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The carbon layers wrapped CoFe alloy (C/CoFe-30-650) exhibits high bifunctional catalysis for both ORR and OER, and the rechargeable ZABs with this catalyst has an excellent stability during 20,000 charging-discharging cycles.

Rational electrode design is crucial to promote the performance of the hydrogen evolution reaction (HER) via further enhancing the activity, stability, and utilization of platinum (Pt) in an alkaline electrolyte. Herein, a binder-free low-Pt-content HER electrode, Pt (∼20 μg cm–2) decorated on nickel hydroxide grown on nickel foam (Pt-Ni(OH)2-2h-NF20), is fabricated at near room temperature in a test tube. To lower the ohmic resistance, for the first time, the Pt nanoparticles were location-selectively anchored on the bottom of height-controlled vertical Ni(OH)2nanosheets via utilizing the mass transfer resistance of the dense Ni(OH)2film for chloroplatinate. Furthermore, the excellent mass transfer, high specific surface area of Pt, synergistic effect between Pt with Ni(OH)2, and stable structure together prompt the resulting electrode with a special structure to exhibit superior HER electrocatalytic activity and stability in 1 M KOH. Typically, this electrode reaches a current density of 35.9 mA cm–2at an overpotential of 100 mV, which is over 8 times higher than that of commercial Pt/C, and the overpotential only increases by 20 mV at 100 mA cm–2over 150,000 s of stability test. Benefiting from the simple fabrication process, the electrode with an area of 840 cm2was successfully prepared with a steady overpotential of 370 mV at 1000 mA cm–2and increased potential of 23 mV over 50 h of stability test.

Transition metal phosphides are a class of promising electrocatalysts for hydrogen evolution reaction (HER) to replace noble metals. In this work, we for the first time synthesize carbon supported CoP nanoparticles with the average particle sizes from 3.3 to 9.2 nm, via a solvothermal process followed by low-temperature topological phosphorization, and the size-dependent HER activity of the CoP is investigated by virtue of TEM, XRD, XPS and the electrochemical techniques. It is discovered that the 9.2nm-CoP particles possess high intrinsic HER catalytic activity as compared to the 3.3nm-CoP, although the smaller one displays a high mass activity due to the large surface area. Detailed studies manifest that the small CoP particles suffer from serious oxidation once exposing to air. In contrast, most cobalt remains in the quasi-metallic state in the relatively large CoP particles, which is beneficial for the desorption of Hads, the rate determining step of the HER process over CoP surface. In addition, the low charge transfer resistance across the liquid/solid interfaces also contributes to the excellent HER activity of the relatively large CoP particles.

Hydrogen is a promising sustainable energy to replace fossil fuels owning to its high specific energy and environmental friendliness. Alkaline water electrolysis has been considered as one of the most prospective technologies for large scale hydrogen production. To boost the sluggish kinetics of hydrogen evolution reaction (HER) in alkaline media, abundant materials have been designed and fabricated. Herein, we summarize the key achievements in the development of layered transition-metal hydroxides [TM(OH)x] for efficient alkaline HER. Based on the structure of TM(OH)x, the mechanism of synergistic effect between TM(OH)xand HER active materials is illuminated firstly. Then, recent progress of TM(OH)x-based HER catalysts to optimize the synergistic effect are categorized as TM(OH)xand active materials, including species, structure, morphology and interaction relationship. Furthermore, TM(OH)x-based overall water splitting electrocatalysts and electrodes are summarized in the design principles for high activity and stability. Finally, some of key challenges for further developments and applications of hydrogen production are proposed.

An efficient and durable air cathode is of great importance for the commercial application of zinc‐air fuel cell. In this work, a new air cathode with the hydrophobic pores distributed continuously and in gradient was prepared and characterized by the scanning electron microscope (SEM) combined with energy dispersive X‐ray spectroscopy (EDS). Compared with traditional air cathode, our new cathode exhibits attractive performance and lifetime, by which the maximum power density of 252 mW cm−2and a stable discharge of 3600 h at 50 mA cm−2are presented in zinc‐air fuel cells. Further investigation shows that the unique pores with the adequate size and hydrophobic property in current collector layer for the new cathode are helpful to prevent the water accumulation, and inhibit the formation of carbonate. Improving stability! A new air cathode with the hydrophobic pores distributed continuously and in gradient was proposed and successfully prepared for zinc‐air fuel cells. The new cathode shows high performance and long lifetime for the maximum power density 252 mW cm−2and stably 3600 h discharge in a zinc‐air fuel cells. And this cathode efficiently prevents the accumulation of electrolyte and the formation of carbonate inside the electrodes, and is a potential candidate for zinc‐air fuel cells.

Rechargeable Zn-air batteries (ZABs) constitute promising next-energy conversion and storage systems due to their low cost, intrinsic safety, and feasibility to fabricate high energy density and stable charge and discharge voltage. Nevertheless, the most significant challenge of rechargeable ZABs is relatively high over potential owing to the sluggish kinetics of oxygen reactions on the air cathode, requiring high-performance noble-metal-free bifunctional electrocatalysts with highly cost-effective. Herein, we developed a facile and scalable coprecipitation strategy to successfully prepare CuO/Co3O4@CNTs catalysts for bifunctional oxygen electrocatalysts. This unique strategy enables CuO/Co3O4nanoparticles to be uniformly grown on CNTs and the simultaneous pyrolysis process results in the generation of ultrafine CuO/Co3O4heterostructures. Contributed to an abundance of heterostructures, the oxygen vacancies and unsaturated chemical bonds in the interface were generated in CuO/Co3O4. Consequently, the CuO/Co3O4@CNTs delivered bifunctional activity of ΔE of 0.78 V and good stability that can maintain 1000 h charge and discharge cycles.

With the increasing demand of energy storage towards increasing the use of renewable energy technologies, electrochemical systems with low cost, high safety levels, and low environmental impact are critically needed. Zinc–air/oxygen batteries, which were always considered to be cheap, are losing their competitive advantages due to poor cyclic performance and energy efficiency. Herein, an effective strategy for oxygen recycling, which reduces the cost of oxygen to as low as ¢ 0.2 kWh−1per cycle, is reported. With the use of oxygen, the performance of zinc–oxygen batteries is largely increased, with a maximum power density of 290 mW cm−2, stable cycling for more than 1500 cycles, an average energy density of 60 %, and elimination of carbonates. A 1 kW/1 kWh zinc–oxygen battery system is also integrated and exhibits a satisfactory energy efficiency of 58 % and a high working power density of 75 mW cm−2. Don't let the air out! An effective strategy of oxygen recycling is proposed to reduce the cost of oxygen per cycle. With the use of oxygen instead of air, the performance of zinc–oxygen batteries is increased with improved cycling stability. The integration of an oxygen recycling system and a zinc–oxygen battery system yields a satisfactory energy‐storage device.

Porous solids are widely utilized in natural and engineering systems due to their exceptional specific mechanical response and customizable properties. However, lightweight cellular solids often undergo severe localized deformation, resulting in catastrophic failure. This limitation undermines their damage resistance, thereby limiting their use primarily within small strain regimes. To address this issue, we drew inspiration from the unique structural features and damage-tolerant characteristics of the knobby starfish, leading us to the design of hierarchical diamond–triply periodic minimal surface (TPMS) lattices on two levels. We carried out a thorough examination of their mechanical behaviors, energy absorption, and damage tolerance using both experimental methods and finite element models. The designed hierarchical diamond lattices displayed stable elastoplastic-like deformation across large strain, along with excellent damage resistance, maintaining a stiffness and strength of over 57% of the initial value after four cycles of compression. Simulations aligned well with experimental results, showing a progressive transition in the deformation behavior of the designed lattices from bending-dominated to stretching-dominated as the thickness of the micro-lattice increased. However, there are no significant changes in the deformation behavior for the shear modulus. Overall, the designed hierarchical diamond lattices demonstrated superior specific energy absorption of 2.62J/g and remarkable damage tolerance compared to state-of-the-art lattices. This study aims to provide new insights into the design of hierarchically structured cellular materials.

Zinc metal anodes suffer from severe dendrite growth and parasitic hydrogen evolution in aqueous electrolyte, which impede their practical application. Herein, a negatively charged protection layer combining metal-organic framework (UIO-66-SO3H) and flexible sulfonated poly (ether ether ketone) (SPEEK) binder is introduced on the Zn anode to suppress dendrites and side reactions (denoted as USL-Zn). The USL film with zincophilic –SO3−functional groups uniformizes the Zn2+flux and guides even Zn deposition. In addition, this protective layer functions as a physical barrier and manipulates the local electrolyte structure to mitigate the hydrogen evolution reaction and passivation on Zn anode surface. As a result, USL-Zn electrodes deliver high cycling stability at various current densities and capacities (700 h at 5 mA cm−2, 5 mAh cm−2and 300 h at 10 mA cm−2, 10 mAh cm−2), and enable high average Coulombic efficiency of 99.34 % (1 mA cm−2for 1 h). Moreover, enhanced rate capacity and prolonged lifespan can be attained in Zn//VO2full cells. This proposed strategy provides insight into the design of SEI layers in aqueous batteries and promotes the potential application of Zn metal batteries.

Carbon supported gold-iridium composite (AuIr/C) was synthesized by a facile one-step process and was investigated as the bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The physical properties of the AuIr/C composite were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Although the Au and Ir in the AuIr/C did not form alloy, it is clear that the introduction of Ir decreases the average Au particle size to 4.2nm compared to that in the Au/C (10.1nm). By systematical analysis on chemical state of metal surface via XPS and the electrochemical results, it was found that the Au surface for the Au/C can be activated by potential cycling from 0.12V to 1.72V, resulting in the increased surface roughness of Au, thus improving the ORR activity. By the same potential cycling, the Ir surface of the Ir/C was irreversibly oxidized, leading to degraded ORR activity but uninfluenced OER activity. For the AuIr/C, Ir protects Au against being oxidized due to the lower electronegativity of Ir. Combining the advantages of Au and Ir in catalyzing ORR and OER, the AuIr/C catalyst displays an enhanced catalytic activity to the ORR and a comparable OER activity. In the 50-cycle accelerated aging test for the ORR and OER, the AuIr/C displayed a satisfied stability, suggesting that the AuIr/C catalyst is a potential bifunctional catalyst for the oxygen electrode.

Abstract: Ceria–alumina composite supports were prepared by the co-precipitation (cop), impregnation (imp) or deposition–precipitation (dp) methods. Co–Mo catalysts supported on these composite supports were prepared by the imp method and their catalytic activities for sulfur-resistant methanation of synthesis gas were investigated. The catalysts were characterized by nitrogen adsorption, X-ray diffraction (XRD), and hydrogen temperature-programmed reduction (TPR). It was found that the preparation method of ceria–alumina composite support had a marked influence on the surface area, the interaction between ceria and alumina, and the catalytic performance for sulfur-resistant methanation. Among them, the ceria–alumina composite support prepared by dp method achieves the best methanation activity due to its smaller ceria particle size, better ceria dispersion, weak interaction between ceria–alumina as suggested by XRD and TPR results.

The gas diffusion electrode (GDE) represents the most significant component in metal–air batteries (MABs). It is essential to understand the underlying behaviors of GDE and optimize its performance. Herein, a polarization separation method from total polarization curve to single activation, ohmic, and mass transport polarizations of GDE in MABs is proposed for the first time, which is then applied in the investigation of detailed polarization behaviors of the GDE by changing the fabrication parameters. As the polytetrafluoroethylene contents in the catalyst and gas diffusion layers and pressing pressure are adjusted, hydrophobicity, porosity, coverage, and thickness are changed to influence the performance of GDE. Through this analysis, a detailed understanding of the structure–performance relationship of GDE is achieved to improve the electrode design, architecture, and fabrication. Herein, a polarization separation method from total polarization curve to single polarization of gas diffusion electrode (GDE) in metal–air batteries is first proposed, which is applied in the investigation of detailed polarization behaviors of the GDE by changing the fabrication parameters. Through this analysis, the structure–performance relationship of GDE can be achieved, to improve the electrode performance.

Transformer is a key equipment in the power system, and it is very important to accurately evaluate its operating state. In this paper, a new method is proposed to evaluate the operating state of the power transformer based on the genetic projection pursuit model. The proposed method can provide a more objective evaluation result for the health condition of the transformers compared with the traditional methods. Firstly, a three-layer evaluation index system is established with the precautionary test, oil chromatographic analysis and insulating oil properties as the core content. And then, the grading standard of the lowest level index in the indicator system is established. Secondly, the genetic projection pursuit model is used in combination with the grading standard to obtain the intermediate layer evaluation results, which overcomes the disadvantages of the traditional transformer evaluation method which is greatly influenced by subjective factors. Finally, the eigenvalue weighting method is used to integrate the intermediate layer evaluation results to obtain the final result. Case study results show that the evaluation method of transformer operating state based on genetic projection pursuit model is reasonable and effective.