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In the presence of magnetic field, reducing the loss in temperature coefficient of resistance (TCR) and increasing metal−insulator transition point (TMI) to room temperature are the most important concerns for the application of perovskite manganites in high−precision thermistors. Based on emerging evidence, relevant factor to address these problems lies in the interaction between Jahn−Teller (JT) distortion and magnetic field, which results in spin−orbital coupling (SOC) effect and significantly influences TCR and TMI. In this work, we studied the magnetic field induced SOC effect in polycrystalline La1−xCaxMnO3 (x = 0.225–0.45) materials synthesized via sol−gel technique. Compounds undergo the JT distortions with increasing Ca dopant content, and the most pronounced distortion of 0.0144 at x = 0.40 is correlated with a basal−plane distortion mode. All samples exhibit TMI values between 262 K and 288 K, indicating the enhancement of doping−induced double−exchange interaction. In the magnetic field of 1 T, SOC effect sufficiently suppresses the deterioration of TCR caused by deficient magnetization in La0.6Ca0.4MnO3 to a value of 2.9%·K−1 at room temperature (287 K).

High oxygen evolution overpotential and low corrosion resistance are the main challenges for oxygen evolution materials in acidic media. In this study, a novel composite material, Ti/TiO2-NTs/PbO2–CNTs–MnO2, with high oxygen evolution electrocatalytic activity was successfully prepared. First, TiO2 nanotubes (TiO2-NTs) were synthesized in situ on a Ti sheet via anodization and used as an intermediate layer. Subsequently, the adhesion and conductivity of the TiO2-NTs layer were increased through additional anodization, annealing, and electrochemical reduction. Finally, PbO2 was electrodeposited with a constant current in a lead acetate medium and doped with carbon nanotubes (CNTs) and MnO2. The surface morphology, phase composition, and electrochemical performance of the composite materials were investigated. Notably, in an acidic electrolyte (150 g/L H2SO4), Ti/TiO2-NTs/PbO2–CNTs–MnO2 exhibited good stability (30 h) and a low oxygen evolution overpotential of 410 mV at 50 mA/cm2, which is almost equivalent to that of precious metals (RuO2 and IrO2) and 499 mV lower than that of the industrial Pb–0.76 wt% Ag alloy. The outstanding performance is mainly attributed to the high aspect ratio of the TiO2-NT structure, synergistic effects of the active particles, and inherently good electrochemical properties of the active particles. Therefore, this study provides a new synthetic route for oxygen evolution materials in acidic media.

The polycrystalline La1−xCaxMnO3 ceramics exhibit good electromagnetic performance, i.e., high temperature coefficient of resistivity (TCR), which can be tuned flexibly with respect to structures. Unfortunately, the magnetic field applied to these materials causes a massive decrease in TCR, which hinders their practical applications. In this study, polycrystalline ceramic La1−xCaxMnO3:Ag0.2 was fabricated by sol–gel and solid–phase doping methods, and subsequently vast TCR was obtained in the magnetic field for ceramic with x = 0.2. For this polycrystalline material, high value of TCR (58.65%·K−1, 62.00%·K−1) could be maintained with or without magnetic field with metal–insulator (M − I) transition temperature near room temperature range. Extremely high value of TCR in the presence of magnetic field is attributed to the spin–spin coupling effect, which is beneficial to the sensitivity of M − I transition, generating vast TCR in the magnetic field. Overall, these findings provide new prospects for future applications in infrared bolometers.

In the present work, a novel Pb-0.6%Sb/α-PbO2/β-PbO2 composite electrode with quantitatively phases of α or β-PbO2 was obtained by electrodeposition in methanesulfonic acid (MSA) and further investigated in novel flow battery. The physicochemical properties of lead dioxide were analyzed by anodic polarization curves, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and Tafel curves. Results showed that the selection of temperature ranges was found to cause a quantitative difference in the formation of α/β-PbO2 phases, as it made interval effects on the overpotential that was the primary control condition to affect transfer proces.The precise conditions of obtaining α or β-PbO2 phases by varying temperatures were confirmed and samples were prepared to be tested in long-period galvanostatic electrolysis. By comparing, the electrode (deposition time-α&β: 2 h&2 h) showed the best physicochemical properties, which could effectively improve the energy storage and extend the lifetime (63.6 h) compared with the traditional lead dioxide electrodes (24.5 h) in novel flow battery.

To further improve the capability of fault identification for protection and adaptive reclosing, a fault identification scheme based on a control and protection coordination strategy for a hybrid multi-terminal HVDC system is proposed. The protection principle for fault isolation is constructed based on the difference of the polarity characteristic of fault current between the fault line and non-fault line in the uncontrolled fault stage and fault current limiting stage. In the adaptive reclosing stage, an active fault identification scheme based on the amplitude distribution law of the injection signal along the line is proposed. Intensive simulation studies prove the fault identification scheme can identify the fault area in various fault scenarios and identify permanent faults to carry out adaptive reclosing.

Transition metal hydroxides, due to their low cost and high theoretical capacity, are promising candidates for supercapacitors. However, the lower conductivity of hydroxides usually results in devices exhibiting poor specific capacity. Here, Ni(OH)2@Ni12P5 electrodes are designed and prepared, showing great potential for applications. This composite electrode, prepared by simple phosphating treatment and electrodeposition. Compared with the Ni(OH)2 prepared by direct deposition, this rationally designed electrode exhibits more excellent electrochemical properties. The prepared Ni(OH)2@Ni12P5 electrode exhibits a good area specific capacitance of 15.89 F•cm−2 at a current density of 10 mA•cm−2, which is 2.93 times higher than that of the Ni(OH)2 electrode (5.43 F•cm−2). In addition, the assembled Ni(OH)2@Ni12P5//AC asymmetric supercapacitor exhibits an energy density of 0.38 mWh•cm−2 at a power density of 8.00 mW•cm−2 . Therefore, this work provides a new strategy for the synthesis of high-performance supercapacitor electrodes.

A series of Ce1-xFexO2-δ (0 ≤ x ≤ 0.4) catalysts were prepared by a co-precipitation method, and their catalytic activity towards CH4 combustion were investigated. The in situ Raman technology was used to identify the role of oxygen vacancy and the structure evolution of catalysts. The physicochemical characterizations suggest that pure Ce–Fe–O solid solution is formed for the samples with relatively low Fe content (x ≤ 0.3). When further increasing Fe content, free Fe2O3 nanoparticles are detected. The Ce0.6Fe0.4O2-δ catalyst displays the best activity due to the dominated role of free Fe2O3 nanoparticles. However, the Ce0.6Fe0.4O2-δ catalyst is more sensitive to the space velocity, and higher space velocity significantly reduces the activity, owing to the low concentration of oxygen vacancies. It is also found that the activity of Ce0.6Fe0.4O2-δ catalyst continuously decreases during the long-term testing due to the growth of surface Fe2O3 particles. The in situ Raman experiment suggests that the oxygen vacancy concentration decreases with reaction temperature. The comparison on the evolution of Raman spectra under different atmospheres indicates a possible reaction mechanism: the methane firstly adsorbs and reacts with the reducible species (e.g., free Fe2O3 clusters or surface oxygen species) on catalyst, and then the gas phase oxygen replenishes the defects (i.e., reduced iron species or oxygen vacancies) to close the redox process.

Sn-SbOx, Sn-Sb-RuOx, and β-PbO2 coatings were successfully deposited on a titanium substrate by using the thermal deposition and electrodeposition methods, and their electrochemical properties were investigated in detail. The Sn-Sb-RuOx interlayer played a very important role in enhancing the stability of the PbO2 coating electrodeposited at a low current density. The scanning electron microscopy results showed that the cracks in the Sn-Sb-RuOx coating were larger than those in the Sn-SbOx coating. Moreover, the Ti/Sn-Sb-RuOx/β-PbO2 coating had many large pits with pore diameters in the range of 50–180 μm and pore depths of

Due to the special fault features of the inverter-interfaced system, traditional phase selectors exist adaptability problems. In this paper, a novel voltage phase selector based on a two-stage control strategy is proposed, which is not influenced by the special features of the converter. First, the fault features of the converter during fault ride through (FRT) operation are analyzed. Second, using the high controlled-ability of the converter, the control strategy is divided into two stages by adding disturbances to the power references of the control system at the second control stage. On this basis, a novel superimposed sequence network is defined as the subtraction of the compound sequence networks under the first and the second control stage. Then, the phase-angle differences of sequence voltages in the novel superimposed sequence network are analyzed, which are not influenced by the fault features of the converter and can be used to establish phase selection criteria. The simulation results show that the proposed phase selection scheme is immune to the fault features of the converter system, fault resistance, fault location and the operation modes of the remote end system.

Perovskite manganite La1−yCayMnO3 has giant and tunable magnetoresistance (MR) and anisotropic magnetoresistance (AMR), still the following two challenges are of great concern: (i) large magnetic field is required for achieving excellent electromagnetic performance; and (ii) metal–insulator (M–I) transition temperature (TMI) significantly different from room temperature; both these factors limit its practical applications. In this study, polycrystalline La0.7Ca0.3MnO3:Agx composites were fabricated by sol–gel and solid–phase addition methods, and large MR and AMR (84.1% and 32%, respectively) were obtained at near room temperature in 1 T magnetic field when x = 0.2. Evidently, it was found that the grain boundary scattering effects were weakened due to Ag−addition, which resulted in an enhancement of MR. The tremendously high AMR value was attributed to the anisotropic spin–orbit coupling (SOC) effect. The electron–scattering and small–polaron hopping models were used to successfully fit the resistivity data, which support the SOC effect under different magnetic fields that enhance the AMR. These results support further development of the perovskite manganese oxide with potential applications in manganite devices.

Effective fault identification scheme plays an important role in the fault isolation stage and system recovery stage of multi-terminal DC grid. Therefore, an active detection based single-end DC fault identification scheme is proposed to improve the reliability and sensitivity of fault identification. The control strategy is suggested of the generation of sinusoidal signals at different frequencies by the hybrid modular multilevel converters. Based on the blocking effect of the fault branch on the injection signal, by introducing the improved correlation discrimination algorithm, a single-end fault identification scheme is proposed by using the amplitude difference between the measured and calculated values of injection signals. The proposed scheme can be used for fault isolation and adaptive system recovery. Intensive simulation studies prove the improved sensitivity, and reliability of the proposed scheme for the full length of transmission line without relying on DC boundary. Moreover, the scheme can identify the permanent fault during the system recovery stage.

In industrial zinc electrowinning, the anodic oxygen evolution reaction (OER) has sluggish kinetics leading to ultrahigh overpotential and energy consumption. Herein, a sandwich-like MnCo2O4 modifying PbO2 composite electrode was fabricated via chemical-bath-deposition and electrodeposition. Consequently, the synthesized PbO2 electrode exhibits low Tafel slope of 0.17 V per decade and an operating potential of 1.68 V vs. SCE for 500 A m−2 in a simulated solution containing 150 g L−1 H2SO4 and 50 g L−1 Zn2+. Compared with traditional Pb-0.76Ag alloy, the overpotential at 500 A m−2 decreased by 357 mV, which ascribe to the incorporation of MnCo2O4 minoring crystal grain size and charge transfer resistance and enlarging active surface area. Furthermore, the composite electrode shows robust durability as long as 95 h at 15,000 A m−2 in 0.5 M H2SO4 electrolyte. Hence, this study offers a facile synthesis route to prepare composite electrodes for zinc electrowinning and provides deep insight into the relationship among modifying substances, microstructures, and electrocatalytic activity.

In this study, a nanoscale 3D porous structure is rapidly synthesized on the surface of a Zr-based BMG by dealloying in solutions containing Cl− and F−. The influence of the porous surface structure the electrolyte on the preparation of the porous surface structure is studied. The Zr-based BMG is more likely to be passivated when F− is added to the HCl solution. The corrosion potential gap between the five components in the alloy increases after the addition of F−. The phase transformation and structure formation of a Zr-based BMG during dealloying are studied. The main dissolved elements in the dealloying process are Zr, Ti, and Al. Cu10Zr7, Zr2Ni7 and AlTi3 are the main crystal phases after dealloying, but the Zr-based BMG remains dominated by amorphous phases. The formation of the porous structure can be divided into two stages, the pitting corrosion process and the dealloying process, and these two processes are dominated by Cl− and F−, respectively. A porous surface structure is beneficial to improve the biomineralization activity of Zr-based BMGs.

In this paper, the effect of Mn2+ (≤160 mg/L) on the anodic film properties and corrosion behavior of Pb-0.07%Ca-1.25%Sn anodes in acidic CuSO4 electrolyte is clarified. The anode was polarized in an electrolyte containing different concentrations of Mn2+ ions for 48 h to obtain a stable oxide film on the surface. The phase composition and morphology of the oxide layer formed on the Pb-0.07%Ca-1.25%Sn anode after polarization were characterized by the XRD, SEM, and EDS techniques. The influence of Mn2+ (≤160 mg/L) on the electrochemical behavior of the Pb-0.07%Ca-1.25%Sn anode was investigated in 45 g/L Cu2+ and 180 g/L H2SO4 solution via cyclic voltammetry, galvanostatic polarization, Tafel, and EIS measurements. In addition, the anodic weight loss, film formation, and corrosion mechanism of the anode are also proposed. The results reveal that the film formed on the Pb-0.07%Ca-1.25%Sn anode exhibited a gradient Pb|PbSO4|α-PbO2|α-PbO2-β-MnO2 layer in the Mn2+-containing electrolytes. Then, during the oxygen evolution reaction (OER), the gradient layer was oxidized to MnO2, which was irregularly attached to the surface of the substrate and increased the roughness of the film. The presence of Mn2+ accelerated the corrosion of the anode in the electrolyte and reduced the anodic oxygen evolution potential. When the concentration of Mn2+ ions reached 160 mg/L, the corrosion rate was increased by 62.3% despite the anode potential decreasing by 30 mV.

A new model of the optimum tilt angle of a soiled photovoltaic (PV) panel is proposed in this paper. The tilt angle is a key factor that influences the output power of PV panel, while dust deposition is an inevitable external element to be considered. In this paper, the solar radiation model is studied by analysing the Hay, Davies, Klucher, Reindl (HDKR) model. The cell temperature of a PV panel is also investigated to evaluate the power output. A fitting formula is derived to express the relationship between the dust deposition density and the tilt angle, and it is integrated in the output model of a fixed-type PV panel. Besides, the effect of dust deposition on the transmittance is analysed. An inverse correlation between the dust deposition density and tilt angle can be obtained, and the optimum tilt angle is calculated to maximize the power output of a soiled PV panel. Simulation is conducted by Matlab to demonstrate the validity of the proposed model of the optimum tilt angle with the shielding effect by dust. Furthermore, the relationship between dust deposition and the working temperature of PV panel is investigated by indoor experiments.

Lead dioxide has absorbed much attention for its good resistance to corrosion, high electronic conductivity, good stability, long lifetime, low cost as electrode material. However, there still exist problems about the selection of electrolyte, which may bring trouble in energy conservation and environmental protection. The present study was to provide more environmentally electrolyte of methanesulfonic acid (MSA) and evaluate MSA effect on electrosynthesis of lead dioxide by using rotating disk electrode (RDE) and scanning electron microscope (SEM) as well as X-ray diffraction (XRD) so as to make sure suitable concentration of MSA and to gain more environmental and energy benefit. The results show that methanesulfonic acid has great influence on the electrodeposition of lead dioxide and adequately characterise the PbO2 synthesized on Pt electrode surface. By controlling the composition of the electrodeposition bath at MSA concentration 0.1 M and Pb(II) 0.2 M can we get better reversible process, longer electrode lifetime and more satisfactory environmental protection.

In this paper, a Co3O4- and CNT-doped 3D PbO2 electrode was fabricated through galvanostatic electrodeposition in a Pb(Ac)2-NH2SO3H solution, and the electrochemical properties were systematically investigated in a zinc electrolyte. The XRD results show that the deposit is a mixture of an α + β phase (a dominant β-PbO2 phase with a minor α-PbO2 phase present), and the SEM images show that Co3O4 and CNT have been simultaneously deposited with PbO2. The 3D-Ti/PbO2-(4 g·L−1) Co3O4-(0.4 g·L−1) CNT electrode exhibits a voltammetric charge 5 times larger than that of the 3D-Ti/PbO2 electrode, which indicates outstanding electrocatalytic activity. The oxygen evolution reaction overpotential and cell voltage are only 394 mV and 3.74 V at 500 A∙m−2, respectively. In addition, the obtained electrode showed a high current efficiency of 95.3% and a service life of 26 h under a current density of 20,000 A∙m−2. Hence, this study offers a facial synthesis route to prepare composite electrodes for zinc electrowinning and provides deep insight into the relationship among doping substances, microstructures and electrocatalytic activity.

Chemical looping combustion (CLC) is a novel technology that offers effective CO2 capture and power generation, which strongly relies on the properties of oxygen carrier. Here, a new type of CeO2/MnCo2O4 oxygen carrier was prepared by dispersing CeO2 nanoparticles on MnCo2O4 microspheres for CLC of methane. The results reveal that the pure MnCo2O4 shows high activity for methane combustion (methane conversion is as high as 94% at 800 °C), but the methane conversion sharply decreases to lower than 40% after 20 redox cycles, indicating poor redox stability. The presence of CeO2 on MnCo2O4 microspheres significantly improves the redox stability, which is benefited from the partial incorporation of high valence Ce4+ cations into the MnCo2O4 lattice that results in the generation of abundant oxygen vacancies due to the charge balance. Among different xCeO2/MnCo2O4 samples, the 10% CeO2/MnCo2O4 shows the highest stability during the successive CLC testing either in the capacity for CH4 combustion or in the aspect of structure, which shows a capacity for CH4 combustion at 2.22 mmol/g and the average CH4 conversion higher than 90% on the stable state. Kinetic analysis indicates that the reduction process of recycled 10%CeO2/MnCo2O4 can be divided into two steps (the main reduction of Co and Mn oxides, respectively) based on apparently different reaction rates, and both the two steps can be mainly described by a 1D growth of nuclei model. The activation energy for step 1 and step 2 are 32.34 kJ/mol and 88.54 kJ/mol, respectively.

The behavior of chemical looping reforming of methane over the magnetite oxygen carrier (OC) has been investigated by thermodynamic analysis and experiments, which clarified the appropriate operating conditions and material composition. The possible revolution of the reaction composition and the corresponding isothermal redox reactions also have been carried out. Compared with the effect of temperature rise (800–1000 °C) on the formation of carbon deposition, it is more conducive to the reduction of iron oxide. In the oxidation stage, the temperature of 400–650 °C is favorable for inhibiting the formation of C and Fe3C, which greatly influenced the quality of hydrogen production. The compounds such as FeTiO3, FeTi2O5 and Fe2TiO5 can be regenerated by water vapor. However, FeAl2O4 and MgFe2O4 are irreversible, resulting in the loss of reducible iron species. Equilibrium composition study revealed that syngas with an ideal ratio of (H2/CO = 2) can be obtained at a temperature higher than 900 °C, while the carbon deposition has been inhibited. Both the thermodynamic analysis and experiment showed that the chemical thermodynamics analysis method is a leading approach for the reaction characteristic studies of chemical looping reforming of methane.

It is well known that the structural problem between the autothermal operation and the outside utilization of heat in the catalytic combustion system and the runaway on catalyst bed is hard to avoid during the combustion process. Herein, the encapsulated Co3O4/(SiAl@Al2O3) thermal storage functional catalysts which couple Co3O4 catalysts and SiAl@Al2O3 phase change materials are proposed and firstly applied for catalytic combustion of lean methane to improve the thermal environment of the catalyst bed and achieve the high efficiency of lean methane utilization. The thermal management behaviors of such thermal storage functional catalysts and the dynamic coupling effect between heat storage/release characteristics of catalysts and catalytic performance during methane combustion process are investigated in detail. It is found that the encapsulated Co3O4/(SiAl@Al2O3) thermal storage catalysts retain the high latent heat of SiAl@Al2O3 phase change material (410 J/g) and the values vary from 280 J/g to 30 J/g when the SiAl@Al2O3 content decreases from 90 wt% to 10 wt%. When applying the catalysts to catalytic combustion of lean methane, such thermal storage functional catalysts with high thermal storage density show significant efficiency of lean methane conversion than pure Co3O4, and it can also keep the methane conversion at a high level for a long time even if the external heat source disappears. This indicates that the effective heat management of Co3O4/(SiAl@Al2O3) thermal storage catalysts during methane combustion process plays a crucial role in determining the catalytic activity via improving the thermal runaway and hot spots problems in catalyst bed and reducing heat loss. However, the content of SiAl@Al2O3 needs to be carefully regulated to avoid the decrease of activity resulting from the low active Co3O4 content. Particularly, the Co3O4/(SiAl@Al2O3-30 wt%) catalyst shows a competitive activity (e.g., T10, T50 and T90 at 226, 282 and 370 °C) and it surpasses the activity of pure Co3O4 in literatures although the active Co3O4 content is significantly lower than them. After turning off the heat source for 37 min, its methane conversion can still reach 50%, which is twice that of pure Co3O4. The present approach for thermal management in catalytic methane combustion reaction will provide good references for solving the problems (e.g., temperature runaway and hot-spot) in fixed bed reactors during other complex heterogeneous chemical reactions.

In the present work, nucleation mechanism, preparation conditions, performance testing and application simulation of lead dioxide coating materials prepared by electrodeposition from methanesulfonic acid were studied to improve anodic process in zinc electrowinning process. Phase growth and transformation of lead dioxide were analyzed by anodic polarization curves, X-ray powder diffraction, scanning electron microscopy SEM, electrochemical impedance spectroscopy (EIS) and Tafel curves. The selection of temperature ranges was found to cause a quantitative difference in the formation of α/β-PbO2 phases, as it made interval effects on the overpotential that was the primary control condition to affect transfer process, while without changing the reaction mechanism apparently. In this way, the precise conditions of obtaining α- or β-PbO2 phases by varying temperatures was confirmed and samples were selected to be tested in long-period galvanostatic electrolysis, electrode (deposition time-α&β: 2 h&2 h) showed the best physicochemical properties and could effectively extend the lifetime (70.4 h) compared with the traditional lead dioxide electrodes (32.3 h) in zinc electrowinning.

In this study, a new anode based on Pb-0.3%Ag/α-PbO2/β-PbO2-Co3O4 composite is proposed and its performance is compared with that of the traditional Pb-1wt%Ag anode during long-term zinc electrowinning. The electrocatalytic activity of the new anode for the oxygen evolution reaction (OER) initially decreased and then gradually increased, which was attributed to the phase transition occurring at the surface of the anode, and its corrosion resistance was gradually improved with the progress of electrowinning. Further, the electrochemical characteristics, cell voltage, current efficiency, and energy consumption of the two anodes were evaluated after 16 days of electrowinning. The OER electrocatalytic activity and corrosion resistance of the new anode were observed to be higher than those of the traditional anode. In addition, the cell voltage and power consumption of the new anode were significantly lower than those of the traditional anode. Furthermore, compared to the traditional anode, the energy consumption for producing 1 t of zinc was reduced by 358.13 kWh based on the new anode.

In this study, the oxygen evolution kinetics and oxide layer properties of Pb-0.8%Ag rolled-alloy anodes were investigated during 15 d of galvanostatic electrolysis in an acidic zinc sulfate electrolyte solution containing 600 mg.L-1 Cl-1 ions. Cyclic voltammetry, quasistationary polarization, and electrochemical impedance spectroscopy were used to investigate the anode process. The microscopic morphology and phase composition of the anodic oxide layers were observed by scanning electron microscopy and X-ray diffraction, respectively. The observable variations in the electrocatalytic activity and reaction kinetics of the anodes during electrolysis indicate the formation and stabilization of the anodic oxide layer. With prolonged electrolysis, the oxygen evolution overpotential in the anodes mainly exhibited a decreasing trend, which is contrary to the trend of the electrode surface exchange current density. This depolarization may have been caused by the increasing roughness of the anodic surface and the catalytic effects of alpha-PbO2 and beta-PbO2. As electrolysis continued, the cathodic peak (alpha-PbO2 -> PbSO4) mainly showed an increasing trend and gradually moved toward the negative direction. After 15 days of electrolysis, the oxide layers exhibited a severely corrosive microstructure with plenty of cavities and etch pits. The uniform, well-defined crystal grains and regularity were not appeared. The phase composition of the anodic oxide layer was formed after 6 d of electrolysis. alpha-PbO2 proved to be the main peak and showed preferential growth orientations along the (111) planes of the anodic oxide layer. (C) 2014 Elsevier B.V. All rights reserved.

An Al/conductive coating/α-PbO 2 –CeO 2 –TiO 2 /β-PbO 2 –MnO 2 –WC–ZrO 2 composite electrode material was prepared through electrochemical oxidation co-deposition on an Al/conductive coating/α-PbO 2 –CeO 2 –TiO 2 substrate. The effects of manganese nitrate concentration on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated using energy dispersive X-ray spectroscopy, anode polarization curves, quasi-stationary polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy, and X-ray diffraction. Results revealed that the WC and nano-ZrO 2 content in the β-PbO 2 –MnO 2 –WC–ZrO 2 composite coatings increased with increasing manganese nitrate concentration. Moreover, the highest values of 6.61 wt% and 3.51 wt%, respectively, were achieved at 80 g L −1 manganese nitrate. PbO 2 content decreased and MnO 2 content increased with the increasing manganese nitrate concentration; both the descending and ascending trends were nonlinear. The Al/conductive coating/α-PbO 2 –CeO 2 –TiO 2 /β-PbO 2 –MnO 2 –WC–ZrO 2 composite electrode obtained at 80 g L −1 manganese nitrate concentration in plating solution exhibited reduced overpotential for oxygen evolution (0.610 V at 500 A m −2 ), highest electrocatalytic activity, longest service life (360 h at 40 °C in 150 g L −1 H 2 SO 4 solution at 2 A cm −2 ), and lowest cell voltage (2.75 V at 500 A m −2 ). Furthermore, the composite coating obtained with 80 g L −1 manganese nitrate had uniform crystal grains. The deposit formed was flat, dense, and crackless.

The β-FeOOH nanorods and α-Fe2O3 hollows are successfully fabricated via hydrothermal method. The TEM and XRD analysis indicated that the morphology and size of β-FeOOH nanorods or α-Fe2O3 hollow structure are tuned by multifactorial parameters in preparation process. The water bath temperature, urea concentrations and hydrothermal temperature promotes the diversity on the size of β-FeOOH nanorods, while hydrothermal times beneficial to the different morphologies of β-FeOOH. The calcination treatment helps the phase transformation to α-Fe2O3 and the construction of α-Fe2O3 hollow structure. However, a mature and regular α-Fe2O3 nanohollow must couple the individual roles of above reaction parameters.

In this paper, the oxygen evolution kinetics and oxide layer properties of Pb–0.8%Ag rolled alloy anodes obtained over 15 days of galvanostatic electrolysis in acid zinc sulfate electrolyte solution were investigated using anodic polarization curves, quasi-stationary polarization (Tafel), and electrochemical impedance spectroscopy techniques. The microscopic morphology and phase composition of the anodic oxide layers were observed by scanning electron microscopy and X-ray diffraction, respectively. The activity and reaction kinetics of the anodes varied noticeably during electrolysis, indicating the formation and stabilization of the anodic oxide layer. With increasing electrolysis time, the potential and overpotential of oxygen evolution of the anodes mainly presented a declining trend, whereas their electrode surface exchange current density demonstrated a rising trend. This depolarization can be accounted for by the increasing roughness of the anodic surface and the catalytic effect of increasing β-PbO 2 content. The anodic oxide layer obtained after 15 days of electrolysis presented the most compact and the best regular structure among five experimental samples. The corrosion phases of the anodic oxide layers mainly consisted of PbSO 4 , PbO, α-PbO 2 , and β-PbO 2 . With increasing electrolysis time, the α-PbO 2 content presented a declining trend, whereas the β-PbO 2 content demonstrated a rising trend. α-PbO 2 and β-PbO 2 showed preferential growth orientations toward the (111) and (101) planes, respectively.

In order to search for a suitable anode material in place of Pb–Ag alloy in zinc electrowinning, Al/Pb-PANI(polyaniline)-WC(tungsten carbide) composite inert anodes on aluminum substrates were prepared by double pulse electrodeposition (DPE) of WC and PANI particles with Pb 2+ from an original plating bath, in which solid particles were suspended by mechanical stirring. Thereafter, the anodic polarization curves, cyclic voltammetry curves and tafel polarization curves for the composite inert anodes obtained under different WC concentrations in the original plating bath, were measured in a synthetic zinc electrowinning electrolyte of 50 g·L − 1 Zn 2+ , 150 g·L − 1 H 2 SO 4 and 35 °C, and the microstructural features were also observed by scanning electron microscope (SEM). The results show that the co-deposition of WC and PANI particles with Pb 2+ in the original plating bath, changes the electrocrystallization morphologies for matrix metal Pb on aluminum substrates. Al/Pb-PANI-WC composite inert anode obtained under WC concentration of 30 g·L − 1 and PANI concentration of 20 g·L − 1 in the original plating bath, possesses uniform surface and cross sectional microstructures, higher electrocatalytic activity, lower overpotential of oxygen evolution, better reversibility of electrode reaction, better corrosion resistance and longer service times in a synthetic zinc electrowinning electrolyte of 50 g·L − 1 Zn 2+ , 150 g·L − 1 H 2 SO 4 and 35 °C.

Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth (nano-CeO2) and silicon carbide (nano-SiO2) particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstructures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.

The aim of this research work was to co-deposit nano-SiO2 and nano-CeO2 particles into the Ni–W–P alloy coating in order to improve the surface properties further. Ni–W–P–SiO2–CeO2 composite coatings were prepared by co-deposition of nickel, tungsten, phosphorus, nano-SiO2 and nano-CeO2 particles on the surface of 15 steel from the electroplating bath which nano-SiO2 and nano-CeO2 particles were suspended by high speed mechanical stirring. The characteristics of the composite coatings were assessed by micro hardness test, Taber Abrader test, scanning electron microscopy and X-ray diffraction. The results obtained in this study indicate that the nano-SiO2 and nano-CeO2 particles were dispersed evenly within the Ni–W–P alloy coating and the bonding between the matrix metal and nano-SiO2 and nano-CeO2 particles is compact. That the co-deposition of nickel, tungsten, phosphorus, nano-SiO2 and nano-CeO2 particles leads to uniform Ni–W–P–SiO2–CeO2 composite coatings possessing better micro hardness and abrasion resistance properties when heat-treated at 400 °C for 3 h. In addition, that nano-CeO2 and nano-SiO2 particles can increase the thermal stability of Ni–W–P alloy coating at high temperature.

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE (rare earth)-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r=0.8 is higher than that at r=0.6.

The E–pH diagram for the Co–Sb–H 2 O system indicates that antimony and cobalt combine to form an inter-metallic compound that enhances the thermodynamic driving force of removal of cobalt from zinc electrolyte solution by cementation with zinc powder. The results of scanning electron microscopy and X-ray diffraction show that antimony exists in the same form as nickel and cobalt which suggests that antimony and cobalt combine to form an inter-metallic compound CoSb. However, zinc exists in the form of basic zinc sulphate, zinc oxide and zinc. The activation mechanism of Sb 2 O 3 is investigated in this paper.

The effects of heat treatment temperature and time on the hardness and the wear resistance of RE (rare earth)-Ni-W-P-PTFE-SiC and RE-Ni-W-P-SiC composite coatings have been studied, and the results indicate that the hardness of the composite coatings is lower and the mass loss (i.e., rate of abrasion) is higher in the as-deposited state. The hardness rises and the rate of abrasion decreases with increasing heat treatment temperature; the abrasion rate is lowest and the hardness is highest at 400 °C. The hardness decreases and the rate of abrasion increases with a further rise in the temperature. The hardness and the wear resistance both increase with a rise in heat treatment time, and they reach their peak values after 2 h of heat treatment. The experimental results also show that the hardness of the coating decreases with an increase in PTFE quantity, and the wear rate diminishes correspondingly. X-ray diffraction indicates that the structure of the as-deposited RE-Ni-W-P-PTFE-SiC composite coating is of amorphous status.