Search

Purpose This paper aims to investigate the electrochemical corrosion behavior of a five-layer Al alloy composites (4343/4047/3003/4047/4343) with a thickness of 0.2 mm in NaCl solution. Design/methodology/approach Electrochemical impedance spectroscopy, polarization curve and morphology analyses were used to study the corrosion behavior of the Al alloy composites from cross-sectional and plane directions. Findings The corrosion resistance of the surface from the plane direction was higher than that from the cross sections. Si-enrich particles were observed in the outer 4047/4343 layer, and AlFeCuMnBi phases were identified in the core 3003 layer. The galvanic coupling between the Si-enrich particle and the Al matrix accelerated the dissolution Al matrix. Originality/value This work lays the experimental foundation for corrosion mechanism of the Al alloy composite plate.

We propose a Joule-heating method for the rapid synthesis and OER performance screening of a series of doped oxides for the development of advanced electrocatalysts.

Purpose This paper aims to study the effect of chloride concentration on the properties of passive film formed on Q235 steel in simulated concrete pore solutions. Design/methodology/approach Mott–Schottky analysis and electrochemical impedance spectroscopy were used to study the passive film of Q235 steel in simulated concrete pore solution. X-ray photoelectron spectroscopy was used to analyze the composition of passive film on Q235 steel. Findings When the chloride concentration is below the chloride threshold value, open circuit potential (OCP) and Rct gradually increases and donor concentration (ND) remains unchanged with the increasing immersion time. When the chloride concentration exceeds chloride threshold value, OCP and Rct decreases after a temporary increase and ND increases. The linear region of the Mott–Schottky curve lost its linearity. The electrochemical process control step is changed from charge transfer control to oxygen diffusion control. As the chloride concentration increases, the FeO content in the passive film increases and the Fe2O3 content decreases. Chloride can destroy the outer layer of passive film and introduce impurities. Originality/value The effects of chloride and immersion time on the change process of passive films on Q235 steel in simulated concrete pore solution were studied using electrochemical methods. The mechanism of chloride destroying passive film was analyzed.

High-entropy oxide (HEO) including multiple principal elements possesses great potential for various fields such as basic physics, mechanical properties, energy storage, and catalysis. However, the synthesis method of high-entropy compounds through the traditional heating approach is not conducive to the rapid properties screening, and the current elemental combinations of HEO are also highly limited. Herein, we report a rapid synthesis method for HEO through the Joule-heating of nickel foil with dozens of seconds. High-entropy rocksalt oxides (HERSO) with the new elemental combination, high-entropy spinel oxides (HESO), and high-entropy perovskite oxide (HEPO) have been synthesized through the Joule-heating. The synthesized HERSO with new elemental combinations proves to be a great promotion of OER activity due to the synergy of multiple components and the continuous electronic structure experimentally and theoretically. The demonstrated synthesis approach and the new component combination of HERSO provide a broad platform for the development of high-entropy materials and catalysts.

To enhance the effect of reducing suspension vibration and harvesting the vertical vibration energy of cars, a research was conducted on an energy-regenerative suspension with magnetorheological dampers (MRDs). First, an innovative structure of energy-regenerative dampers was developed, as well as mathematical and simulation models of the damping force and energy harvest. Subsequently, simulation experiments and bench tests were conducted. Based on these, mathematical models of a two-degree-of-freedom semi-active suspension were built, and a whale optimization algorithm- proportional integral derivative (WOA-PID) control algorithm was designed. Simulation experiments were conducted on the working conditions of white-noise and impact road surfaces. The obtained results indicate that the energy-regenerative dampers considered in this study have a certain energy-regenerative capability, and the WOA-PID algorithm exerts an optimal controlling effect on the suspension.

Purpose The purpose of this paper is to clarify the effect of compressive stress on cavitation-erosion corrosion behavior of 304 stainless steel. Design/methodology/approach Compressive stresses of 60 MPa and 120 MPa were applied to 304 stainless steel through a self-designed loading device, and cavitation erosion-corrosion tests were performed using an ultrasonically vibratory apparatus. Scanning electron microscope and X-ray diffraction were used to analyze the microstructure evolution, and corrosion behavior was studied by electrochemical analysis. Findings The cavitation weight loss of 304 stainless steel decreased with the compressive stress. After cavitation corroded for 8 h, the weight loss for the specimen with 120 MPa compressive stress was 5.11 mg/cm2, which was reduced by 56.7% from that of the specimen without loading stress (11.79 mg/cm2). The reason can be attributed to that compressive stress promoted the deformation-induced martensitic transformation during the cavitation process, which could not only provide a cushioning effect by absorbing cavitation impact energy but also improve the hardness of 304 stainless steel. Originality/value Compressive stress was found to restrain the cavitation damage on 304 stainless steel, and the corresponding mechanism was proposed.

Purpose This paper aims to study the effect of Hg2+ on the corrosion behavior of Al–2%Zn coatings on AA5083 in 3.5 Wt.% NaCl solution. Design/methodology/approach Potentiodynamic polarization and electrochemical impedance spectroscopy are used to investigate the effect of Hg2+ on the corrosion behavior. The surface and cross-sectional morphology are characterized by scanning electron microscopy and energy dispersive spectroscopy (EDS) to further reveal the corrosion mechanism of Hg2+. Findings The results show that the corrosion behavior of the coating changes significantly as the concentration of Hg2+ increases from 5 to 30 μg/L. The corrosion production film can inhibit the corrosion process when Hg2+ concentration is in the range of 0.5–5 μg/L, while Hg2+ can promote the corrosion process significantly when its concentration reaches to 30 μg/L. The generation rate of dense oxide film on the coating surface is faster than dissolution rate when the concentration of Hg2+ is in the range of 0–5 μg/L, which makes the coating “self-healing” and thus slightly slows down the corrosion rate. The EDS analysis shows that excessive Hg2+ are preferentially deposited at locations with inhomogeneous electrochemical properties, which in turn accelerates corrosion. Originality/value The corrosion resistance of Al-based coatings is significantly affected by Hg2+ in seawater. Thus, it is important to explain the corrosion mechanism of Al–2%Zn coatings under the combined effect of Hg2+ and Cl− in 3.5 Wt.% NaCl solution.

Because of their high theoretical value of volumetric energy density, excellent rate performance, and high level of safety, zinc-nickel batteries (ZNBs) show potential applications for uninterrupted power supply (UPS) systems. However, despite all the advantages of ZNBs, the commercial application of ZNBs has been prevented by their short lifetime caused by the shape change, the corrosion, and the dendrite formation of the Zn anode. In this work, we proposed a flexible and durable potassium polyacrylate (PAAK)-KOH gel polymer electrolyte (GPE) prepared in a very simple way to solve the above problems of the Zn anode. The obtained highly porous gel electrolyte showed higher water retention, satisfying ionic conductivity (0.918 S cm

Main group metals are routinely considered as catalytically inactive. In this work, we for the first time prepared a p-block tin single atom catalyst (SnSA–NC) with Sn–N4 active site for effectively improving the lithium–sulfur battery performance.

The heat released from an aluminum-air battery has a great effect on its performance and operating life during the discharge process. A theoretical model was proposed to evaluate the resulting thermal effect, and the generated heat was divided into the following sources: anodic aluminum oxidation reaction, cathodic oxygen reduction reaction, heat production against the battery internal resistance, and hydrogen-evolution reaction. Quantitative analysis was conducted on each part, showing that all heat production sources increased with discharge current density. It should be noted that the heat caused by hydrogen evolution accounted for the most, up to 90%. Furthermore, the regulation strategy for inhibiting hydrogen evolution was developed by addition of hybrid additives to the electrolyte, and the hydrogen-evolution rate was greatly reduced by more than 50% as was the generated heat. This research has important guidance for the thermal effect analysis of aluminum–air batteries, together with control of the thermal management process by inhibiting hydrogen evolution, thus promoting their practical application.

In recent years, with the increasing application of lithium-ion batteries in energy storage devices, fire accidents caused by lithium-ion batteries have become more frequent and have arisen wide concern. Due to the safety of aqueous electrolyte, aqueous Zn-based batteries have attracted vast attention, among which Zn-Ni batteries stand out by virtue of their excellent rate performance and environmental friendliness. However, poor cycling life limits the application of Zn-Ni batteries. To figure out the main cause, a failure analysis of a practical Zn-Ni battery has been carried out. During the cycling of the Zn-Ni battery, the evolution of gas, the shape changing, and the aggregation of additive and binder of Zn anode can be observed. Combined with the finite element analysis, we finally reveal that the key factor of battery failure is the shape changing of the Zn anode caused by uneven current distribution and the dissolution of Zn. The shape changing of the Zn anode reduces the effective surface area of anode and increases the possibility of dead Zn, which makes the battery unable to discharge even in the presence of a large amount of Zn. These findings are helpful to deepen the understanding of the working and failure mechanisms of the Zn anode and provide effective guidance for subsequent research.

Purpose Nickel-aluminum bronze (NAB) has been widely used in ship propellers. It is always subjected to local micro-plastic deformation in service environments. This paper aims to study the influence of plastic deformation on the mechanical strength and corrosion resistance of NAB in 3.5 Wt.% NaCl solution. Design/methodology/approach Scanning electron microscope and X-ray diffraction were used to analyze the microstructure of NAB alloy with different plastic deformations. Mechanical properties of the sample were measured by tensile experiment, and corrosion behavior was studied by electrochemical measurements and the long-term immersion corrosion test. Findings Results showed that the plastic deformation caused lattice distortion but did not change the microstructure of NAB alloy. Microhardness and yield strength of NAB were significantly improved with the increase of deformation. The lattice distortion accelerated the formation of corrosion product film, which made the deformed alloy show a more positive open-circuit potential and an increased Rp. However, during the long-term immersion corrosion, the corrosion resistance of NAB alloys deteriorated with the increase of plastic deformation. This is because larger plastic deformation brought about higher internal stress in corrosion product film, which resulted in the premature peeling of the film and the loss of its protective effect on the alloy substrate. Originality/value Tensile plastic deformations were found to cause a decline in the corrosion resistance of NAB. And the mechanism was clarified from the evolution of corrosion products during the corrosion process.

Increasing pursuit of next-generation wearable electronics has put forward the demand of reliable energy devices with high flexibility, durability and enhanced electrochemical performances. Flexible aqueous zinc-air batteries (FAZABs) have attracted great interests owing to the high energy density, safety, and environmental benignity, for which quasi-solid-state gel polymer electrolytes (QSGPEs) are state-of-the-art electrolytes with high ionic conductivity, flexibility and resistance to leakage problems of traditional liquid electrolytes. Compared to commonly used PVA-KOH electrolyte with poor electrolyte retention capability and cycling stability, a new type of sulfonate functionalized nanocomposite QSGPE is applied in FAZABs with high ionic conductivity, strong alkaline tolerance and high zinc anode stability. Notably, the existence of (1) strong anionic sulfonate groups of QSGPEs, contributing to the exposure of preferred Zn (002) plane which is more resistant to zinc dendrite formation, and (2) nano-attapulgite electrolyte additives, beneficial for the enhancement of ionic conductivity, electrolyte uptake and retention capability, endows a ultralong cycling life of 450 h for the fabricated FAZAB. Furthermore, flexible energy belts and knittable energy wires fabricated with a series/parallel unit of several FAZABs could be used to power various wearable electronics. This article is protected by copyright. All rights reserved.

The rapid development of portable, flexible, and wearable devices motivates the requirement for flexible zinc-air batteries (FZABs) not only to provide high energy density but also to have sufficient deformability for wearer comfort. The gel polymer electrolyte (GPE) serves as the core part of the FZABs, playing a key function in the battery's practical output performance such as discharge voltage, energy density, and cycling life. Unfortunately, ascribed to its high water absorption, the GPE regularly shows comparatively poor mechanical strength, which is difficult to offer sufficient physical support between electrodes. Herein, we report an optimized poly(acrylic acid) (PAA)-based composite GPE with the aluminum oxide (Al

Laser processing is employed to fabricated zinc-ion battery (ZIB) anodes with state-of-the-art electrochemical performance from commercial zinc foils. Lasers are widely utilized for industrial surface finishing but have received minimal attention for zinc surface modification. Laser lithography patterned zinc foils “LLP@ZF” are hydrophilic, with an electrolyte contact angle of 0°. This is due to the concave-convex surface geometry that enhances wetting (periodic crests, ridges and valleys, roughness 16.5 times planar). During electrodeposition LLP@ZF's surface geometry generates a periodic electric field and associated current density distribution that suppresses tip growth (per continuum simulations). Per Density Functional Theory (DFT) its surface oxide is zincophilic, resulting in low nucleation barriers during plating (e.g. 3.8 mV at 1 mA cm−2). A combination of these attributes leads to stable dendrite-free plating/stripping behavior and low overpotentials at fast charge (e.g. 48.2 mV at 8 mA cm−2 in symmetric cell). Cycling is possible at an unprecedented areal capacity of 50 mA h cm−2, with 400 h stability at 1 mA cm−2. Moreover, exceptional aqueous zinc battery (AZB) performance is achieved, with MnO2-based cathode loading 10 mg cm−2 and corresponding anode capacity 7.6 mA h cm−2. A broad comparison with literature indicates that LLP@ZF symmetric cell and full battery performance are among most favorable.\ud \ud

Potassium–sulfur batteries (KSBs) are regarded as a promising large-scale energy storage technology, owing to the high theoretical specific capacity and intrinsically low cost. However, the commercialization of KSBs is hampered by the low sulfur utilization and notorious shuttle effect. Herein, we employ a porosity engineering strategy to design nitrogen-rich carbon foam as an efficient sulfur host. The tremendous micropores magnify the chemical interaction between sulfur species and the polar nitrogen functionalities decorated carbon surface, which significantly improve the sulfur utilization and conversion. Meanwhile, the abundant mesopores provide ample spaces, accommodating the large volume changes of sulfur upon reversible potassation. Resultantly, the constructed sulfur cathode delivers an ultrahigh initial reversible capacity of 1470 mAh g−1 (87.76% of theoretical capacity) and a superior rate capacity of 560 mAh g−1 at 2 C. Reaching the K2S phase in potassiation is the essential reason for obtaining the ultrahigh capacity. Nonetheless, systematic kinetics analyses demonstrate that the K2S involved depotassiation deteriorates the charge kinetics. The density functional theory (DFT) calculation revealed that the nitrogen-rich micropore surface facilitated the sulfur reduction for K2S but created a higher energy barrier for the K2S decomposition, which explained the discrepancy in kinetics modification effect produced by the porosity engineering.

It remains challenging to develop economical and bifunctional electrocatalysts toward oxygen/hydrogen evolution reactions (OER/HER). Herein, we construct Co9S8 nanoflakes decorated Co3O4 nanoarrays with enriched heterogeneous interface zones on Ni foam (Co9S8@Co3O4/NF) via a novel step-wise approach. The Co9S8@Co3O4/NF hybrid manifests excellent performance with low overpotentials of 130 mV for HER (10 mA·cm−2) and 331 mV for OER (100 mA·cm−2), delivering a small voltage of 1.52 V for water splitting at 10 mA·cm−2 as well as outstanding catalytic durability, which surpasses precious metals and previously reported earth-abundant nanocatalysts. Further experimental and theoretical investigations demonstrate that the excellent performance is attributed to the followings: (i) Highly conductive Ni facilitates the efficient charge transfer; (ii) porous core-shell nanoarchitecture benefits the infiltration and transportation of gases/ions; (iii) heterogeneous interface zones synergistically lower the chemisorption energy of hydrogen/oxygen intermediates. This work will shed light on the controllable synthesis and engineering of heterostructure nanomaterials for clean energy storage and conversion technologies.

The development of efficient strategies to recycle lithium-ion battery (LIB) electrode materials is an important yet challenging goal for the sustainable management of battery waste. This work reports a facile and economically efficient method to convert spent cathode material, LiFePO4, into a high-performance NiFe oxy/hydroxide catalyst for the oxygen evolution reaction (OER). Herein, Ni-LiFePO4 is synthesized via the wetness impregnation method and further evolves into defect-rich NiFe oxy/hydroxide nanosheets during the OER. The introduction of the Ni promoter together with in situ evolution strengthens the electronic interactions among the metal sites and creates an abundance of defects. Experimentally, the evolved Ni-LiFePO4 delivers a low overpotential of 285 mV at 10 mA cm−2 and a small Tafel slope of 45 mV dec−1, outperforming pristine LiFePO4 and is even superior to the benchmark catalyst RuO2. Density functional theory (DFT) calculations reveal that the introduction of Ni effectively activates Fe sites by optimizing the free energy of the *OOH intermediate and that the abundance of oxygen defects facilitates the oxygen desorption step, synergistically enhancing the OER performance of LiFePO4. As a green and versatile method, this is a new opportunity for the scalable fabrication of excellent electrocatalysts based on spent cathode materials.

Exploring active materials with a high rate capability and long lifespan for sodium ion batteries attracts much more attention and plays an important role in realizing clean energy storage and conversion. The strategy of optimizing the electronic structure by atomic element substitution within MoS2 layers was employed to change the inherent physical property. The enhanced electronic conductivity from a decreased bandgap and increased surface Na+ adsorption energy can efficiently and dramatically optimize the electrochemical performance for sodium storage. Attempting to limit the large volume variation and avoid MoS2 nanosheet stacking and restacking, numerous nanosheets are in situ grown into a designed hierarchical mesopore carbon matrix. This structure can tightly capture the nanosheets to prevent them from aggregating and offer a sufficient buffer zone for alleviating severe volume changes during the discharging/charging process, contributing remarkably to the structural integrity and superior rate performance of electrodes.

As one of the most promising energy storage systems, conventional lithium-ion batteries based on the organic electrolyte have posed challenges to the safety, fabrication, and environmental friendliness. By virtue of the high safety and ionic conductivity of water, aqueous lithium-ion battery (ALIB) has emerged as a potential alternative. Whereas, the narrow electrochemical stability window (ESW) of water severely restricts the performance of ALIB. In recent years, with the introduction of water-in-salt electrolyte (21 mol LiTFSI in 1 kg H2O), the ESW of aqueous electrolyte was expanded to ~3 V, which significantly improved the voltage and energy density of ALIBs. Nevertheless, in view of such high salt concentration, water-in-salt electrolyte will dramatically increase the cost of ALIBs. Hence, due to their lower cost and abundant resource, aqueous sodium-ion batteries and zinc-based batteries show great potential. Herein, the latest advances of water-in-salt electrolyte in aqueous rechargeable batteries are briefly reviewed. Some challenges and prospects of water-in-salt electrolyte are also discussed to broaden the horizons for future development.

The demand for large energy storage systems is consecutively increasing, which requires low-cost and renewable batteries technologies with sustainable performance. Potassium, as the nearest element to sodium and lithium in the IA group of the periodic table, possesses excellent superiorities in electrochemical energy storage devices. Correspondingly, numerous electrode materials with excellent stability and capability have been developed for rechargeable potassium-ion batteries (KIBs). In this review, recent results of electrode materials concerning different types of electrolytes (organic electrolyte, aqueous electrolyte, and all-solid-state electrolyte) for rechargeable KIBs are summarized. An overall content of ongoing cathode/anode electrode materials utilized in rechargeable KIBs with organic electrolyte is reviewed. The topic focuses on employing organic compounds, Prussian blue analogues, layered oxides, and polyanionic compounds as cathode. In addition, different anode materials such as intercalation compounds, alloy compounds, conversion compounds, and organic compounds were discussed. Furthermore, the current research progress of other potassium-based electrochemical energy storage devices (KEES) with low costs and high specific energy densities, such as potassium-ion hybrid capacitors (KIHCs) and potassium dual-ion batteries (KDIBs), are also summarized. Finally, we pointed out the current challenges and future directions of KEES.

The rational design and controllable synthesis of excellent bifunctional oxygen reduction and evolution reaction (ORR/OER) electrocatalysts are of vital importance for zinc–air battery applications. Herein, we report nitrogen/sulfur-codoped carbon nanosheets (NSC) decorated with dense Co9S8/Co1−xS heterostructures (Co9S8/Co1−xS@NSC), prepared by a one-pot salt template-assisted pyrolysis procedure. The population of the Co9S8/Co1−xS heterostructure can be effectively controlled by tuning the precursor components. Salt templates constructed hierarchical porosity for the wide-open carbon nanosheets, which maximized the N functional groups to anchor highly dispersive Co9S8/Co1−xS species. Experiments and theoretical simulations revealed notable electronic interactions within Co9S8/Co1−xS interfaces, which can effectively optimize the adsorption/desorption behaviors of intermediates in ORR/OER, thus promoting the bifunctional electrocatalytic performance. The half-wave potential for the ORR of 0.86 V and the OER electrocatalytic potential of 1.52 V at 10 mA cm−2 were obtained. Benefiting from the strong coupling effect between the Co9S8/Co1−xS species and the carbon substrate, superior durability was obtained for 2000 ORR/OER cycles. The practical zinc–air battery based on the Co9S8/Co1−xS@NSC cathode manifested a high open-circuit voltage, small voltage gap and robust reversibility. Our study revealed the great potential of the bi-elemental (Co and S) heterostructure in enhancing the ORR/OER activity, which suggests a logical extension to other electrocatalysis systems.

Long-time thermal batteries with high specific energy are crucial for improving the fast response ability of long-range weapons. Due to its high capacity, safety, and stability, the new sulfide cathode has attracted extensive attention. In this study, an FeS2@CoS2 composite cathode with a core–shell structure was prepared via a combination of hydrothermal and high-temperature vulcanization processes. The novel FeS2@CoS2 cathode not only delivers a high discharge voltage and output capacity, but also has high thermal stability and excellent conductivity. Benefiting from the synergistic effect of FeS2 and CoS2, the as-synthesized cathode yields a high specific capacity. At a large current density of 1 A/cm2, the utilization rate of FeS2@CoS2 cathode material can reach 72.33%, which is 8.23% higher than that of FeS2. Moreover, the maximum output capacity is up to 902 As/g, with a utilization rate of 79.02% at 500 mA/cm2. This novel design strategy holds great promise for the development and application of high-performance thermal batteries in the future.

After decades of development, zinc-based batteries with the advantages of high energy density, low cost, and environmental benignity have been considered as a promising battery system in the application of energy storage. However, the poor cycle performance of zinc anode strongly restricts the cycle life of zinc-based batteries and thus limits its large-scale application. Electrolyte additives have been proven to be one of the most straightforward strategies in improving the stability of zinc anode during cycles, while the options of additives are still limited. This work is based on the in-depth investigation of the electrochemical behavior of both the organic additives and the zinc species in the electrolyte. The modification effects of poly(vinyl alcohol) (PVA) and vanillin as two typical additives from the electroplating industry in both the zinc plating and zinc anode are systematically studied. It is revealed that PVA could increase the utilization and rate performance of the anode, while greatly promoting the corrosion and shape change of the zinc anode. On the contrary, the existence of vanillin could maintain the structure of the anode during cycles, while the rate performance of the battery is hindered. With the coaddition of the PVA and vanillin, the zinc anode shows superior performance in cycle life, rate performance, active material utilization, and discharge energy retention. These findings provide insight for the enrichment of electrolyte additives in zinc-based batteries.

This paper proposes a novel particle image velocimetry (PIV) technique to generate an instantaneous two-dimensional velocity field for sediment-laden fluid based on the optical flow algorithm of ultrasound imaging. In this paper, an ultrasonic PIV (UIV) system is constructed by integrating a medical ultrasound instrument and an ultrasonic particle image velocimetry algorithm. The medical ultrasound instrument with a phased sensor array is used to acquire acoustic echo signals of particles in water and generate two-dimensional underwater ultrasound images. Based on the optical flow field, the instantaneous velocity of the particles in water corresponding to the pixels in the ultrasonic particle images is derived from the grayscale change between adjacent images under the L-K local constraint based on the optical flow field, and finally, the two-dimensional flow field is obtained. Through multiple sets of experiments, the proposed algorithm is verified. The experimental results are compared with those of the conventional cross-correlation algorithms. The results show that the L-K optical flow method can not only obtain the underwater velocity field accurately, but also has the advantages of good smoothness and extensive suitability, especially for the flow field measurement in sediment-laden fluid than conventional algorithms.

The development of efficient and low-cost flexible metal electrodes is significant for flexible rechargeable zinc-air batteries (ZABs). Herein, we reported a new type of flexible metal (zinc and nickel) electrode fabricated

Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction (OER) and the impairment of chlorine electrochemistry at anode. Herein, we report a heterostructure of Ni3S2 nanoarray with secondary Fe-Ni(OH)2 lamellar edges that exposes abundant active sites towards seawater oxidation. The resultant Fe-Ni(OH)2/Ni3S2 nanoarray works directly as a free-standing anodic electrode in alkaline artificial seawater. It only requires an overpotential of 269 mV to afford a current density of 10 mA·cm−2 and the Tafel slope is as low as 46 mV·dec−1. The 27-hour chronopotentiometry operated at high current density of 100 mA·cm−2 shows negligible deterioration, suggesting good stability of the Fe·Ni(OH)2/Ni3S2@NF electrode. Faraday efficiency for oxygen evolution is up to ∼ 95%, revealing decent selectivity of the catalyst in saline water. Such desirable catalytic performance could be benefitted from the introduction of Fe activator and the heterostructure that offers massive active and selective sites. The density functional theory (DFT) calculations indicate that the OER has lower theoretical overpotential than Cl2 evolution reaction in Fe sites, which is contrary to that of Ni sites. The experimental and theoretical study provides a strong support for the rational design of high-performance Fe-based electrodes for industrial seawater electrolysis.

The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications, including their potential usage as high-efficiency nanoarchitectures for supercapacitors (SCs) as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices. Here, we reported a facile and controllable synthesis of core-shell NiS/Ni3S2@NiWO4 nanoarrays to fabricate a freestanding electrode for hybrid SCs. Impressively, the as-prepared freestanding NiS/Ni3S2@NiWO4 electrode presents an ultrahigh areal capacity of 2032 μA h cm−2 at 5 mA cm−2, and a capacity retention of 63.6% even when the current density increased up to 50 mA cm−2. Remarkably, the NiS/Ni3S2@NiWO4 nanoarray-based hybrid SC delivers a maximum energy density of 1.283 mW h cm−2 at 3.128 mW cm−2 and a maximum power density of 41.105 mW cm−2 at 0.753 mW h cm−2. Furthermore, the hybrid SC exhibits a capacity retention of 89.6% even after continuous 10,000 cycles, proving its superior stability. This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.

The rapid consumption of fossil fuels has caused increasingly climatic issues and energy crisis, which leads to the urgent demand for developing sustainable and clean energies. Electrocatalysts play a key role in the development of electrochemical energy conversion and storage devices. Especially, developing efficient and cost-effective catalysts is important for the large-scale application of these devices. Among various electrocatalyst candidates, earth abundant transition metal compound (TMC)-based electrocatalysts are being widely and rapidly studied owing to their high electrocatalytic performances. This paper reviews the recent and representative advances in efficient TMC-based electrocatalysts (i.e., oxides, sulfides, selenides, phosphides, carbides and nitrides) for energy electrocatalytic reactions, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Different compounds with different applications are summarized and the relative mechanisms are also discussed. The strategies for developing earth-abundant and low-cost TMC-based electrocatalysts are introduced. In the end, the current challenges and future perspectives in the development of TMC research are briefly discussed. This review also provides the latest advance and outlines the frontiers in TMC-based electrocatalysts, which should provide inspirations for the further development of low-cost and high-efficiency catalysts for sustainable clean energy technologies.

Purpose This paper aims to study the effect of flow rate (0.42∼2.09 m/s) on the corrosion behavior of WB36CN1 steel pipe in the simulated secondary circuit water environment (170°C, 6 mg/L ethanolamine + 100 µg/L NaCl), for which an autoclave was used to simulate the secondary circuit environment for carrying out related experiments. Design/methodology/approach The corrosion behaviors were studied by electrochemical methods, morphological observations and elemental analysis. Findings As flow rate increases, the amplitude of the current noise fluctuates increased, noise resistance Rn and spectral noise resistance Rsn decreased, the shear stress on the surface of WB36CN1 steel increases, the oxygen content on the surface decreases, the roughness becomes smaller. Meanwhile, the energy of energy distribution plot is concentrated at high frequencies under the three flow conditions, the slopes of current power spectral density curve approach 0 db/decade. This means that the oxide on the surface becomes less and corrosion rate increases with increasing flow rate. The corrosion type of WB36CN1 steel was uniform corrosion; the degree of uniform corrosion is higher at high flow rate. Originality/value The effect of flow rate on the corrosion behavior of WB36CN1 steel pipe in the secondary circuit water environment was studied by using electrochemical methods in the laboratory. The effect mechanism of flow rate for corrosion behavior was obtained.

The Pt-based catalyst tends to be poisoned by carbon monoxide (CO)-like intermediates produced in fuel cell reactions, which seriously deteriorates its catalytic performance. Herein, noble metal Au with the capacity of resistance to CO-like intermediates poisoning was employed to construct multi-element Pt-based catalysts. Two trimetallic NiPtAu hollow nanocrystals (HNCs) with different surface Au contents were synthesized to explore the role of Au in electrocatalysis for alkaline methanol oxidation reaction (MOR). The trimetallic NiPtAu-SRAu HNCs catalyst with the relative rich Au content (15.17 at%) on surface exhibits a much lower CO oxidation peak potential than the other HNCs counterpart and 20 wt% Pt/C, which indicates the more exceptional CO-resisting performance. Besides, the MOR specific activity of NiPtAu-SRAu HNCs (31.52 mA cm−2) is 7 times higher than that of 20wt% Pt/C (4.50 mA cm−2). This enhancement in catalytic activity as well as anti-CO poisoning capability for NiPtAu-SRAu HNCs can be mainly ascribed to the weakened CO adsorption due to the exposure of Au atoms on NiPt surface evidenced by the experimental data and density functional theory calculations. This study not only investigates the role of Au in MOR catalysis but also could be helpful for designing and optimizing the electrocatalysts for high-active and robust fuel cell applications.

Ion exchange membranes (IEMs) play important roles in energy generation and storage field, such as fuel cell, flow battery, however, a major barrier in the way of large-scale application is the high cost of membranes (e.g., Nafion membranes price generally exceeds USD$ 200 m