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We have developed an efficient strategy to synthesize an active and durable electrocatalyst of Pd hydride nanocubes (NCs). Instead of the traditional chemical method, the PdH0.43 NCs are firstly prepared via a hydrogen diffusion procedure, followed by hydrothermal synthesis of an amorphous CuO layer encapsulating the PdH0.43 NCs to prevent the hydrogen atoms from escaping. Obvious lattice expansion is demonstrated playing a pivotal role in the enhancement of their oxygen reduction reaction (ORR) activity and durability. The obtained PdH0.43@CuO NCs catalysts exhibit an ORR mass activity of 0.18 A mg−1 at 0.90 V versus reversible hydrogen electrode in an alkaline medium, which is about five times higher than that of commercial Pt/C. Accelerated durability tests show that there is only a 32 mV decay in half-wave potential even after 10,000 potential cycles, indicating the excellent stability of PdH0.43@CuO NCs. Density functional theory (DFT) calculations also indicate that, compared to Pd, PdH0.43 has a lower limiting barrier to form OH− during the ORR process. The present study illustrates the importance of lattice expansion caused by hydrogen and offers an available strategy to design highly efficient and durable Pd-based electrocatalysts for alkaline fuel cells.

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.

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.

Oxygen evolution and oxygen reduction are considered as essential processes in the energy conversion devices. The progress of cost-effective bifunctional catalysts has become a critical issue to be solved. Here, we report that Co(OH)2 @N-doped carbon (NC) was facilely synthesized through the impregnation strategy of metal-organic frameworks derived carbon and cobalt ions. N-doped carbon with porous structure and cobalt hydroxide nanosheets play a synergistic effect role, representing excellent catalytic performance toward oxygen evolution and reduction reactions. The obtained Co(OH)2@NC exhibits remarkable activity in terms of a lower overpotential of 330 mV@10 mA cm−2 for OER and a more positive half-wave potential (E1/2 = 0.84 V) for ORR in alkaline medium, outperforming IrO2 and Pt/C. Due to its superior bifunctional catalytic performance, Co(OH)2@NC catalyst is applied into a promising air electrode of Zn-air battery. This presented strategy of impregnation synthesis in this work provides a new design direction for practical electrochemical energy devices.

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.

The rapidly increasing demand for clean and efficient energy devices is a critical issue for the sustainable development of human society. The green and low-cost aqueous zinc–air batteries (ZABs) w...

Tuning the electronic states near the Fermi level can effectively facilitate the reaction kinetics. However, elucidating the role of a specific electronic state of metal oxide in simultaneously regulating the CO 2 electroreduction reaction (CO 2 RR) and competing hydrogen evolution reaction (HER) is still rare, making it difficult to accurately predict the practical CO 2 RR performance. Herein, replacing the Zn site by heteroatoms with different outer electrons (Mo and Cu) is found to tune both occupied and unoccupied orbitals near the Fermi level of ZnO. Moreover, the different electronic states significantly modulate both CO 2 RR and HER activity with a totally inverse trend, thus dramatically tuning the practical CO 2 RR performance. In parallel, the correlation between electronic states, reaction free energies and practical activity is demonstrated. This work provides a possibility for engineering efficient CO 2 RR eletrocatalysts through tunable composition and electronic structures.

In view of increasing drug resistance, ecofriendly photoelectrical materials are promising alternatives to antibiotics. Here we design an interfacial Schottky junction of Bi2S3/Ti3C2Tx resulting from the contact potential difference between Ti3C2Tx and Bi2S3. The different work functions induce the formation of a local electrophilic/nucleophilic region. The self-driven charge transfer across the interface increases the local electron density on Ti3C2Tx. The formed Schottky barrier inhibits the backflow of electrons and boosts the charge transfer and separation. The photocatalytic activity of Bi2S3/Ti3C2Tx intensively improved the amount of reactive oxygen species under 808 nm near-infrared radiation. They kill 99.86% of Staphylococcus aureus and 99.92% of Escherichia coli with the assistance of hyperthermia within 10 min. We propose the theory of interfacial engineering based on work function and accordingly design the ecofriendly photoresponsive Schottky junction using two kinds of components with different work functions to effectively eradicate bacterial infection.

Developing high activity and low-cost materials to produce hydrogen by the sustainable way of photoelectrochemical is key to social development. The abundance and inexpensive Cu2O has been received increasing research as its suitable energy level for photocatalytic water reduction. However, the fast charge recombination rate and the sluggish catalytic kinetics are the huge challenges facing the Cu2O photoreduction. Here, the highly reactive Cu2O@C-MoS2 photocathode is constructed by depositing dual-cocatalysts of the carbon layer and MoS2 nanosheets on Cu2O nanowires to realize efficient water reduction. An impressive carrier concentration of 6.59 × 1023 cm−3 is received, which is 2.78 times of the bare Cu2O, resulting in remarkable enhancement in photocurrent density of 3.34 times for the Cu2O@C-MoS2 photocathode. Moreover, the applied bias photon-to-current conversion efficiency of the bare Cu2O enhanced 4.5 times from 0.16 % to 0.72 % in the Cu2O@C-MoS2 photocathode. The analysis shows that the Cu2O as light absorber, the carbon layer as electron transfer promoter, and MoS2 nanosheets as catalytic sites, thus facilitating chrage separation and enhancing catalytic kinetics. This system paves a feasible strategy for designing other photoelectrodes to realize efficient charge separation and high catalytic activity.

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.

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.

Material degradation is accompanied by the changes in surface structure, morphology, and composition. These changes can be recorded by a variety of image acquisition devices that export digital images in grayscale or true color to a detector. Information regarding corrosion type and extent can be extracted with image processing methods. This paper provides a comprehensive review of material degradation assessed by digital image processing. Digital image processing systems used to assess material degradation are briefly reviewed, and the algorithms developed to process metallic materials degradation images are described. Physical and electrochemical methods that can be used to support digital image processing results are summarized, and future work that will augment the present methods of evaluating material degradation are discussed.

The Al2O3 powder was added as a filler to polyurea and the effect of doping amount on Shore hardness and wetting property were investigated. The electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion resistance of coating/aluminum alloy system in 0.1 mol/L NaOH solution. The results showed that with the increase of the doping amount, the Shore hardness of the coating increased and the contact angle on the aluminum alloy matrix decreased. By analyzing the results of the characteristics of EIS and the fitting results, doped Al2O3 powder can improve the coating corrosion resistance, but it may affect the density of the coating and reduce the impedance modulus during the initial stage of immersion. The relationship between the doping amount of Al2O3 powder and the corrosion resistance in this test was 5 wt % > 10 wt % > 15 wt % > 0 wt %. In general, in the doping range of this test, since the powder was uniformly distributed in the polyurea coating, the cohesive force of the polyurea can be lowered to cause an increase in the wetting property. At the same time, excessive dopped Al2O3 powder may deteriorate the compactness of the polyurea and the binding property of the polyurea itself may decrease, resulting in deterioration of corrosion resistance. However, the proper doping of Al2O3 powder in polyurea improves its overall performance.

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.

Cu2 O is a typical photoelectrocatalyst for sustainable hydrogen production, while the fast charge recombination hinders its further development. Herein, Ni2+ cations have been doped into a Cu2 O lattice (named as Ni-Cu2 O) by a simple hydrothermal method and act as electron traps. Theoretical results predict that the Ni dopants produce an acceptor impurity level and lower the energy barrier of hydrogen evolution. Photoelectrochemical (PEC) measurements demonstrate that Ni-Cu2 O exhibits a photocurrent density of 0.83 mA cm-2 , which is 1.34 times higher than that of Cu2 O. And the photostability has been enhanced by 7.81 times. Moreover, characterizations confirm the enhanced light-harvesting, facilitated charge separation and transfer, prolonged charge lifetime, and increased carrier concentration of Ni-Cu2 O. This work provides deep insight into how acceptor-doping modifies the electronic structure and optimizes the PEC process.

The microporous nanocrystalline chromium coatings were prepared on the H13 steel by electroplating in self-regulating baths. The effects of electroplating parameters including current density, compositions of baths, bath temperature and plating time on the surface quality, thickness of chromium coating and cathode current efficiency were investigated by an orthogonal experiment. Experimental results indicated that the surface quality, thickness of chromium coating and cathode current efficiency can be improved by adjusting these electroplating parameters. Furthermore, bath temperature has the greatest effect on the surface quality of chromium coating, and the high qualified surfaces were only obtained at higher temperatures of 55 and 65°C. Current density was the most significant factor for the thickness of coating and cathode current efficiency. Chromium coating with high surface quality, thickness and cathode current efficiency was obtained at current density 90 A/dm2, CrO3 250 g/L, K2SiF6 10 g/L, SrSO4 1 g/L, bath temperature 65°C and plating time 120 min, which is consisting of pure nanocrystalline chromium with a body-centered cubic structure. And the coating exhibits much higher microhardness and corrosion resistance than for H13 steel.

We propose and demonstrate Mach-Zehnder interferometer (MZI), which is the refractive index (RI) insensitive and temperature highly sensitive based on etched multi-core fiber (MCF) structure. The MCF and Fiber Bragg Grating (FBG) are used as hybrid sensing elements. The fabrication of the interferometer is provided a new taper-like structure by etching the MCF to further expose the side cores to the surroundings. The interferometer has produced a sensitivity of 103.2pm/°C within the ambient temperature up-to 70°C. Moreover, the superior temperature sensitivity is 89.19pm/°C, 66.64pm/°C, 56.42pm/°C in the range of 24°C to 130°C, and RI-insensitive in the range of 1.34 to 1.38, for different waists of etched seven-core fiber interferometers (E7CFIs) $\sim ~84.70\mu \text{m}$ , $93.10\mu \text{m}$ , $108.67\mu \text{m}$ , respectively. Compared with the conventional FBGs, the sensitivity of the interferometer is significantly improved by 8 times. E7CFI’s novel and advantageous features can easily be distinguished other devices. Besides, the proposed sensing architecture is compact, easy to fabricate, highly sensitive, easy to reproduce, and makes it an inexpensive fiber optic device.

Energy and environmental issues received widespread attentions due to the fast growth of world population and rapid development of social economy. As a transition metal dichalcogenide, tungsten disulfide (WS2) nanomaterials make important research progress in the field of energy conversion and storage. In view of the versatile and rich microstructure of these materials, the modification and controllable synthesis of WS2 nanomaterials also inspire a research interest. This review mainly focuses on WS2-based nanomaterials in the application of energy conversion and storage as well as discusses some basic characteristics and modification strategies of them. Finally, the research progress of WS2-based nanomaterials is reviewed and some prospects for future research directions are proposed. This review is expected to be beneficial to the future study of WS2 nanomaterials used in the field of energy conversion and storage.

Aqueous battery systems feature high safety, but they usually suffer from low voltage and low energy density, restricting their applications in large-scale storage. Here, we propose an electrolyte-decoupling strategy to maximize the full potential of Zn–MnO2 batteries by simultaneously enabling the optimal redox chemistry of both the Zn and MnO2 electrodes. The decoupled Zn–MnO2 battery exhibits an open-circuit voltage of 2.83 V (in contrast to the typical voltage of 1.5 V in conventional Zn–MnO2 batteries), as well as cyclability with only 2% capacity fading after deep cycling for 200 h. Benefiting from the full utilization of MnO2, the Zn–MnO2 battery is also able to maintain approximately 100% of its capacity at various discharge current densities. We also demonstrate the feasibility of integrating the Zn–MnO2 battery with a wind and photovoltaic hybrid power generating system. This electrolyte-decoupling strategy is shown to be applicable for other high-performance zinc-based aqueous batteries such as Zn–Cu and Zn–Ag batteries. Low energy density and limited cyclability are preventing the commercialization of aqueous Zn–MnO2 batteries. Here, the authors combine the merits of operating Zn anodes in alkaline conditions and MnO2 cathodes in acidic conditions, via an electrolyte-decoupling strategy, to realize high-performance batteries.

Stainless steel (SS) is one of the most widely used engineering materials in marine engineering. However, its corrosion in the marine atmospheric environment due to the high concentration of Cl− is a problem. The SS corrosion is a threat to the development and security of marine industry; therefore, evaluating the corrosion resistance of SSs is necessary. In this work, atmospheric corrosion detection probes based on a symmetrical electrode system were used to study the corrosion behaviors of 304 SS and 2205 duplex stainless steel (DSS) in a simulated marine atmosphere. A theoretical model for electrochemical noise (EN) data analysis based on the Thevenin electrochemical equivalent circuit (EEC) model was established. The relationship between the EN characteristic parameters and the corrosion rate was obtained. The Thevenin EEC model analysis showed that the relationship between the noise resistance (Rn), the noise impedance [Rsn(f)], and the impedance modulus (|Z(f)|) was $$R_{{\text{n}}} \approx R_{{{\text{sn}}}} = {}^{\sqrt 3 }\left| {Z(f)} \right|$$Rn≈Rsn=3Z(f). Thus, Rn and Rsn can be used as indicators for quantitative corrosion evaluation. The results of EN detection for the 304 SS and 2205 DSS showed that in a simulated marine atmospheric environment, the passive films on the two SSs were relatively intact at the initial exposure stage, and their dissolution rates were slow. The corrosion resistance of the 2205 DSS was higher than that of the 304 SS. With the deposition of Cl− on the SS surface, pitting was initiated and the dissolution rate increased. The pitting initiation process on the SS surface was random, and part of the active pores could be repassivated.

A fiber-optic shape sensing based on 7-core fiber Bragg gratings (FBGs) is proposed and experimentally demonstrated. The investigations are presented for two-dimensional and three-dimensional shape reconstruction by distinguishing bending and twisting of 7-core optical fiber with FBGs. The curvature and bending orientation can be calculated by acquiring FBG wavelengths from any two side cores among the six outer cores. And the shape sensing in three-dimensional (3D) space is computed by analytic geometry theory. The experiments corresponding of two-dimensional (2D) and 3D shape sensing are demonstrated and conducted to verify the theoretical principles. The resolution of curvature is about 0.1m−1 for 2D measuring. The error of angle in shape reconstruction is about 1.89° for 3D measuring. The proposed sensing technique based on 7-core FBGs is promising of high feasibility, stability, and repeatability, especially for the distinguishing ability on the bending orientation due to the six symmetrical cores on the cross-section.

The purpose of this work was to enhance the corrosion resistance of the passive film on 304 stainless steel (SS) by chemical modification in alkaline phosphate–molybdate solutions. The 304 SS was passivated in both phosphate and phosphate–molybdate mixed solutions to investigate the effect of molybdate on its corrosion resistance. The experimental results indicated that the passive film showed better corrosion resistance in Cl−-containing solutions after modification in phosphate–molybdate solutions than in phosphate-only solutions. Energy-dispersive spectroscopy analyses revealed that the passive film formed in phosphate–molybdate solutions contained Mo and P after modification, which is the reason for the enhanced corrosion resistance.

Developing superior electrocatalysts for formic acid oxidation (FAO) is the most crucial step in commercializing direct formic acid fuel cells. Herein, we electrodeposited palladium membranes with periodically ordered mesoporosity obtained by asymmetrically replicating the bicontinuous cubic phase structure of a lyotropic liquid-crystal template. The Pd membrane with the largest periodicity and highest degree of order delivered up to 90.5 m2 g-1 of electrochemical active surface area and 3.34 A mg-1 electrocatalysis capability towards FAO, 3.8 and 7.8 times the values of the commercial Pd/C catalyst, respectively. By controlling the temperature and potential of the electrodeposition procedure, the periodicity area and order degree of the mesoporosity are highly tunable. These Pd membranes gave prototype formic acid fueled cells with 4.3 and 2.4 times the maximum current and power density of the commercial Pd/C catalyst.

Developing inexpensive and high efficient catalysts is essential for generating oxygen and hydrogen via water splitting. Herein, based on powder metallurgy, a Ni-Fe based compound (Ni8Fe2 alloy) with unique porous structure and controllable phase has been designed and synthesized. Without using a solvent or template, the alloy exhibits a porous structure with uniformly distributed multi-phase. The obtained Ni8Fe2 alloy exhibits an efficient oxygen evolution reaction (OER) performance and good long-term stability in alkaline electrolyte (i.e. 1.0 M KOH). Additionally, an alkaline water splitting device has been assembled using porous Ni8Fe2 alloy as both anode and cathode materials. The system requires a cell voltage of 1.65 V to reach the 10 mA cm−2 current density for overall water splitting and maintains good stability for 25 h. The efficient electrocatalytic performance of the Ni8Fe2 alloy is owing to the unique porous microstructure, increased active sites and accelerated charge transfer. Consequently, the reaction kinetics of OER are significantly promoted.

In this research, 2205/Q235B clad plates were prepared by a vacuum hot rolling composite process. The effects of adding Fe, Ni, and Nb interlayers on the bonding interface structures and the shear strengths of the clad steel plates were studied. The results showed that 2205 duplex stainless steel and the three interlayers produced a large amount of plastic deformation and low-angle boundaries, and the main structures were the recrystallized and deformed grains. There were many recrystallized grains in the microstructure of the Q235B low-carbon steel due to the low deformation in the rolling process. The Fe interlayer had better wettability with the two kinds of steel, but the lower strength led to the reduction of shear strength by about 14 MPa compared with the original clad steel plate. The C element in the Q235B low-carbon steel easily diffused into the Fe interlayer, and the clad steel plate attained a poor corrosion resistance because a large decarburization area was formed. The Nb interlayer reacted with the Mo element in the 2205 duplex stainless steel to form an Nb–Mo binary alloy, which generated long-banded ferrite. The decarburization area was also produced because the Nb reacted with the C element in the Q235B to form hard and brittle NbCx. As a result, the shear strength was significantly reduced by about 282 MPa, and the corrosion resistance of the bonding surface was deteriorated. The Ni interlayer did not react with the alloy elements in both sides, and therefore effectively prevented element diffusion and improved the corrosion resistance of the bonding surface. Due to the low strength of the Ni interlayer and the increased number of bonding surfaces of the clad steel plates, the shear strength was reduced to some extent (about 40 MPa), but it still met the engineering application standards.

With the low redox potential of −3.04 V (vs SHE) and ultrahigh theoretical capacity of 3862 mAh g−1, lithium metal has been considered as promising anode material. However, lithium metal battery has ever suffered a trough in the past few decades due to its safety issues. Over the years, the limited energy density of the lithium‐ion battery cannot meet the growing demands of the advanced energy storage devices. Therefore, lithium metal anodes receive renewed attention, which have the potential to achieve high‐energy batteries. In this review, the history of the lithium anode is reviewed first. Then the failure mechanism of the lithium anode is analyzed, including dendrite, dead lithium, corrosion, and volume expansion of the lithium anode. Further, the strategies to alleviate the lithium anode issues in recent years are discussed emphatically. Eventually, remaining challenges of these strategies and possible research directions of lithium‐anode modification are presented to inspire innovation of lithium anode., The improvement of lithium anodes plays a great role in developing lithium metal batteries with high energy density. With the aim of enlighting the future directions of the researches on lithium anodes, the challenges and progress in the field of lithium anodes in recent years are presented.

Developing robust nonprecious electrocatalysts towards hydrogen/oxygen evolution reaction (HER/OER) is crucial for the spread of hydrogen energy industrialization. Here, we prepared a highly active and durable electrocatalyst of W single-atoms doped NiS0.5Se0.5 nanosheets@NiS0.5Se0.5 nanorods heterostructure (W-NiS0.5Se0.5). The W-NiS0.5Se0.5 exhibits superior catalytic activity for HER and OER with an ultralow overpotential (39, 106 mV for HER and 171, 239 mV for OER) and excellent long-term durability (500 h) at 10 and 100 mA cm− 2, outperforming commercial precious-metal catalysts and many other reported transition-metal-based compounds. The spin state of Ni was delocalized by introducing low spin-state of W single-atom, thus increasing the electron density of Ni 2p orbital, optimizing the adsorption/desorption process of H, significantly reducing the energy barrier of the rate-determining step (O* → OOH*), finally accelerating thermodynamics and kinetics of HER/OER. This work provides a rational feasible strategy to design single-atom catalysts for water splitting and develop advanced transition metal-based electrocatalysts via regulating delocalized spin states.

Designing high active, low cost and bifunctional electrocatalysts is urgent for developing clean energy storage and conversion systems. Transition metal selenides exhibit optimal electronic conductivity and tunable physicochemical properties, which endow them with potential for efficient electrocatalysts to facilitate the oxygen reduction and oxygen evolution reactions (ORR and OER). Herein, hollow NixCo0.85-xSe nanospheres were synthesized using a facile polyol based solution chemical method. The NixCo0.85-xSe exhibits an onset overpotential of 0.89 V for ORR, and an overpotential of 305 mV to achieve 10 mA cm−2 for OER. Moreover, the NixCo0.85-xSe based Zn-air battery displays remarkable specific capacity and durability. Such superior catalytic performances can be attributed to the synergistic effect, large specific surface area and enhanced electron transfer rate. This approach provides a new way to design highly efficient bifunctional electrocatalysts for electrochemical energy storage and utilization.

Considering the environmental problems caused by a large amount of cotton textile waste and its possible applications in flexible electrodes, it is very promising to reuse the cotton textile waste as an electrode material, reducing the cost of flexible electrodes and alleviating environmental problems. In this work, we present a rechargeable flexible Zn-air battery based on cotton textile waste, which employs Ni-metallized cotton textile waste (NMCTW) as a flexible substrate for Zn anodes and air cathodes. The transparent NiFe hydroxide thin film horizontally grown on the surface of the NMCTW substrate was synthesized in situ by the electrodeposition method, which exhibits excellent catalytic activity because of the high surface area of the two-dimensional (2D) thin film, large contact area between the thin film and substrate, and fast charge transport of the 2D thin-film structure. In view of the high catalytic performance of the NiFe hydroxide thin film, it was used as the catalytic material of the air cathode for the flexible Zn-air battery. The assembled Zn-air battery based on cotton textile waste demonstrated a good rate performance and outstanding charge and discharge cycling stability. The assembled Zn-air battery was applied to power the light-emitting diode, which exhibits exceptional flexibility and stable output power even under severe mechanical bending deformation, proving the feasibility for its application in flexible electronics.

The nanocomposite corrosion inhibitor with MoO42− intercalated ZnAl-LDH coating on the Fe3O4 surface was synthesized by ion exchange methods. The morphology, structure and magnetic properties of the composite were characterized by transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra and vibrating sample magnetometer. The release behavior of MoO42− and corrosion inhibition of the sample under “NO MF” (without external magnetic field) and “MF ON” modes (under external magnetic field) were measured by UV–vis spectroscopy, electrochemical tests and scanning electron microscopy. Calcination the composite after release test and redispersing the sintered products in Na2MoO4 solution, the composite was regenerated. The results show that the superparamagnetic nanocomposite inhibitor Fe3O4@MoO4-LDH presents well-defined core-shell structure. The release test revealed that for “NO MF” mode the release of MoO42− from Fe3O4@MoO4-LDH displayed smaller t0.5 (Time to reach half release equilibrium) of 4.25min and shorter time (3 h) to reach equilibrium with high release amount of 71.95% for 0.5 g/L nanocomposite. Under “MF ON” mode the release rate is slower with longer t0.5 (from 26.40min to 1.60 h for 0.5 g/L to 4.0 g/L nanocomposite, respectively), thus realizing sustained release up to 12 h. At the same time, the release amount decreases and the release time prolongs with the concentration increasing. Correspondingly, the MoO42− has a long-term excellent corrosion inhibition effect over 71.96% at 24 h on Q235 steel. For “NO MF”, the release route mainly contains the interlayer intraparticle diffusion between the LDH layers and interparticle diffusion among the outer LDH. While for “MF ON” mode, the diffusion between magnetic particles of corrosion inhibitor becomes important. The reconstructed inhibitor still maintains excellent superparamagnetic properties and high corrosion inhibition efficiency, up to 64.84% after five cycles.

The antibacterial properties of the microarc oxidation coating have gained wide attentions, and W-containing surface has been verified to be notably bactericidal. Herein, in this work, doping Na2WO4 into the electrolyte to prepare the antibacterial W-containing microarc oxidation coating is proposed for the first time. No obvious crystal phase related to hexavalent W exists in the coating, and sodium tungstate may transform into a trace amount of tungsten oxides and amorphous substances. The sodium tungstate plays a crucial role in the antibacterial capability of the coating, the W-containing coating exhibits conspicuous bactericidal performance against both planktonic and adherent Escherichia coli and Staphylococcus aureus. The antibacterial mechanism of the W-containing coating is first revealed to be linked to the extracellular and intracellular reactive oxygen species (ROS). The W-containing dissolved matters spontaneously trigger the formation of the extracellular ROS, which directly destroy the bacterial cytoderm and cytomembrane. Meanwhile, the nanoscale W-containing dissolved matters penetrate the cell wall, and stimulate the generation of intracellular ROS which interact with the cytoplasmic components. Ultimately, the bacteria die from the cooperative effects of the extracellular and intracellular ROS.

Alkaline zinc–air batteries are promising energy storage technologies with the advantages of low cost, ecological friendliness, and high energy density. However, the rechargeable zinc–air battery has not been used on a commercial scale because the zinc electrode suffers from critical problems such as passivation, dendrite growth, and hydrogen evolution reaction, which limit the practical applications of zinc–air batteries. Herein, the Perspective summaries the solutions to minimize the negative effects of zinc electrodes on discharge performance, cycling life, and shelf life. The future direction of academic research based on current studies of the existing challenges is proposed.

Stainless steels as proton exchange membrane fuel cell bipolar plates have received extensive attention in recent years. The pack chromizing layer was fabricated on 316L stainless steel to improve the corrosion resistance and electrical conductivity. The corrosion properties were investigated in 0.5 M H2SO4 + 2 ppm HF solution at 70 °C purged with hydrogen gas and air. Higher electrochemical impedance and more stable passive film were obtained by chromizing the 316L stainless steel. Potentiodynamic polarization results showed the corrosion current densities were reduced to 0.264 μA cm−2 and 0.222 μA cm−2 in two simulated operating environments. In addition, the interfacial contact resistance was decreased to 1.4 mΩ⋅cm2 under the compaction force of 140 N⋅cm−2 and maintained at low values after potentiostatic polarization for 4 h. The excellent corrosion and conductive performances could be attributed to the chromium carbides and high alloying element content in chromizing layer.

Flexible zinc-air batteries (ZABs) have been considered as one of the most outstanding energy storage devices for flexible and portable electronics because of their superior energy density and environmental friendliness. As the "blood" of flexible ZABs, electrolytes play a significant role in determining their performance, such as discharge working time, cycling property, and shelf life. Herein, a novel polymer electrolyte based on quaternary ammonium hydroxides is first applied in flexible zinc-air batteries. Tetraethylammonium hydroxide (TEAOH) is innovatively used as the ionic conductor with poly(vinyl alcohol) (PVA) as the polymer host in the polymer electrolyte and exhibits a good water retention capability, resulting in not only a good shelf life but also a good working life of the flexible zinc-air batteries. The fabricated polymer electrolyte maintains its high ionic conductivity of 30 mS cm

Exploring efficient bifunctional oxygen electrocatalysts is a critical element for developing high-power-density metal-air batteries. Here, we propose an interface and oxygen vacancy engineering strategy to integrate subtle lattice distortions, oxygen vacancies, and nanopores on the surface of NixCo1-xSe2-O interface nanocrystals, which exhibit efficient bifunctional catalytic performances for oxygen evolution and reduction. The results from X-ray absorption spectroscopy and electron spin resonance spectroscopy demonstrate that the defect structure can enlarge the number of active sites for electrocatalytic performances. Flexible Zn-air battery using NixCo1-xSe2-O as a cathode displays large specific capacity and remarkable stability even after twisting at any angle, thus showing potential for wearable and portable electronic device application. The implementation of our method provides a powerful strategy for preparing advanced catalysts for energy utilization.

Surfacing layers on H13 hot-working die steel for the repair and manufacture of structural components using submerged arc welding (SAW) have been tempered at 350 ℃, 450 ℃, 550 ℃ and 650 ℃ for 2 h. The impact toughness of specimens tempered at 350 ℃ were increased significantly, with their microhardness and wear resistance improved due to a decrease in welding defects and secondary hardening caused by the precipitation of carbide. Tempering at 450 ℃ resulted in refinement of microstructure, with a large amount of tempered martensite being formed that significantly improved the microhardness, wear resistance and impact toughness. However, it was found that these mechanical properties were decreased at 550 ℃ due to grain growth. Formation of large numbers of carbide particles resulted in hard abrasive specimens that were difficult to cut, resulted in an overall increase in wear resistance when the specimens were tempered at 650 ℃.

Identification of the active center is pivotal to manipulate the catalyst design for the oxygen evolution reaction. Herein, sulfur was introduced to partly occupy oxygen location in the surface structure of cobalt (II) oxide. The heterogenous ‘O-Co-S’ sites brought an enhanced oxygen evolution activity, including a five-fold intrinsic activity improvement and a reduced overpotential of 66 mV at 10 mA cm−2. Experimental and theoretical investigations reveal that the electronegativity difference between sulfur and oxygen induce the Co 3d electron accumulation along the Co-O bond. This orientated distortion optimizes the adsorption behaviors to oxygen-containing species and also favors energy band more continuous to promote electron transfer, thereby leading to improved electrochemical performance. This work provides the atomic-level understanding of the nature of active sites, which would shed light on the rational design and regulation of other material systems for advanced energy storage and conversion devices.