Oxygen Evolution Potential Research Articles

Preparation and Electrochemical Performance of the Stainless Steel/α-PbO2-ZrO2/β-PbO2-ZrO2-CNT Composite Anode

A novel stainless steel/α-PbO2-ZrO2/β-PbO2-ZrO2 (30 g l−1)-CNT (10 g l−1) modified by carbon nanotube (CNT) and ZrO2 co-doping was prepared by pulse electrodeposition. The effect of ZrO2 and CNT concentration on the chemical composition, surface morphology, electrocatalytic activity and corrosion resistance of the composite anode materials was studied by anodic polarization curve (LSV), cyclic voltammetry curve (CV), Tafel curve, scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the surface of the electrode modified by CNT (30 g l−1) and ZrO2 (10 g l−1) has a larger active area and smaller crystallite particles. The formed deposit is flat, dense and crack-free. The electrode has more corrosion resistance. Compared with the stainless steel/α-PbO2-ZrO2/β-PbO2 and the stainless steel/α-PbO2-ZrO2/β-PbO2-ZrO2 (30 g l−1) anode, the stainless steel/α-PbO2-ZrO2/β-PbO2-ZrO2 (30 g l−1)-CNT (10 g l−1) anode has a lower oxygen evolution potential, better electrocatalytic activity, and stronger corrosion resistance.

Preparation and electrochemical treatment application of Ti/Sb–SnO2-Eu&rGO electrode in the degradation of clothianidin wastewater

This work investigated the preparation of Ti/Sb–SnO2 electrode co-doped with graphene and europium and the electrochemical degradation of clothianidin in aqueous solution with Ti/Sb–SnO2-Eu&rGO electrode. The physicochemical properties of different electrodes were characterized by using the scanning electron microscopy, X-ray diffraction, oxygen evolution potential and cyclic voltammetry tests. The results indicated that the Ti/Sb–SnO2-Eu&rGO electrodes have a compact structure and fine grain size and have a higher oxygen evolution overpotential than Ti/Sb–SnO2-None, Ti/Sb–SnO2-Eu and Ti/Sb–SnO2-rGO electrodes. Among the four electrodes, the Ti/Sb–SnO2-Eu&rGO electrode showed the highest efficiency and was chosen as the experimental electrode. The main influence factors on the degradation of clothianidin, such as initial pH, electrolyte concentration, current density and initial concentration of clothianidin, were analyzed. The results showed that the removal rate of clothianidin can reach 96.44% under the optimal conditions for 120 min treatment. Moreover, a possible degradation pathway including the fracture of internal bonds of clothianidin such as the N–N bond, the C–N bond that connects nitroguanidine to the thiazole ring and mineralization was elucidated by intermediate products identified by HPLC-MS method and Fourier transform infrared spectroscopy (FTIR). This paper introduces the Ti/Sb–SnO2-Eu&rGO electrode into an electrocatalytic degradation system and could provide basic data and technique support and guidance for the clothianidin wastewater pollution control.

A study on the effect of introducing S-doped GO into the active layer on the performance of wire mesh Ti/Ce-Mn/SnO2-Sb-La electrodes

This study aims to investigate the influence of the introduction of S-doped GO in the active layer on the performance of wire mesh Ti/Ce-Mn/SnO2-Sb-La electrodes, Ti/Ce-Mn/SnO2-Sb-La electrodes, Ti/Ce-Mn/SnO2-Sb-La-rGO electrodes and Ti/Ce-Mn/SnO2-Sb-La-S-rGO electrodes, based on the wire mesh titanium. These were prepared and compared by sol-gel and thermal oxidation. Compared with the wire mesh Ti/Ce-Mn/SnO2-Sb-La electrode, the results of experiment indicated that the electrode prepared by introducing S-doped GO into the active layer has a higher electrochemical performance, and that the oxygen evolution potential increased from 1.78 V to 2.12 V. Within 120 min, the degradation efficiency of phenol increased from 75.2% to 89.5%, and the mechanism of the electrocatalytic degradation of phenol was revealed. At the same time, the removal rate of COD increased from 65.5% to 79.8%. During the degradation of phenol, the tank voltage remained stable at a minimum of 4.6 V. The accelerated life experiments revealed that the electrode prepared by introducing S-doped GO into the active layer had an accelerated life of 1.5 times, when compared to the electrode prepared without any introduction, up to 2.73 h. Therefore, the introduction of S-doped GO in the active layer can effectively improve the performance and service life of electrodes.

A novel electrodeposited sandwich electrode with an efficient performance in complex water treatment

The use of an electrocatalytic surface coating is important in environmental remediation using electrochemistry. In this work, a novel Ti/calcined graphene (CG)/PbO2 sandwich electrode was successfully fabricated by a simple electrodeposition strategy for the efficient electrocatalytic oxidation of dye wastewater. The Ti/CG/PbO2 electrode coating was uniform and the structure was compact. As the electrocatalyst was rich in graphene, the novel electrode possessed higher oxygen evolution potential, lower charge transfer resistance, stronger stability, longer service life and higher instantaneous current efficiency (ICE) compared with traditional Ti/PbO2 electrode, thus exhibited better electrocatalytic oxidation activity and mineralization capacity. At a current density of 50 mA/cm2, up to 30 mg/L of methylene blue (MB) was almost completely oxidized in 1 h, while the MB removal efficiency at the Ti/PbO2 electrode only reached 78.2 ± 0.01%. Various influencing factors were designed to simulate the changes of the wastewater system, importantly and interestingly, the electrode still owned the advantages of high-efficiency electrocatalytic oxidation in the complex changes of a wastewater system like pH range of 3–11 and various electrolyte concentrations. The as-prepared electrode could still maintain good degradation efficiency after 30 cycles. It was worth mentioning that the COD value was reduced to about 0 when using this electrode to deal with the actual printing and dyeing wastewater. The results showed that the Ti/CG/PbO2 electrode was promising in the degradation of pollutants.

Spinel CuxCo1−xMn2O4 electrode for effectively cleaning organic wastewater via electrocatalytic oxidation

Development of anodes with high electrocatalytic activity, electrochemical stability and low cost is a key to clean organic wastewater via electrocatalytic oxidation. Here, spinel CuxCo1−xMn2O4 (CCM-X) was prepared by introducing copper with high catalytic activity into the structurally stable spinel CoMn2O4. The CCM-X were coated on the surface of titanium plate and used as anodes to study their electrocatalytic oxidation performance for cleaning simulated organic wastewater (tetracycline hydrochloride aqueous solution). The maximum removal ratio of 20 mg L−1 tetracycline hydrochloride was 91.3% in 120 min and still reached 84.9% after 5-times’ reusing of the anode, which was attributed to the high electrocatalytic activity, oxygen evolution potential (1.70 V vs. Ag/AgCl) and stable structure of multi-metal oxide CCM-X anode. In addition, free radical trapping experiments showed that hydroxyl radicals played a major role in electrocatalytic oxidation process. Electrochemical tests showed that redox of Co(III)/Co(IV) and Mn(III)/Mn(IV) participated in the electrocatalytic oxidation reaction, and doping Cu can effectively improve the electron transfer ability and electrocatalytic activity of CCM-X. Therefore, CCM-X/Ti electrodes perform attractive application prospects in cleaning organic wastewater via electrocatalytic oxidation.

Co/Sm-modified Ti/PbO2 anode for atrazine degradation: Effective electrocatalytic performance and degradation mechanism

In this work, Ti/PbO2–Co-Sm electrode has been successfully prepared using electrodeposition and further applied for the electrocatalysis of atrazine (ATZ) herbicide wastewater. As expected, Ti/PbO2–Co-Sm electrode displays highest oxygen evolution potential, lowest charge transfer resistance, longest service lifetime and most effective electrocatalytic activity compared with Ti/PbO2, Ti/PbO2-Sm and Ti/PbO2–Co electrodes. Orthogonal and single factor experiments are designed to optimize the condition of ATZ degradation. The maximum degradation efficiency of 92.6% and COD removal efficiency of 84.5% are achieved in electrolysis time 3 h under the optimum condition (current density 20 mA cm−2, Na2SO4 concentration 8.0 g L−1, pH 5 and temperature 35 °C). In addition, Ti/PbO2–Co-Sm electrode exhibits admirable recyclability in degradation progress. The degradation of ATZ is accomplished by indirect electrochemical oxidation and ∙OH is tested as the main active substance in ATZ oxidation. The possible degradation mechanism of ATZ has been proposed according to the degradation intermediates detected by LC-MS. This research suggests that Ti/PbO2–Co-Sm is a promising electrode for ATZ degradation.

NiFe hydroxide pillared by metaborate for efficient oxygen evolution reaction

Water-splitting by electrolysis is one of the most important approaches to produce hydrogen as renewable clean energy with superior advantages of high-purity and good operability. But the key issue limiting the large-scale application is that it demands a much higher overpotential than the theoretical oxygen evolution potential. Herein, we report an efficient electrochemical catalyst of NiFeBO synthesized via a facile one-step process, presenting remarkable catalytic activity and long-term stability. In this work, we discussed the effects of the doping of Fe and the insertion of BO2− in the as-synthesized NiFeBO. According to the experimental results, NiFeBO shows a very low overpotential of 256 mV and a Tafel slope of 53 mV dec−1 with remarkable stability over 60 h of chronopotentiometry test. The inserted anion of BO2− can adsorb OH− in electrolyte around the catalyst to increase the concentration of OH− around the active sites, thereby improving the effectivity of oxygen evolution reaction. In addition, diffused micro-crystalline with different lattice formed during the oxidation of the as-synthesized catalyst, providing more active sites than the pristine amorphous.

High Efficiency Electrochemical Degradation of Phenol Using a Ti/PbO2-Bi-PTh Composite Electrode

A novel Ti/PbO2-Bi-PTh composite electrode was successfully prepared by electrodeposition and applied in electrochemical degradation of phenol. The Ti/PbO2-Bi-PTh electrode was characterized by XRD, SEM, AFM, LSV, CV and EIS. Results showd that the electrode has a fine and compact surface structure, higher oxygen evolution potential (OEP, 2.42 V) and low charge transfer resistance (51.00 Ω). The electrode also exhibited excellent electrochemical oxidation activity on the degradation of phenol (1000 mg l−1) with degradation efficiency of 100% and TOC removal rate of 93.58% achieved in 60 min and 180 min, respectively. In addition, possible mechanism of phenol degradation on the electrode was proposed by analyzing the intermediate products with GC-MS. Noticeably, the Ti/PbO2-Bi-PTh electrode displayed excellent stability and high electrocatalytic performance after 10 cycles, indicating its promising application in the phenolic wastewater treatment.

Electrochemical Degradation of Pharmaceuticals Using Ti/SnO2-Sb2O5-IrO2-RuO2 Anode: Electrode Properties, Performance and Contributions of Diverse Reactive Species

Non-biodegradable pharmaceuticals are a group of emerging contaminants that have gained much attention because of their potential risk of inducing adverse ecological and health effects. An efficient Ti/SnO2-Sb2O5-IrO2-RuO2 electrode was prepared by Pechini method and employed as the anode for electrochemical degradation of selected pharmaceuticals (i.e., ibuprofen, atenolol, and carbamazepine). Compared its counterparts, Ti/SnO2-Sb2O5-IrO2-RuO2 exhibited higher oxygen evolution potential, lower chlorine evolution potential, larger active area, and higher stability. Unlike the negligible effect of solution pH from 4.0 to 10.0, increasing current density favored the target pollutants and COD removal. The removal of IBU was mainly attributed to the reaction with •OH, the contribution of which to IBU removal was enhanced with increasing current density. In contrast to IBU, the removal of ATEN and CBZ was mainly ascribed to the reaction with selective radical chlorine species (RCS) mainly in the form of Cl•, which was produced from direct oxidation of Cl− or indirect oxidation by •OH. It was found that the removal of ATEN and CBZ was less affected by dissolved organic matter (DOM) than that of IBU in municipal effluent. This study demonstrates that Ti/SnO2-Sb-RuO2-IrO2 is an attractive electrode for the destruction of pharmaceutical contaminants.

Tin dioxide decorated on Ni-encapsulated nitrogen-doped carbon nanotubes for anodic electrolysis and persulfate activation to degrade cephalexin: Mineralization and degradation pathway

In this study, bamboo-shaped carbon nanotubes exhibiting high nitrogen content and Ni encapsulation (Ni@NCNT) were effectively synthesized by a simple pyrolysis method. The catalytic peroxydisulfate activation for cephalexin (CPX) degradation was investigated using the prepared material. SnO2 was further decorated and fabricated on the anode material (SnO2/Ni@NCNT) for electrochemical degradation of CPX in an aqueous solution. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that the SnO2 nanoparticles were uniformly distributed on the surface of Ni@NCNT. Electrochemical characterization employing cyclic voltammetry and linear sweep voltammetry demonstrated that SnO2/Ni@NCNT displayed higher oxygen evolution potential and electrocatalytic activity than Ni@NCNT. Mineralization of CPX in wastewater was performed using electrolysis coupled with persulfate oxidation. The analysis revealed a synergistic strengthening effect. The electropersulfate oxidation resulted in higher total organic carbon (TOC) removal (70.3%) than the sum of electrooxidation (48.1%) and persulfate oxidation (9.2%) toward CPX. This phenomenon might result from the regeneration of sulfate radicals (SO4•−) on the anode and complementary oxidation by SO4•− and OH. Persulfate oxidation alone was shown to result in low TOC removal, although CPX was mostly degraded. Additionally, the CPX degradation pathway involving electropersulfate oxidation was proposed and it is indicated that CPX molecules were completed decomposed by the examination of short chain acids, mineralized ions, and ecotoxicity evolution indicated that the antibiotic was completely degraded. This study provides a new approach for the design and preparation of novel electrode materials and electrochemical degradation facilities for the removal of pollutants via persulfate activation.

Anodic oxidation of ciprofloxacin using different graphite felt anodes: Kinetics and degradation pathways

Ciprofloxacin (CIP) is ubiquitous in the environment which poses a certain threat to human and ecology. In this investigation, the physical and electrochemical properties of graphite felt (GF) anodes which affected the anodic oxidation (AO) performance, and the CIP removal effect of GF were evaluated. The GFs were used as anodes for detection of ·OH with coumarin (COU) as molecule probe and removal of CIP in a 150 mL electrolytic cell with Pt cathode (AO-GF/Pt system). The results showed that hydrophilic GF (B-GF) owned higher sp3/sp2 and more oxygen-containing and nitrogen-containing functional groups than the hydrophobic GF (A-GF). Moreover, B-GF possessed higher oxygen evolution potential (1.12 V), more active sites and stronger ·OH generation capacity. Above mentioned caused that B-GF exhibited more superior properties for CIP removal. The best efficiencies (96.95%, 99.83%) were obtained in the AO-B-GF/Pt system at 6.25 mAcm−2 after 10 min (k1, 0.356 min−1) and 60 min (k2, 0.224 min−1), respectively. Furthermore, nine degradation pathways of CIP in AO-B-GF/Pt system were summarized as the cleavage of the piperazine ring, cyclopropyl group, quinolone ring and F atom by ·OH. It provides new insights into the removal and degradation pathways of CIP with GF in AO system.

Electrochemical oxidation of aniline using Ti/RuO2-SnO2 and Ti/RuO2-IrO2 as anode

Electrocatalytic properties of anode and the electrolyte composition are important parameters influence the degradation efficiency for aniline wastewater. Ti/RuO2-SnO2 and Ti/RuO2-IrO2 have been fabricated using thermal decomposition method and experiments in electrolyte containing 0.05 M Na2SO4, 0.05 M NaCl and 0.05 M Na2SO4+0.005 M FeSO4 at different current density were conducted to study the influence on aniline degradation. Linear sweep voltammetry (LSV) showed that Ti/RuO2-SnO2 had higher oxygen evolution potential and degrade aniline through electrochemical transformation and electrochemical combustion while Ti/RuO2-IrO2 degrade aniline mainly through electrochemical transformation. The study showed that Ti/RuO2-SnO2 had higher electrocatalytic activity towards the degradation of aniline than Ti/RuO2-IrO2 anode in 0.05 M Na2SO4 and in 0.05 M NaCl electrolyte. The maximum TOC removal efficiency for Ti/RuO2-SnO2 was 64.2% at 40 mA cm−2 in Na2SO4 electrolyte while the average MCE was 1.6% and the average ECTOC was 1.51 kWh (g TOC)−1. On the contrary, the maximum TOC removal efficiency for Ti/RuO2-IrO2 was 63.1% at 40 mA cm−2 in NaCl electrolyte while the average MCE was 1.6% and the average ECTOC was 1.95 kWh (g TOC)−1. The presence of Fe2+ in Na2SO4 electrolyte would decrease the TOC removal efficiency except at low current density (20 mA cm−2) for Ti/RuO2-SnO2. These results indicated that Ti/RuO2-SnO2 and Ti/RuO2-IrO2 anode were suitable in Na2SO4 and NaCl electrolyte, respectively, while the presence of Fe2+ would inhibit aniline degradation.

The preparation of black titanium oxide nanoarray via coking fluorinated wastewater and application on coking wastewater treatment

Coking wastewater is extremely toxic with poor biodegradability owing to the presence of refractory organics. Black titanium oxide nanotube array (BTN), not only photocatalyst but also electrocatalyst, is with definite potentiality in organic wastewater treatment. Here, we firstly developed an electrochemical method, using fluorinated coking wastewater as electrolyte rather than traditional fluorinated ethylene glycol, to prepare titanium oxide nanoarray economically. Unexpectedly, suspended pollutants and ammonia nitrogen in coking wastewater were removed in BTN preparation. Moreover, the as-prepared BTN could be further employed as photocatalyst or electrocatalyst to degrade dissolved organic matter in coking wastewater. As an electrocatalyst, BTN possessed the comparable •OH production activity about 9.9 × 10−15 M S−1 to boron-doped diamond, high oxygen evolution potential around 2.75 V, and high selectivity of chlorine production. Moreover, the biodegradability of treated coking wastewater could be effectively improved by using BTN as electrocatalyst in electrochemical oxidation, and the BOD/COD was from 0.19 to above 0.3 in 4 h at current density of 2 mA cm−2. The energy consumption was about 63–68 kWh kgCOD−1, lower than that of various reported electrodes. This study provided an economical and environmentally friendly method to prepare BTN, which was with positive application prospect in the field of coking wastewater treatment.

Effect of Pb(NO3)2 on Preparation and Properties of CF/β-PbO2 Electrodes for Zinc Electrowinning

In this study, the β-PbO2 active layer was deposited on the surface of the carbon fiber cloth by electrodeposition. The CF/β-PbO2 electrode was investigated by scanning electron microscopy (SEM), anodic polarization curves, Tafel curves, and a four-probe method. It was found that a uniform and flattened dense β-PbO2 active layer is obtained when the concentration of Pb(NO3)2 is 150 g l−1. The deposition quality of the active layer of β-PbO2 particles in the carbon fiber is affected by the concentration of Pb(NO3)2, thereby affecting the interfacial bonding strength between the active layer and the carbon fiber. The weightlessness rate of the carbon fiber substrate electrode materials with Pb(NO3)2 concentration of 150 g l−1 are the smallest. The interface resistivity of the CF/β-PbO2 electrode sample with Pb(NO3)2 concentration of 150 g l−1 is 6.71 × 10−5 Ω·m and is smallest. The CF/β-PbO2 electrode prepared under the 150 g l−1 has the smallest oxygen evolution potential and is 2.335 V. When the concentration of Pb(NO3)2 is 150 g l−1, the prepared CF/β-PbO2 electrode has the largest corrosion potential (1.085 V) and the minimum corrosion current (2.074 × 10−4 A · cm−2).

Theoretical investigation of CoTa2O6/graphene heterojunctions for oxygen evolution reaction

Water electrolysis is to split water into hydrogen and oxygen using electricity as the driving force. To obtain low-cost hydrogen in a large scale, it is critical to develop electrocatalysts based on earth abundant elements with a high efficiency. This computational work started with Cobalt on CoTa2O6 surface as the active site, CoTa2O6/Graphene heterojunctions have been explored as potential oxygen evolution reaction (OER) catalysts through density functional theory (DFT). We demonstrated that the electron transfer (δ) from CoTa2O6 to graphene substrate can be utilized to boost the reactivity of Co-site, leading to an OER overpotential as low as 0.30 V when N-doped graphene is employed. Our findings offer novel design of heterojunctions as high performance OER catalysts.

Understanding enhanced charge storage of phosphorus-functionalized graphene in aqueous acidic electrolytes

ABSTRACT The mechanisms behind enhanced charge storage of P-functionalized carbons are unraveled for the first time using non-porous graphene oxide treated with phosphoric acid and annealed at either 400 or 800 °C. The electrochemical study in 1 M H2SO4 reveals that phosphorus groups boost charge storage and electrochemical stability, with more effect for the higher annealing temperature. Annealing at 800 °C also leads to the material withstanding 60,000 charge-discharge cycles with no capacitance loss at 1.5 V. The improvement in the electrochemical performance is shown to be mainly governed by the change in surface chemistry comprehensively studied with NMR, FTIR and XPS characterization techniques. The collective analysis of electrochemical response and surface chemistry demonstrates that enhanced charge storage by phosphorus-functionalized graphene materials is made possible due to the following synergistic mechanisms: i) non-Faradaic charging; ii) nascent hydrogen storage in the interlayer; iii) benzoquinone-to-hydroquinone redox processes; iv) phosphate-to-phosphonate like transformation. From the practical perspective, the stored charge can be boosted due to the higher capacitance upon prior electrochemical activation in the vicinity of oxygen evolution potential and the wider usable electrochemical window enabled by phosphorus-related groups.

Efficient Technique for Simultaneous Lead Recovery and PbO₂/Ti Electrode Preparation for Electrocatalytic Degradation of Basic Red.

In order to achieve the effective removal of Pb2+ from low-concentration wastewater as well as the lead recovery for direct reuse simultaneously, a simple electrodeposition method was used in this study. In this process, synthetic lead wastewater with low concentration of 4, 8, 12 and 16 mg/L was treated, more than 67% lead was recovered from wastewater and a PbO₂/Ti electrode was fabricated in a simple reaction tank. The test results of characterizations confirmed that PbO₂ nanoeletrocatalyst was successfully deposited on a Ti substrate. Electrochemical activity tests indicated that PbO₂/Ti electrode had advantages of high oxygen evolution potential (1.90 V) and low electron transfer resistance. Furthermore, the results of electrocatalytic degradation experiments demonstrated that prepared PbO₂/Ti electrode had the superb decolorization and mineralization ability on Basic Red. After 120 min of electrolysis, the Basic Red removal efficiency and TOC removal efficiency could reach to 89.38% and 68.82%, respectively, which was 5.2 and 7.1 times higher than the Ti substrate alone. Besides, the calculated mineralization current efficiency for PbO₂/Ti electrode increased from 5.18% to 36.74% after PbO₂ depositing, and thus an economical benefit was obtained by more than 5 times energy saving. The influences of the applied current density, initial dye concentration, electrolyte concentration and solution pH on the oxidation efficiency were also investigated and optimized. The prepared PbO₂/Ti electrode also showed a great stability with high dye removal efficiency (above 85%) after 10 times repeated experiments. These results suggest that it is a promising technological process to remove and recover lead from low-concentration wastewater efficiently and reuse them as electrocatalyst for other organic wastewater treatments.

Degradation Pathway and Kinetics of 4-chlorphenol by Sn/Sb-Mn-GAC Composite Particle Electrode

A composite particle electrode Sn/Sb-Mn-GAC was prepared by impregnation with granular activated carbon (GAC) as carrier. The surface morphology, phase composition and electrochemical properties of the particle electrode were characterized by scanning electron microscopy, X-ray diffraction and electrochemical workstation. The results show that the Sn/Sb-Mn-GAC particles have uniform grain size, good dispersity and high oxygen evolution potential. The Sn/Sb-Mn-GAC particle electrode was used to the electrochemical degradation of 4-chlorophenol. It was shown that 4-chlorophenol was almost completely removed after electrolyzing for 60 min. A large number of intermediates were produced during the degradation of 4-chlorophenol in the experimental system. The main intermediate products were benzoquinone, 4-chlorocatechol, hydroquinone, fumaric acid, oxalic acid, etc., eventually mineralized into water and carbon dioxide. The degradation pathway of 4-chlorophenol were preliminarily suggested through the analysis of intermediates in degradation process. The supported Sn/Sb-Mn-GAC particle electrode can be repeated used 4 times in three-dimensional electrochemical reactor and the kinetic model for the electrochemical oxidation of 4-chlorophenol was established. The experimental results show that the degradation process of 4-chlorophenol accords with the first-order kinetic model, the correlation coefficient is 0.98 or more. The kinetic rate constant k of Sn/Sb-Mn-GAC particle electrode is reduced when it is repeated used, but the treatment efficiency of 4-chlorophenol is still better. The results of research show that the three-dimensional electrochemical reactor using Sn/Sb-Mn-GAC particle electrode has promising application prospects in the treatment of phenolic wastewater.

A novel Pb/PbO2 electrodes prepared by the method of thermal oxidation-electrochemical oxidation: Characteristic and electrocatalytic oxidation performance

The PbO2 electrodes were preservative and chemically stable but had the problem of the poor electrocatalytic oxidation activity and instability. In this research, Pb/PbO2 electrodes with good electrocatalytic oxidation activity and stability were prepared via a novel combined method of thermal oxidation and electrochemical oxidation, which was different form electrodeposition and coating method. Combined with the results analyzed by SEM, metallographic microscope, XRD, steady-state polarization and CV tests, the electrocatalytic oxidation performance was evaluated by the generation capacity of ·OH and the removal efficiency of Congo red (CR). The experimental results put in evidence that the electrochemical oxidation time affected the electrochemical oxidation performance of Pb/PbO2 electrode by refinement of crystal sizes and strengthening of crystallinity which promoted oxygen evolution potential and ·OH generation ability. The better ·OH generation ability of 6-PbO2 encouraged the removal of CR (68.62%, 0.177 min−1) whose chromophore and ring structure of aromatic hydrocarbons was destroyed by ·OH (7.82 × 10−4 μM min−1) with initial concentration of 20 mg·L-1 at 8 mA·cm-2 for 20 min. Moreover, 6-PbO2 owned stability for its compact surface. It showed that the stable 6-PbO2 electrode prepared by the thermal oxidation-electrochemical oxidation method had good electrocatalytic oxidation activity and excellent application potential, which were worthy of further research.

Nanostructured amorphous Fe29Co27Ni23Si9B12 high-entropy-alloy: an efficient electrocatalyst for oxygen evolution reaction

Proximal configuration of dissimilar metal atoms in amorphous high-entropy-alloys (HEAs) always result in interatomic d-band ligand effect, dense defect distribution, coordinatively unsaturated sites, high potential energy, and loose atom bonding. Herein, nanostructured amorphous Fe29Co27Ni23Si9B12 HEA ribbon is fabricated via a melt spinning method combined with electrochemical corrosion etching process, which is applied as the potential oxygen evolution reaction electrocatalyst. It is found that there are micro/nano pits on the surface of etched amorphous Fe29Co27Ni23Si9B12 ribbons. Various elements of HEAs bond with each other to form a highly disordered configuration, which could result in an optimized bonding energy and enhanced intrinsic catalytic activity. The electrocatalysis activity measurements indicate that the amorphous HEA endows a much higher activity than the crystalline one, which is further improved by the electrochemical etching treatment. Especially, the HEA ribbon etched for 3 h requires a low overpotential of 230 mV to afford 10 mA cm-2 current density. In addition, density functional theory calculations demonstrate that the amorphous structure can weaken the interaction between the surface of Fe29Co27Ni23Si9B12 alloy and the intermediates, leading to an optimized adsorption Gibbs free energy.