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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.

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.

We have examined the ability of the newly synthesized thioalkyl and thiophenyl (SR) BODIPYs to generate the excited triplet state (T1) using the laser flash photolysis technique. Compared to the un...

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.

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.

Efficient and selective heavy atom-free singlet oxygen photosensitizers (HAFPS) are highly desirable for chemistry, pharmaceutical sciences, phototherapy, and environmental sciences. The donor–acce...

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.

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 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.

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.

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.

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.

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.

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.

The angular velocity data of Fiber-Optic Gyro (FOG) are key signals to trajectory calculation for a FOG-based curve measuring system. The shocks from bumps on the route will contaminate the signal and finally drift the calculated trajectory. An optimized processing strategy on the contaminated signals is able to suppress the drifting with almost no trajectory distortion. In this paper, the signals from FOG have been processed by using median filtering (MF), Empirical Mode Decomposition (EMD) and the combined method of EMD and Independent Component Analysis (ICA). The experiments are performed under different conditions. The frequency spectrum and deviation study before and after processing have been investigated to compare the performance of the employed strategies. The combined EMD and ICA method has shown the best performance on trajectory optimization and error suppression with almost no distortion.

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.

To examine if BODIPY-electron acceptor conjugates can generate excited triplet state and singlet oxygen efficiently via a photoinduced charge separation–charge recombination (CS-CR) mechanism, seve...

In this work, ZnMoO4/reduced graphene oxide (ZnMoO4/RGO) composite was successfully synthesized by a facile hydrothermal method. The morphology, structure and composition of obtained composite were studied by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS) and Raman spectra. Moreover, the loading amount and releasing behavior of ZnMoO4 in the ZnMoO4/RGO composite were determined by the thermo-gravimetric analysis (TGA) and UV–vis spectrophotometer respectively. The inhibition behavior and mechanism of ZnMoO4/RGO for Q235 steel in 3.5% NaCl solution were investigated by electrochemical impedance spectroscopy (EIS) and XPS techniques. The results show that the ZnMoO4 nanoparticles are successfully incorporated into RGO sheets and the loading amount of ZnMoO4 in ZnMoO4/RGO is 91.59%. The inhibition efficiency of Q235 steel in 3.5% NaCl + ZnMoO4/RGO solution is superior to that in 3.5% NaCl solution, and increases with the extending released time. The highest inhibition efficiency can be obtained as 87.50% at 72 h. The higher inhibition efficiency in the ZnMoO4/RGO contained solution is mainly attributed to the synergy effect of RGO, MoO42− and Zn2+, which can form a protective film on the surface of Q235 steel.

P-type Cu2O is an advantageous photocatalyst as the appropriate bandgap structure and low-cost. However, poor photocatalytic and instability of such promising material is still a great challenge. Here the core-shell Cu7S4-coated Cu2O nanocubes (Cu2O/Cu7S4 NCs) were successfully synthesized by solution method coupled with anion exchange, and were firstly employed to hydrogen evolution reaction (HER). The resultant integrated structure of Cu2O/Cu7S4 NCs exhibited apparent improved photocatalytic hydrogen evolution activity compared with Cu2O photocatalyst. Particularly, Cu2O/Cu7S4 NCs had a high hydrogen production rate of 1689.00 μmol g−1 h−1 under full spectra irradiation with additive of Na2SO3, which was higher than that of Cu2O NCs with a factor of 1.71 times. Excellent synergistic effect of Cu2O and Cu7S4 can be responsible for the improved hydrogen evolution properties, namely, the presence of Cu7S4 with localized surface plasma resonance (LSPR) can promote the photogenerated electrons transfer from the Cu2O surface, prolong the photogenerated holes lifetime, accelerate the separation of photogenerated electrons and holes, and ameliorate the photoelectric properties of semiconductors. The in situ formed multifunctional Cu7S4 layer offers a promising avenue to design photocathodes rationally for photocatalytic water reduction.

Sulfur induced corrosion (SIC) is an important issue taking place in the heat transfer crevices between steam generator (SG) tubing and tube supports in pressurized water reactors (PWRs). Contemporary aspects of passivity, passivity breakdown, and localized corrosion induced by sulfur are reviewed, with an emphasis on corrosion mechanism at micro scale. The passive film properties can be altered in the presence of sulfur, these properties including semiconductivity, defect density, film dissolution rate and film composition. This review is also instructive to other corrosion systems including paper and petroleum industry, where the SIC is a ubiquitous phenomenon.

To test the tunability of charge transfer (CT)-based BODIPY photosensitizers in generating singlet oxygen (1Δg), twelve meso-phenyl-BODIPY (donor-acceptor) type compounds have been synthesized and fully characterized, in which the phenyl moiety is modified with respective 0, 1, 2 and 3 methoxy groups to increase its electron-donating ability. The UV-Vis absorption spectra, fluorescence emission spectra, fluorescence quantum yield, fluorescence lifetime, excited triplet state formation, and singlet oxygen formation properties are measured. DFT quantum chemical computation is also carried out to explain the experiments. The occurrence of intra-molecular CT is confirmed by UV-Vis absorption, fluorescence properties and quantum chemical computation. The triplet excited state formation is evidenced by laser flash photolysis technique. The quantitative photosensitized singlet oxygen formation is demonstrated by DPBF (diphenylisobenzofuran) chemical trapping method. This type of BODIPY CT photosensitizers show good tunability in generating singlet oxygen (1Δg). When the number of methoxy group on the donor is increased (so that CT is enhanced), the efficiency of singlet oxygen generation becomes higher from 0.070 to 0.30. When solvent polarity is increased (CT is also enhanced), the efficiency of singlet oxygen generation is also increased significantly. The increase in singlet oxygen generation is accompanied by the decrease in fluorescence quantum yield and fluorescence lifetime values. These facts show that a higher CT efficiency in a simple phenyl-BODIPY donor-acceptor conjugate can lead to significant higher quantum yield of singlet oxygen generation. These results are useful in designing novel CT-based heavy-atom-free photosensitizers for photodynamic therapy of tumor.

Developing high-performance bifunctional catalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential to enhance water splitting efficiency for large-scale hydrogen production. Neither noble metal Pt nor transition metal compounds show satisfactory performances for both HER and OER simultaneously. Here, we prepared a three-dimensional Pt-Ni3Se2@NiOOH/NF (PNOF) hybrid catalyst via in-situ growth strategy. Benefitting from the self-supported structure and oxygen vacancies on the surface of NiOOH nanosheets, the PNOF electrode shows remarkably catalytic performance for dual HER and OER. The overall water electrolyzer using PNOF as anode and cathode can achieve a current density of 10 mA cm−2 at a low voltage of 1.52 V with excellent long-term stability, which is superior to precious metal catalysts of Pt/C and Ir/C. This study provides a promising strategy for preparing bifunctional catalysts with high performance.

Bulk Al-doped carboxymethyl cellulose aerogels were obtained via a facile slow-gel method and freeze-drying technology. In this method, the cross-linker Al3+ was released slowly and completely with enough d -(+)-gluconic acid δ-lactone as a sustained-release agent. Depended on controlled releasing of Al3+, the reaction speed between Al3+ and carboxyl groups was controlled and Al3+ was well-distributed in the aerogels. The coordination type between Al3+ and carboxymethyl cellulose was the bidentate bridging coordination. By adjusting the amount of Al3+ and the degree of substitution of carboxymethyl cellulose, interconnected network and closely packed sheet-like structure presented, respectively. According to the nitrogen adsorption-desorption isotherms, the aerogels were a kind of mesoporous material with pore blocking or cavitation. In addition, the aerogels exhibited outstanding weight-bearing capacity and excellent flame retardancy. This work provided a valuable reference for doping metal ions into polysaccharide aerogels and expanding the application fields of aerogels.

A novel multi-corrosion inhibitors-halloysite nanocomposite was successfully synthesized by stepwise loading 2-Mercaptobenzothiazole (MBT) and benzotriazole (BTA) into halloysite nanotubes (HNTs), then the insoluble Cu-BTA complex was introduced at the end of HNTs (defined as “Cu-BTA-MBT-HNTs”) to control the release rate of MBT and BTA. The prepared Cu-BTA-MBT-HNTs can not only reduce the release rate of MBT and BTA for achieving the sustained release effect, but also an acid-response complex corrosion inhibitors. Moreover, the Q235 steel in 3.5% NaCl + Cu-BTA-MBT-HNTs solution owns high inhibition efficiency. Therefore, the Cu-BTA-MBT-HNTs can be a very promising multi-corrosion inhibitors-halloysite nanocomposite.

Carbon-based anode materials hold a promising future for sodium-ion batteries (SIBs) due to their natural abundance and low cost of development. In spite of carbon's important role in the commercialization of lithium-ion batteries (LIBs), further exploration is necessary in order to find high-performance, high-rate carbon anode materials for SIBs. A honeycomb-like, nitrogen-rich (17.72 at%), hierarchically porous, and highly disordered carbonaceous material (N-HC) with an expanded interlayer distance (0.44 nm in average) is synthesized by spray drying and subsequent pyrolysis under flowing NH3. The hierarchically porous structure and rich nitrogen doping result in a large specific surface area (722 m2 g−1), more defects and active sites, and greater functional interface accessibility for the active porous carbonaceous material and electrolyte. When N-HC is used as the anode material for SIBs, the batteries display favorable discharge capacities (255.9 mA h g−1 in the 3000th cycle at 500 mA g−1) and good capacitive-energy-storage behavior (67% at a scan rate of 0.5 mV s−1) with excellent high-rate performance and ultra-stable cyclability over 10,000 cycles at 5000 mA g−1. Our results show that the combination of the hierarchically porous structure and nitrogen doping leads to improved energy storage by increasing the capacitive energy storage, which enhances the high-rate performance of N-HC. To further enhance the performance of the material, an electrical pretreatment is employed to increase the initial Coulombic efficiency of N-HC to 79.5%, a record high for an SIB cell. A full cell with an N-HC anode and a Na3V2(PO4)3/C cathode shows a high capacity with a favorable cyclability (238.7 mA h g−1 after 100 cycles at 100 mA g−1 and a capacity retention of 95.3% compared to the second cycle).

The electrochemical reactivity of a defect in organic coating was investigated by electrochemical noise (EN) and scanning electrochemical microscopy (SECM). Time dependent EN spectra and SECM image on a metal with defective organic coating was measured, and corresponding EN frequency domain spectra and probe approach curves (PACs) were used to obtain electrochemical reactivity information within the coating defects. All time domain and frequency domain analyses, and SECM measurements were successful indicators of corrosion intensity within the defect. The amplitude of electrochemical current noise (ECN) and the low-frequency plateau of the power spectral density (PSD) WL increased significantly with corrosion intensity.

An electrochemical sensor is developed to evaluate the shelf life of lacquered tinplate cans by using open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiostatic step techniques. The voltage and current detection precision of measurement system are 0.25 mV and 500 pA. The evolution of OCP, coating resistance, charge transfer resistance, and current response after potentiostatic step can be used as indicators for shelf life evaluation. Through establishing the electrochemical equivalent circuits (EECs), the change of the corrosion resistance over time is formulated and its correlation with shelf life is elucidated. The results show that electrochemical methods are successfully applied in fast shelf-life assessment of metal packaging cans.

Zinc–air batteries (ZABs) with high energy density and low cost have ignited tremendous interest in meeting the ever-growing demands for flexible and portable electronics. As the “blood” of a flexible ZAB, the semi-solid/solid-state electrolyte plays a critical role in the battery performance such as cycling performance, rate characteristics and power output. Herein, a novel porous-structured poly (vinyl alcohol) (PVA)-based nanocomposite gel polymer electrolyte (GPE) with the optimum addition of silica (SiO2) was synthesized and utilized in a bendable sandwich-type ZAB. The fabricated porous PVA-based nanocomposite GPE exhibited a high ionic conductivity (57.3 mS cm–1), excellent water retention capability as well as improved thermal and mechanical properties under ambient condition, with which the assembled flexible ZAB presented excellent cycle stability, discharge performance and power density. Furthermore, the flexible porous PVA–SiO2 based ZAB sets could power a light-emitting diode screen, a handheld electric fan, or even a mobile phone, demonstrating its promising potential for high-performance ZABs with high safety, cost-effectiveness, and excellent flexibility.

The exploitation of economical and highly efficient bifunctional electrocatalysts to promote oxygen evolution and hydrogen evolution reactions (OER and HER) for water splitting devices is urgently needed. Herein, a series of NiSx (i.e., NiS, Ni3S2, NiS2) nanocrystals with controllable phase and composition have been synthesized via a facile polyol solution process and the corresponding electrocatalytic properties towards OER and HER have been systematically investigated. Electrochemical results reveal that Ni3S2 exhibits superior OER and HER performance to NiS and NiS2, achieving 1.63 V to reach a current density of 10 mA cm-2 in the overall water splitting device, which is comparable to that of noble metal catalysts. Experimental and theoretical calculation investigations demonstrate that the remarkable catalytic properties of Ni3S2 could be attributed to the intrinsic metallic conductivity, abundant active sites and optimal Gibbs free-energy for catalyst-H* for HER. Moreover, a thicker layer of catalytically active species of NiOOH was generated on the surface of Ni3S2 due to the higher proportion of Ni, leading to a better OER performance. These results should shed light on the design and development of low cost and efficient transition metal chalcogenide electrocatalysts through phase and composition regulation for advanced electrochemical energy conversion devices.

A novel double-layered antibacterial coating was fabricated on pure titanium (Ti) via a simple three-step electrodeposition process. Scanning electronic microscopy (SEM) images show that the coating was constructed with the inner layer of TiO2 nanotubes doped with silver nanoparticles (TNTs/Ag) and the outer layer of chitosan–gelatin mixture with zinc oxide and silver nanoparticles (CS–Gel–Ag–ZnO). In comparison, we also investigated the composition, structure and antibacterial properties of pure Ti coated with TNTs, TNTs/Ag or TNTs/Ag + CS–Gel–Ag–ZnO, respectively. The TNTs was about 100 nm wide and 240 nm to 370 nm tall, and most Ag nanoparticles (Ag NPs) with diameter smaller than 20 nm were successfully deposited inside the tubes. The CS–Gel–Ag–ZnO layer was continuous and uniform. Antibacterial activity against planktonic and adherent bacteria were both investigated. Agar diffusion test against Staphylococcus aureus (S. aureus) shows improved antibacterial capacity of the TNTs/Ag + CS–Gel–Ag–ZnO coating, with a clear zone of inhibition (ZOI) up to 14.5 mm wide. Dead adherent bacteria were found on the surface by SEM. The antibacterial rate against planktonic S. aureus was as high as 99.2% over the 24 h incubation period.

Composite materials made up of non-precious metal oxide and N-doped carbon materials are great potential bifunctional catalysts for Zn–air batteries (ZABs) owing to the synergistic effect caused by the two components. Herein, Co3O4 nanoparticles supported on N-doped electrospun carbon nanofibers (CNFs) with superior bifunctional activity for the ORR/OER and remarkable electrocatalytic stability in an alkaline electrolyte are designed and synthesized. In addition, the hybrid electrocatalyst further promotes the rechargeable ZABs with a low overpotential, high efficiency and prolonged cycling life, superior to those using precious metal catalysts of Pt/C and IrO2. Such a remarkable bifunctional catalytic activity is attributed to the enhanced charge transfer capability, abundant exposed catalytically active sites and the synergistic effect among the Co3O4 nanoparticles and CNFs. This work should provide a convenient pathway for the design of non-precious metal and carbon hybrid materials that can be employed as efficient electrocatalysts for large-scale implementations of renewable energy conversion devices.

This work aims to develop field corrosion detection method for identifying the defect levels in organic coatings by using electrochemical noise (EN) measured at Singe Cell (SC) mode. An electrochemical sensor was used for defects identification, the results indicate that, as the defect levels rise, the amplitudes of the electrochemical current noise (ECN) increase. Further data analysis based on power spectral density (PSD), and discrete wavelet analysis confirmed that white noise level WL, and wavelet energy distribution can successfully discriminate the levels of protectivity of the organic coating.

Clarifying and controlling the surface catalytic active sites is at the heart of developing low-cost effective bifunctional oxygen catalysts to replace precious metals for metal–air batteries. Herein, a shape-control of hexagon nickel cobalt oxide spinel nanosheets was reported to engineer the surface metal active sites for enhanced electrocatalysis of oxygen evolution and oxygen reduction reactions (OER/ORR). Specifically, through simply tuning annealing temperature, different Ni3+/Ni2+ and Co3+/Co2+ atomic configurations on the nickel cobalt oxide surface were controllably synthesized. Electrochemical results show that the oxide treated at 250 °C (NCO-250) with the highest value of Ni3+/Ni2+ sites and the lowest value of Co3+/Co2+ sites exhibits superior OER/ORR activity in alkaline electrolytes and better discharge/charge performance in Zn–air batteries among all the samples. The optimized surface active site configuration of the NCO-250 sample leads to the optimal energy of adsorption, activation, and...

The corrosion behaviors of X65 steel in the artificial seawater at different hydrostatic pressures are investigated by potentiodynamic polarization measurements, electrochemical impedance spectroscopy measurements and weight loss measurements. The corroded morphologies and the corrosion products are also investigated by scanning electron microscopy, X-ray diffraction analysis and Raman analysis. The results show that the corrosion current increases as the hydrostatic pressure increases. The charge transfer resistance decreases as the hydrostatic pressure increases. The corrosion products are mainly composed of γ-FeOOH and Fe3O4 at the atmospheric pressure, while the main components are γ-FeOOH, Fe3O4, and γ-Fe2O3 at the high pressure. The hydrostatic pressure accelerates the corrosion of X65 steel due to its effect on the chemical and physical properties of corrosion products, including the promoted reduction of γ-FeOOH and the wider and deeper cracks on the corrosion products layer.