaluated using LSV and CV measurements. The ·OH radicals generation capacity of electrodes was determined using terephthalic acid as trapping agent. Moreover, the PbO2/SnO2 electrodes were applied in the electrochemical degradation of 3-CP in aqueous solution. The results show that the doping of SnO2 nanoparticles reduced the grain size of PbO2 crystal and improved the content of Oads on the surface of electrode. In contrast with the pure PbO2 electrode, the PbO2/SnO2-1.0 electrode (the concentration of SnO2 in electroplating solution was 1.0 g/L) exhibited higher oxygen evolution potential, stronger direct oxidation capacity and ·OH radicals generation capacity, and superior electrochemical activity for degradation of 3-CP. The intermediates formed in electrochemical degradation of 3-CP were revealed by HPLC and a plausible degradation pathway was proposed. Furthermore, PbO2/SnO2-1.0 electrode also showed a high reusability for 3-CP degradation.

To improve the electrocatalytic performance of PbO2 anode, the titanium mesh was used as substrate to fabricate a three-dimensional networked PbO2 (3DN-PbO2) anode. The morphology, structure, composition, and electrochemical performance of 3DN-PbO2 anode were evaluated using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ·OH radicals generation test, cyclic voltammetry, electrochemical impedance spectroscopy, as well as electrochemical oxidation of p-nitrophenol (p-NP). Compared with traditional two-dimensional planar PbO2 (2DP-PbO2) anode, the 3DN-PbO2 anode possessed smaller crystal size, more compact structure, more chemisorption oxygen, stronger ·OH radicals generation ability, more abundant active sites, and smaller electron transfer resistance, resulting in better electrocatalytic performance for degradation of p-NP. The degradation rate constant (kapp) of p-NP on 3DN-PbO2 anode was 0.0489 min–1, more than 2 times that of 2DP-PbO2 anode (0.0229 min–1). In addition, the influence of operating parameters (current density, pH and temperature) on the p-NP degradation and the degradation pathway of p-NP were also investigated. Finally, the stability of electrodes was estimated using 15-cycle electrochemical oxidation test and accelerated lifetime test, and both of 3DN-PbO2 and 2DP-PbO2 electrodes exhibited high reusability for p-NP degradation.

A novel nano powdered PbO2 (NP-PbO2) electrode was fabricated in our previous study as a highly efficient anode material for electrocatalytic oxidation, but it is still challenged by its high charge transfer resistance. Herein, three-dimensional graphene (3DG) was composited with NP-PbO2 to solve this problem. Due to the multidimensional electrical transmission channels provided by 3DG, the charge transfer resistance of NP-PbO2 was greatly reduced from 3.08 × 105 to 7.74 × 103 Ω/cm2, thereby significantly boosting the hydroxyl radical generation capacity of NP-PbO2 electrode. In electrocatalytic oxidation process of 2,4-dichlorophenol (2,4-DCP), the optimal 3DG-PbO2 composite anode exhibited excellent eletrocatalytic activity. After 60 min of electrolysis, the mineralization current efficiency at 3DG-PbO2 electrode was 1.68 and 3.38 times higher than those at NP-PbO2 and electrodeposited PbO2 (ED-PbO2) electrodes, respectively. The influence of several important operation parameters on the 2,4-DCP removal efficiency was examined. The results show that the 2,4-DCP removal reached 97.67% after 80 min of electrolysis under the conditions of current density 4 mA/cm2, initial 2,4-DCP concentration 50 mg/L, pH 3 and Na2SO4 concentration 0.05 M. In addition, the degradation mechanism of 2,4-DCP was explored via theoretical computation (frontier molecular orbitals, molecular electrostatic potential, total charges, Fukui functions and transient states) and experimental identification of intermediates. Accordingly, we proposed the mineralization pathway of 2,4-DCP at the 3DG-PbO2 anode.

In present work, a hydrophobic PbO2 electrode modified by sodium dodecyl benzene sulfonate (SDBS-PbO2) was fabricated using electrodeposition method. The effect of SDBS concentration in electroplating bath on the surface morphology, structure, electrochemical properties, hydrophilicity, OH generation ability and stability of SDBS-PbO2 electrodes was studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), water contact angle, fluorescence probe technique, and accelerated life test, respectively. Results showed that SDBS modification not only increased the electro-catalytic activity, but also prolonged the service life of PbO2 electrode. The electrode prepared from the electroplating bath containing 10 mg/L SDBS (SDBS-PbO2-10 mg/L) showed the highest electrocatalytic activity and the longest service life. The electrochemical degradation of nitrobenzene (NB) in simulated wastewater was used to evaluate the potential application of SDBS-PbO2 electrodes for wastewater treatment. The highest NB removal efficiency and total organic carbon (TOC) removal efficiency of 89.35% and 52.62% were both obtained by SDBS-PbO2-10 mg/L anode. Thus, the SDBS-PbO2-10 mg/L anode was used to systematically investigate the effects of applied current density, initial NB concentration, temperature, and pH value on the reaction kinetics and mineralization current efficiency (MCE) of NB degradation. It was found that the increase of applied current density and the reduction of initial NB concentration exerted a prominent effect on the degradation of NB, but caused the decrease of MCE, while high temperature and low pH value improved both NB degradation rate and MCE. These results show that the SDBS-PbO2-10 mg/L electrode may become a promising anode for organic pollutant degradation.

Sheet-like Co(OH) 2 /Al(OH) 3 or Co(OH) 2 nanomaterial has been synthesized on conducting carbon fiber paper (CFP) by a facile one-step electrochemical deposition. The binder-free Co(OH) 2 /Al(OH) 3 /CFP displays an improved electrical conductivity, electrochemical activity and material utilization than solitary Co(OH) 2 , therefore Co(OH) 2 /Al(OH) 3 nanomaterial exhibits improved electrochemical properties (a maximum capacitance of 1006 Fg −1 at 2 Ag −1 , with 77% retention even at a high current density of 32 Ag −1 , and more than 87% of the capacitance retention after 10000 cycles at 32 Ag −1 ) in comparison to that of the Co(OH) 2 /CFP (709 Fg −1 , 65%, 79%). In addition, an asymmetric supercapacitor (ASC) fabricated with Co(OH) 2 /Al(OH) 3 /CFP positive electrode and AC/CFP negative electrode demonstrates ultrahigh specific capacitance (75.8 Fg −1 ) and potential window (1.7 V). These encouraging results make these low-cost and eco-friendly materials promising for high-performance energy storage application.

To improve the electrochemical activity and stability of PbO2 electrode, In2O3 particles were doped into β-PbO2 active layer by composite electrodeposition technology. When the In2O3 concentration in electrodeposition solution was 2 mM, the In2O3-PbO2 electrode had larger specific surface area, tighter crystal structure, higher oxygen evolution potential (2.09 V vs. SCE), smaller charge transfer resistance (64.32 Ω/cm2), stronger ability to generate hydroxyl radicals (0.213 μM/min) and thereby the better electrocatalytic activity and stability. In electrochemical oxidation of norfloxacin (NOR), the NOR removal rate at the In2O3-PbO2 anode was 1.388 times faster than that at pristine PbO2 electrode. Additionally, the effects of current density, initial pH, initial NOR concentration and electrolyte concentration on NOR removal efficiency were investigated by the principle of single variable. With the increase of current density and the decrease of initial NOR concentration, the NOR removal efficiency increased significantly; the better degradation effect was obtained under pH 3 and Na2SO4 concentration of 0.2 M. Finally, the degradation mechanism of NOR was discussed and five possible degradation pathways were proposed.

In this study, the Indium doped Ti/PbO2 electrode (marked as Ti/In-PbO2) was prepared via simple electrodeposition technology for electrochemical degradation of cefalexin (CLX). To obtain the effect of Indium on the electrochemical activity and stability of Ti/PbO2 electrode and optimize the doping amount of Indium, the morphology, crystal structure, element state, electrochemical activity and stability of Ti/In-PbO2 electrodes with different Indium amounts were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS) and Tafel curve. The results showed that when the InNO3 concentration in electrodeposition solution was 15 mM/L, the Ti/In-PbO2 electrode possessed the best electrocatalytic activity and the highest stability due to its denser structure, finer grains, larger specific surface area, and stronger ability to generate hydroxyl radicals. The electrochemical degradation rate constant of CLX at Ti/In-PbO2 anode was 1.93 times faster than that at pristine Ti/PbO2 electrode. Additionally, the influence of current density, initial pH, initial CLX concentration and electrolyte concentration on removal efficiency of CLX was investigated and the degradation pathway of CLX was proposed.

A novel PbO2 electrode with a graphene nanosheet interlayer (marked as GNS-PbO2) was prepared combining electrophoretic deposition and electro-deposition technologies. The micro morphology, crystal structure and surface chemical states of GNS-PbO2 electrodes were characterized using scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Their electrochemical properties and stability were determined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ·OH radicals test and accelerated life test, and compared with traditional PbO2 electrodes. Besides, their potential application in the electrochemical degradation of 2-chlorophenol (2-CP) was investigated. The GNS-PbO2 electrode possessed perfect octahedral β-PbO2 microcrystals, and its grain size was much smaller than that of traditional PbO2 electrode. It exhibited higher electrochemical activity than traditional PbO2 electrode due to its larger electrochemical active surface area and stronger ·OH radicals generation ability. The service lifetime of GNS-PbO2 electrode (107.9 h) was 1.93 times longer than that of traditional PbO2 electrode (55.9 h). The electrochemical degradation rate constant of 2-CP on GNS-PbO2 electrode (kapp = 2.75 × 10−2 min−1) is much higher than for PbO2 electrode (kapp = 1.76 × 10−2 min−1). 2-CP oxidation yielded intermediates including aromatic compounds (catechol, phenol and ortho-benzoquinone) and organic acids (oxalic acid, maleic acid and glutaconic acid), and a possible degradation pathway for 2-CP was proposed accordingly.

In this work, a three-dimension grapnene-PbO2 (3DG-PbO2) composite anode was prepared using coelectrodeposition technology for electrocatalytic oxidation of perfluorooctane sulfonate (PFOS). The effect of 3DG on the surface morphology, structure and electrocatalytic activity of PbO2 electrode was investigated. The results indicated that the 3DG-PbO2-0.08 anode (3DG concentration in electrodeposition solution was 0.08 g L−1) possessed the best electrocatalytic activity due to its stronger ·OH radicals generation capacity, more active sites and smaller charge-transfer resistance. The degradation rate constant of PFOS on 3DG-PbO2-0.08 anode was 2.33 times than that of pure PbO2 anode. Additionally, the by-products formed in electrocatalytic degradation of PFOS were identified and a PFOS degradation pathway was proposed accordingly, which was dominated by the dissociation of –CF2- groups via the attack of ·OH radicals. Finally, the toxicity evolution of degradation solution was examined to evaluate the ecological risk of electrocatalytic oxidation of PFOS by acute toxicity assays to zebrafish embryos.

PbO 2 and SnO 2 are two promising anode materials for electrochemical oxidation. In order to highlight the difference between two kinds of electrodes in an electrochemical oxidation process, their morphology, structural, oxygen evolution overpotential (OEP), electrochemical activity and service life-time were compared in detail in this paper. Surface characterization by scanning electron microscope shows that the film of the PbO 2 electrode is even, compact, non-porous, and non-cracked, while many cracks are present on the film of the SnO 2 electrode. Electrochemical studies based on linear sweep voltammetry (LSV) and cyclic voltammetry (CV) prove that the OEP for the SnO 2 electrode was much higher than that of the PbO 2 electrode, and the electron-transfer kinetics and the reversibility of electrode reaction of the SnO 2 electrode were superior to those of the PbO 2 electrode. In electrochemical decomposition of p -nitrophenol, the degradation ratios at PbO 2 and SnO 2 anodes achieved 86.9% and 96.5%, respectively, after 120 min electrolysis, which verified the results of LSV and CV. The accelerated lifetime tests show that the service life time of the SnO 2 electrode is far shorter than that of the PbO 2 electrode, even though it was shown to be superior to the PbO 2 in electrocatalytic activity.

A novel PbO2 electrode (marked as CNT–PbO2) with a carbon nanotube (CNT) interlayer was prepared by electrophoretic deposition and electro-deposition. The surface morphology, structure, electrochemical activity and stability of the CNT–PbO2 electrodes were characterized by scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ·OH production test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), bulk electrolysis and accelerated life test. The results show that, compared with the traditional PbO2 electrode, the CNT–PbO2 electrodes electrodeposited β-PbO2 outer layer above the CNT interlayer had a higher crystallinity. The CNT–PbO2-5 min electrode had a higher active surface area and lower charge transfer resistance than traditional PbO2, CNT–PbO2-10 min, and CNT–PbO2-15 min electrodes due to a large number of exposed CNTs. However, the CNT–PbO2-10 min electrode exhibited a stronger ability of ·OH production, higher direct oxidation capacity for degradation of 4-chlorophenol (4-CP) and longer service lifetime than other electrodes, whose apparent rate constant for 4-CP degradation and service lifetime was 2.7 times and 1.7 times those of traditional PbO2 electrode, respectively. Thus, the proposed CNT–PbO2-10 min electrode in this study is a promising anode for the electrochemical oxidation of refractory toxic organic pollutants.

In this study, three kinds of SnO2 particles were synthesized by hydrothermal treatment with the assistance of three different surfactants of cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS). The synthesized SnO2-CTAB, SnO2-SDBS and SnO2-SDS microparticles were successfully doped into β-PbO2 film of PbO2 electrode through composite electrodeposition technology to obtain PbO2/SnO2-CTAB, PbO2/SnO2-SDBS and PbO2/SnO2-SDS electrodes. Physical characterizations, electrochemical measurements and electrocatalytic oxidation of m-nitrophenol (m-NP) were conducted to explore the electrocatalytic activity of prepared electrodes. The results showed that doping SnO2 was favorable to improve electro-catalytic activity of PbO2 electrode, which was attributed to that the SnO2 particles in β-PbO2 films improved the active sites on the surface, oxygen evolution potential and •OH radicals generation rate of the electrodes. The experimental results also revealed that the PbO2/SnO2-CTAB was most efficient in three PbO2/SnO2 electrodes due to the higher zeta potential, smaller particle size and higher specific surface area of SnO2-CTAB than those of SnO2-SDBS and SnO2-SDS. Besides, the accelerated lifetime test shows that the PbO2/SnO2-CTAB electrode possessed longer service lifetime than PbO2/SnO2-SDBS, PbO2/SnO2-SDS and pristine PbO2 electrodes. Overall, the PbO2/SnO2-CTAB electrode is promising for environmental remediation.

Porous carbon (PC) was easily prepared by synthesis of a metal–organic framework (MOF-5) followed by carbonization step. The morphology, structure, Brunauer-Emmett-Teller (BET) surface areas, wettability, and electrochemical performance for PCs carbonized at different temperatures from 500 to 1000 °C were characterized by the techniques of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), N2 adsorption-desorption, contact angle of glycerin, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), and compared with a commercially available activated carbon (AC). The results showed that MOF-5 was fully carbonated at 900 °C, having the highest specific surface area of 1563.09 m2 g−1 and the largest pore volume of 1.07 cm3 g−1. The PC carbonized at 900 °C (PC-900) exhibited better wettability, a higher specific capacity and a lower charge transfer resistance than other PCs and AC. In further capacitive deionization (CDI) process, the PC-900 electrode exhibited 9.39 mg g−1 CDI capacity, significantly higher than 5.47 mg g−1 of AC electrode. More importantly, easy and good repeatability could be obtained for PC-900 electrode. This study suggests that the PC-900 derived from MOF-5 may be a potential electrode material for CDI.

Modification of PbO 2 electrode was carried out by carbon nanotube (CNT) and Ce co-deposition. The surface morphology and crystal structure of CNT and Ce modified PbO 2 (CNT–Ce–PbO 2 ) electrode was characterized by scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) specific surface area, respectively, and compared with pure PbO 2 , Ce–PbO 2 , and CNT–PbO 2 electrodes. The results indicate that the CNT and Ce were both doped into PbO 2 film and the CNT–Ce–PbO 2 electrode had smaller grain size and higher specific surface area than those of other three kinds of electrodes. The electrochemical properties of electrodes were tested by linear sweep voltammetry and cyclic voltammetry, and the results show that the CNT–Ce–PbO 2 electrode had higher electro-catalytic activity than pure PbO 2 , Ce–PbO 2 , and CNT–PbO 2 electrodes. The accelerated lifetime tests demonstrate that the service life of CNT–Ce–PbO 2 electrode was 4.76 times longer than that of pure PbO 2 electrode. The CNT–Ce–PbO 2 electrode was also used in electrochemical degradation of p -nitrophenol ( p -NP) in aqueous solution. The degradation kinetics and mechanism of p -NP were discussed. Besides, the variation of biodegradability of p -NP degradation solution was also investigated, and the results obtained revealed a feasible combination between electrochemical oxidation and conventional bio-treatment for the treatment of p -NP wastewater.

In this paper, we prepared activated carbon (AC) electrodes with AC powder and self-made binder. The surface characteristics of AC electrode were characterized using scan electron microscope, contact angles of droplets, and N2 adsorption–desorption isotherms. The results showed that the AC electrode had favorable hydrophilic property and high specific surface area (717 m2 g−). In addition, the electrosorption kinetics and isotherm of different anions (Cl−, , , and ) on AC electrodes were investigated. The electrosorption of Cl−, , , and, on AC electrodes followed pseudo-first-order kinetics model; the monovalent ion (Cl− and ) had higher electrosorption capacity and electrosorption rate than multivalent ions (, and ), and Freundlich isotherm fitted electrosorption data of monovalent ions while the Langmuir isotherm fitted the experimental data of multivalent ions.

The electrochemical oxidation behavior of 4-Chlorophenol (4-CP) on a vitreous carbon electrode was investigated in acidic (1 M H2SO4, pH 0.4), neutral (1 M Na2SO4, pH 6.9), and alkaline (1 M NaOH, pH 12.0) mediums containing 1–5 mM of 4-CP, at different temperatures between 25 and 85 °C, by cyclic voltammetry technique. The results indicate that the 4-CP was oxidized more easily in alkaline medium than acidic and neutral mediums, and the oxidation peaks of 4-CP shifted toward lower potential values by increasing temperature and 4-CP concentration. Successive scans led to the inactivation of vitreous carbon electrode as a result of the forming of polymeric films whatever the pH, the temperature and the 4-CP concentration used, but the inactivation of electrode surface was more easily induced in neutral and acidic mediums rather than alkaline medium and was retarded significantly when performed at the temperatures higher than 45 °C. Additionally, the 4-CP oxidation process at vitreous carbon electrode was controlled by diffusion except at higher concentration (50, 100 mM) where it is limited by adsorption.

The PbO2 electrode was prepared by electrodeposition method in this paper. The electrode was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The electrochemical oxidation of phenol in aqueous solution was studied by galvanostatic electrolysis using PbO2 electrode as anode. UV spectroscopy, total organic carbon (TOC) and chemical oxygen demand (COD) measurements were conducted to study the kinetics of phenol electrochemical degradation and the mineralization efficiency under different current densities. The experimental results showed that the applied current density had a positive influence on the degradation of phenol and removal of TOC, but a higher current density led to lower current efficiency and higher energy consumption. The phenol degradation always followed a pseudo-first-order kinetics. In addition, aromatic intermediates and general carboxylic acids generated in the degradation of phenol have been indentified using high-performance liquid chromatography (HPLC) and a general pathway for the electrochemical degradation of phenol on PbO2 anode was proposed.

A novel liquid binder, which is called AA in this paper, was synthesized with acrylic acid and azodiisobutyronitrile to prepare electrodes from activated carbon (AC, ACE) for capacitive deionization (CDI). The ACE prepared with AA (ACE-AA) was carbonized to improve its CDI performance. As a result, its wettability was significantly improved, and the specific capacitance was increased by a factor of 8. The optimization showed that electrodes with a mass fraction of AC of 35 wt% had the best CDI performance. Compared with ACEs prepared with phenolic resin (PR), polytetrafluoroethylene (PTFE) and epoxy resin (ER), electrodes prepared using AA binder showed improved flexibility, durability, wettability, and desalination ratio. Therefore, the ACE-AA seems to be a very promising carbon electrode for CDI.

The lauryl benzene sulfonic acid sodium (LAS)-carbon nanotube (CNT)-modified PbO 2 electrode was fabricated by thermal deposition and electrodeposition methods. Its morphology and composition were compared with those of PbO 2 , CNT-PbO 2 , and LAS-PbO 2 electrodes. It was found that CNT could be doped into the PbO 2 film in the presence of LAS. The [Fe(CN) 6 ] 4−/3− redox couple in 0.1 M KCl was used for initial evaluation of the electro-catalytic activity of prepared electrodes. The results showed that LAS-CNT-PbO 2 electrode exhibited the largest peak current and the smallest Δ E p in [Fe(CN) 6 ] 4−/3− redox process. The stability tests showed that the service life of LAS-CNT-PbO 2 electrode was 1.8 times longer than that of PbO 2 electrode. The electro-catalytic activity of the prepared electrodes was also examined for the electrochemical oxidation of 4-chlorophenol (4-CP) and the LAS-CNT-PbO 2 electrode exhibited the highest activity for 4-CP degradation among the four PbO 2 -based electrodes. Besides, HPLC was employed to identify the products resulting from the electrochemical oxidation of 4-CP and the degradation mechanism of 4-CP was also discussed.

In this study, carbon nanotube (CNT) modified PbO 2 electrodes were fabricated using electrodeposition method. The influence of adding cationic surfactant–cetyltrimethylammonium bromide (CTAB) or anionic surfactant–lauryl benzene sulfonic acid sodium (LAS) into electrodeposition solution on the performance of CNT–PbO 2 electrodes was compared. The morphology, elemental composition and phase composition of PbO 2 , CNT–PbO 2 , CTAB–PbO 2 , LAS–PbO 2 , CTAB–CNT–PbO 2 and LAS–CNT–PbO 2 electrodes were characterized using scanning electron microscope (SEM), X-ray energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Linear sweep voltammetry (LV) and cyclic voltammetry (CV) were also utilized to study the electrochemical performance of different electrodes. The results showed that more CNT could be doped into the PbO 2 film by the synergetic action of LAS, and the LAS–CNT–PbO 2 electrode has a higher activity than other PbO 2 -based electrodes. In addition, fluorescence spectrum technique was used to determine the amount of hydroxyl radical produced during the electro-catalytic oxidation process, which gave the direct evidence that the generation capability of hydroxyl radical on the surface of LAS–CNT–PbO 2 was stronger than those of other PbO 2 -based electrodes. Mineralization experiments of 4-chlorophenol (4-CP) also indicated that the electro-catalytic activity of LAS–CNT–PbO 2 electrode was superior to other electrodes. Stability tests at 60 °C and in 2.0 M aqueous H 2 SO 4 with an anodic current density of 1.0 A cm −2 showed that the LAS–CNT–PbO 2 electrode had the highest electrochemical stability.

In this work a carbon nanotube–Ce-modified PbO2 (CNT–Ce–PbO2) electrode was prepared by electrodeposition method, and compared with pure PbO2, Ce–PbO2, and CNT–PbO2 electrodes. The direct and indirect oxidation capacities of prepared electrodes in electro-catalytic oxidation processes were investigated by cyclic voltammetry and hydroxyl radical production tests, respectively. The electro-catalytic activity of electrodes was examined by electro-catalytic oxidation of a model pollutant of m-nitrophenol (m-NP). Besides, high-performance liquid chromatography (HPLC) was also employed to identify the products resulting from the electro-catalytic oxidation of m-NP and the degradation mechanism of m-NP was proposed. Results show that the CNT–Ce–PbO2 anode has higher direct and indirect oxidation capacities than pure PbO2, Ce–PbO2, and CNT–PbO2 anodes. In the electro-catalytic oxidation of m-NP, the m-NP can be oxidized and degraded at all anodes, and the oxidation reactions of m-NP follow first-order kinetics. m-NP and TOC removal efficiencies are about 0.987 and 0.622 after electrolysis of 120 min and a maximum first-order rate constant of 0.036 min−1 is achieved at the CNT–Ce–PbO2 anode, which are obviously higher than those of the other three kinds of anodes. Keywords: Electro-catalytic oxidation, PbO2 electrode, Carbon nanotube, Ce, m-Nitrophenol