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Hetero-anionic oxysulfides, possessing an optimized electronic structure and excellent intrinsic activity, are identified as the actual and stable active site of sulfide pre-electrocatalysts for oxygen evolution.

A retrospect of the history of zinc–air batteries is provided, including four historical stages regarding the birth, the rising, the stagnancy, and the revival of zinc–air batteries.

A PVA-borax-IL ternary hydrogel electrolyte was developed for visual flexible electrochromic strain sensors to monitor human activity.

Lithium-sulfur (Li-S) batteries constitute promising next-generation energy storage devices due to the ultrahigh theoretical energy density of 2600 Wh kg-1. However, the multiphase sulfur redox reactions with sophisticated homogeneous and heterogeneous electrochemical processes are sluggish in kinetics, thus requiring targeted and high-efficient electrocatalysts. Herein, a semi-immobilized molecular electrocatalyst is designed to tailor the characters of the sulfur redox reactions in working Li-S batteries. Specifically, porphyrin active sites are covalently grafted onto conductive and flexible polypyrrole linkers on graphene current collectors. The electrocatalyst with the semi-immobilized active sites exhibits homogeneous and heterogeneous functions simultaneously, performing enhanced redox kinetics and a regulated phase transition mode. The efficiency of the semi-immobilizing strategy is further verified in practical Li-S batteries that realize superior rate performances and long lifespan as well as a 343 Wh kg-1 high-energy-density Li-S pouch cell. This contribution not only proposes an efficient semi-immobilizing electrocatalyst design strategy to promote the Li-S battery performances but also inspires electrocatalyst development facing analogous multiphase electrochemical energy processes.

Oxygen reduction reaction (ORR) constitutes the core process of many energy storage and conversion devices including metal–air batteries and fuel cells. However, the kinetics of ORR is very sluggish and thus high-performance ORR electrocatalysts are highly regarded. Despite recent progress on minimizing the ORR half-wave potential as the current evaluation indicator, in-depth quantitative kinetic analysis on overall ORR electrocatalytic performance remains insufficiently emphasized. In this paper, a quantitative kinetic analysis method is proposed to afford decoupled kinetic information from linear sweep voltammetry profiles on the basis of the Koutecky–Levich equation. Independent parameters regarding exchange current density, electron transfer number, and electrochemical active surface area can be respectively determined following the proposed method. This quantitative kinetic analysis method is expected to promote understanding of the electrocatalytic effect and point out further optimization direction for ORR electrocatalysis.

Two new monoterpenoid indole alkaloids, taberibogines A and B (1 and 2), together with four known ones (3–6), were isolated from the stems of Tabernaemontana bovina. The structures of these compounds were elucidated using comprehensive spectroscopic analysis and quantum chemistry computational methods. Compounds 1–2 were evaluated for their inhibitory effects on LPS-induced NO production in RAW 264.7 macrophages.

Aqueous zinc-air batteries possess inherent safety and are especially commendable facing high-temperature working conditions. However, their working feasibility at high temperatures has seldom been investigated. Herein, the working feasibility of high-temperature zinc-air batteries is systemically investigated. The effects of temperature on air cathode, zinc anode, and aqueous electrolyte are decoupled to identify the favorable and unfavorable factors. Specifically, parasitic hydrogen evolution reaction strengthens at high temperatures and leads to declined anode Faraday efficiency, which is identified as the main bottleneck. Moreover, zinc-air batteries demonstrate cycling feasibility at 80 °C. This work reveals the potential of zinc-air batteries to satisfy energy storage at high temperatures and guides further development of advanced batteries towards harsh working conditions.

Oxygen reduction and evolution reactions constitute the core process of many vital energy storage or conversion techniques. However, the kinetic sluggishness of the oxygen redox reactions and heavy reliance on noble-metal-based electrocatalysts strongly limit the energy efficiency of the related devices. Developing high-performance noble-metal-free bifunctional ORR and OER electrocatalysts has gained worldwide attention, where much important progress has been made during the last decade. This review systematically addresses the design principles to obtain high-performance noble-metal-free bifunctional oxygen electrocatalysts by emphasizing strategies of both intrinsic activity regulation and active site integration. A statistical analysis of the reported bifunctional electrocatalysts is further carried out to reveal the composition-performance relationship and guide further exploration of emerging candidates. Finally, perspectives for developing advanced bifunctional oxygen electrocatalysts and aqueous rechargeable metal-air batteries are proposed.

Rechargeable zinc-air batteries call for high-performance bifunctional oxygen electrocatalysts. Transition metal single-atom catalysts constitute a promising candidate considering their maximum atom efficiency and high intrinsic activity. However, the fabrication of atomically dispersed transition metal sites is highly challenging, creating a need for for new design strategies and synthesis methods. Here, a clicking confinement strategy is proposed to efficiently predisperse transitional metal atoms in a precursor directed by click chemistry and ensure successful construction of abundant single-atom sites. Concretely, cobalt-coordinated porphyrin units are covalently clicked on the substrate for the confinement of the cobalt atoms and affording a Co-N-C electrocatalyst. The Co-N-C electrocatalyst exhibits impressive bifunctional oxygen electrocatalytic performances with an activity indicator Δ E of 0.79 V. This work extends the approach to prepare transition metal single-atom sites for efficient bifunctional oxygen electrocatalysis and inspires the methodology on precise synthesis of catalytic materials.

Single-atom catalysts (SACs) with highly active sites atomically dispersed on substrates exhibit unique advantages regarding maximum atomic efficiency, abundant chemical structures, and extraordinary catalytic performances for multiple important reactions. In particular, M-N-C SACs (M=transition metal atom) demonstrate optimal electrocatalytic activity for the oxygen reduction reaction (ORR) and have attracted extensive attention recently. Despite substantial efforts in fabricating various M-N-C SACs, the principles for regulating the intrinsic electrocatalytic activity of their active sites have not been sufficiently studied. In this Review, we summarize the regulation strategies for promoting the intrinsic electrocatalytic ORR activity of M-N-C SACs by modulation of the center metal atoms, the coordinated atoms, the environmental atoms, and the guest groups. Theoretical calculations and experimental investigations are both included to afford a comprehensive understanding of the structure-performance relationship. Finally, future directions of developing advanced M-N-C SACs for electrocatalytic ORR and other analogous reactions are proposed.

Sustainable energy supply and sufficient chemical production are highly dependent on many essential catalytic processes for our sustainable society. On pursuing next‐generation catalysts, single‐atom catalysts (SACs) with high‐active sites atomically dispersed on substrates exhibit unique advantages regarding the maximum atomic efficiency, abundant chemical structures, and extraordinary catalytic performances for multiple vital reactions. In particular, M–N–C SACs (where M is a transition metal atom) demonstrate the optimal electrocatalytic activity for oxygen reduction reaction (ORR) and have attracted extensive attentions recently. Despite the substantial efforts on fabricating various M–N–C SACs, principles of regulating the intrinsic electrocatalytic activity of the M–N–C active sites are not yet sufficiently emphasized. In this review, regulation strategies of promoting the intrinsic electrocatalytic ORR activity of M–N–C SACs are summarized by modulating the center metal atoms, the coordinated atoms, the environmental atoms, and the guest groups, respectively. Theoretical calculations and experimental investigations are both included to afford comprehensive understandings on the structural‐performance relationship. Finally, future directions of developing advanced M–N–C SACs for electrocatalytic ORR and other analogous reactions are proposed.

Two new stilbenoids, stemobenoids A (1) and B (2), together with three known compounds were obtained from the roots of Stemona tuberosa. The structures of the new compounds were established by extensive spectroscopic analysis, including HRMS, 1D and 2D NMR data. Compounds 1 and 2 displayed potent quinone reductase inducing activity in Hepa 1c1c7 cells.

Single-atom catalysts (SACs) have great potential in electrocatalysis. Their performance can be rationally optimized by tailoring the metal atoms, adjacent coordinative dopants, and metal loading. However, doing so is still a great challenge because of the limited synthesis approach and insufficient understanding of the structure-property relationships. Herein, we report a new kind of Mo SAC with a unique O,S coordination and a high metal loading over 10 wt %. The isolation and local environment was identified by high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure. The SACs catalyze the oxygen reduction reaction (ORR) via a 2 e- pathway with a high H2 O2 selectivity of over 95 % in 0.10 m KOH. The critical role of the Mo single atoms and the coordination structure was revealed by both electrochemical tests and theoretical calculations.

Highly efficient electrocatalysts with high intrinsic activity for oxygen and sulfur redox reactions are strongly required for sustainable energy systems. Generally, cations serve as the real active sites in transition metal compound electrocatalysts, whose electrocatalytic activity is regulated by the surrounding anionic structure. Herein, an electrochemical reaction assisted by an anionic regulation strategy is proposed for precise construction of advanced electrocatalysts with extraordinary electrocatalytic activity. The electrochemical anionic regulation process ensures general release of the regulation reagents for precise substitution of sulfur anions in pristine hydroxide. The as-obtained hydroxysulfide electrocatalyst exhibits a desired electronic structure to afford superb electrocatalytic activity regarding reduced overpotential of 286 mV at 10 mA cm−2 for electrocatalytic oxygen evolution and improved polysulfide redox electrocatalytic activity. This contribution not only renders an emerging strategy for precise regulation of the anionic structure for improved electrocatalytic activity, but also provides information for the rational design of advanced electrocatalysts for sustainable energy applications.

Van der Waals heterostructures based on the two-dimensional (2D) semiconductor materials have attracted increasing attention due to their attractive properties. In this work, we demonstrate a high-sensitive back-gated phototransistor based on the vertical HfSe2/MoS2 heterostructure with a broad-spectral response from near-ultraviolet to near-infrared and an efficient gate tunability for photoresponse. Under bias, the phototransistor exhibits high responsivity of up to 1.42×103 A/W, and ultrahigh specific detectivity of up to 1.39×1015 cm⋅Hz1/2⋅W−1. Moreover, it can also operate under zero bias with remarkable responsivity of 10.2 A/W, relatively high specific detectivity of 1.43×1014 cm⋅Hz1/2⋅W−1, ultralow dark current of 1.22 fA, and high on/off ratio of above 105. These results should be attributed to the fact that the vertical HfSe2/MoS2 heterostructure not only improves the broadband photoresponse of the phototransistor but also greatly enhances its sensitivity. Therefore, the heterostructure provides a promising candidate for next generation high performance phototransistors.

Oxygen reduction reaction (ORR) constitutes the core process of many clean and sustainable energy systems including fuel cells and metal–air batteries. Developing high-performance and cost-efficiency ORR electrocatalysts is of great significance to the practical applications of the above-mentioned energy storage devices. Transition metal coordinated porphyrin electrocatalysts are highly considered as a promising substitution of noble-metal-based electrocatalyst because of their high ORR reactivity, where the ORR performances of the porphyrin-based electrocatalysts are highly dependent on the transition metal center. Herein a series of framework porphyrin electrocatalysts coordinated with different transition metal centers (M-POF, where M is Mn, Fe, Co, Ni, Cu, or Zn) was designed, synthesized, and evaluated in regards of electrocatalytic ORR performances. Among all, the Co-POF electrocatalyst exhibits the best ORR performances with the highest half-wave potential of 0.81 V vs. RHE and the lowest Tafel slope of 53 mV/dec. This contribution affords an optimized high-performance ORR electrocatalyst and provides instructions for further rational design of porphyrin-based ORR electrocatalysts for sustainable energy applications.

Efficient energy storage at low temperatures starves for competent battery techniques. Herein, inherent advantages of zinc-air batteries on low-temperature electrochemical energy storage are discovered. The electrode reactions are resistive against low temperatures to render feasible working zinc-air batteries under sub-zero temperatures. The relatively reduced ionic conductivity of electrolyte is identified as the main limiting factor, which can be addressed by employing a CsOH-based electrolyte through regulating the solvation structures. Accordingly, 500 cycles with a stable voltage gap of 0.8 V at 5.0 mA cm-2 is achieved at -10 °C. This work reveals the promising potential of zinc-air batteries for low-temperature electrochemical energy storage and inspires advanced battery systems under extreme working conditions.

The development of next‐generation high‐energy‐density batteries requires advanced electrode materials. Sulfurized polyacrylonitrile (SPAN) is considered a promising sulfur cathode with the merits of high specific capacity and long cycling stability for high‐performance lithium–sulfur (Li–S) batteries. Nevertheless, the practical performances of SPAN cathodes are severely limited by the unfavorable electron accessibility due to the relatively low intrinsic conductivity and large particle size. Herein, a redox mediation strategy is proposed to accelerate the electron transfer processes in working Li–S batteries with SPAN cathodes. Specifically, a quinone‐based redox mediator is introduced to provide an additional redox pathway with strengthened interfacial kinetics. The redox mediator assisted SPAN cathodes exhibit higher specific capacity, improved rate performance, reduced polarization, and longer cycling lifespan with both ether‐based and carbonate‐based electrolyte. This work demonstrates the feasibility of redox mediation to promote the electron accessibility for high‐performance Li–S batteries with SPAN cathodes.

Rechargeable zinc-air batteries constitute promising next-generation energy storage devices due to their intrinsic safety, low cost, and feasibility to realize high cycling current density and long cycling lifespan. Nevertheless, their cathodic reactions involving oxygen reduction and oxygen evolution are highly sluggish in kinetics, requiring high-performance noble-metal-free bifunctional electrocatalysts that exceed the current noble-metal-based benchmarks. Herein, a noble-metal-free bifunctional electrocatalyst is fabricated, which demonstrates ultrahigh bifunctional activity and renders excellent performance in rechargeable zinc-air batteries. Concretely, atomic Co-N-C and NiFe layered double hydroxides (LDHs) are respectively selected as oxygen reduction and evolution active sites and are further rationally integrated to afford the resultant CoNC@LDH composite electrocatalyst. The CoNC@LDH electrocatalyst exhibits remarkable bifunctional activity delivering an indicator ΔE of 0.63 V, far exceeding the noble-metal-based Pt/C+Ir/C benchmark (ΔE = 0.77 V) and most reported electrocatalysts. Correspondingly, ultralong lifespan (over 3600 cycles at 10 mA cm-2 ) and excellent rate performances (cycling current density at 100 mA cm-2 ) are achieved in rechargeable zinc-air batteries. This work highlights the current advances of bifunctional oxygen electrocatalysis and endows high-rate and long-cycling rechargeable zinc-air batteries for efficient sustainable energy storage.

Two new stilbenoids, stemobenoids A (

Quinoa is known for its rich nutrients and bioactive compounds. In order to elucidate the preliminary structural characteristics and biological activity of polysaccharides from quinoa (QPs), five crude polysaccharides (QPE50, QPE60, QPE70, QPE80 and QPE90) were successively fractionated by gradient ethanol, and their physicochemical properties, antioxidant and antidiabetic activities were analyzed. The results implied that their total sugar contents were 52.82%, 63.69%, 67.15%, 44.56%, and 41.01%, and their weight-average molecular weights were 13,785 Da, 6489 Da, 4732 Da, 3318 Da, and 1960 Da, respectively. Glucose was a predominantly monosaccharide in these QPs, which together in QPE50, QPE60, QPE70, QPE80, and QPE90, respectively, made up 94.37%, 87.92%, 92.21%, 100%, and 100% of the total polysaccharide. Congo red test showed that all five QPs contained triple-helix structure. The Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffractometry (XRD) results suggest that the QPs form a semi-crystalline polymer constituted typical functional groups of polysaccharide including CO, CH and OH. The thermogravimetric analysis (TGA) of QPs showed that weight loss was at about 200 &deg, C and 320 &deg, C. The observation from scanning electron microscope (SEM) and atomic force microscope (AFM) image indicated that the morphology of QPs exhibited spherical shape. Antioxidant and antidiabetic assay exhibited that all five QPs samples had certain antioxidant and antidiabetic activities, and QPE90 showed the best antioxidant and antidiabetic activity. Overall, QPs present a promising natural source of food antioxidants and antidiabetic agents.

e-Poly-l-lysine (e-PL) consists of 25-35 lysine residues which are linked by an isopeptide bond formed by dehydration condensation of α-carboxyl and e-amino groups and has good antibacterial activity and broad-spectrum inhibition range. However, there is no clear conclusion about the structure and antibacterial mechanism of e-PL in aqueous solution. Herein, a high purity of e-PL was prepared using Amberlite IRC-50 ion-exchange resin. Membrane filtration and dynamic light scattering were used to study the variations of e-PL aggregation in aqueous solution with pH value. The conformational changes and antibacterial activities of e-PL and carbamoylated e-PL in different water environments were studied with circular dichroism (CD) and inhibition zone. The structural changes during the spray-drying process were determined by Fourier transform infrared spectroscopy. The results indicated that the side chain amino charge played a decisive role in the e-PL conformation and aggregation. e-PL exhibited the properties of a β-sheet during spray drying from acidic liquids to solids. The cation enhanced the antibacterial activity of e-PL but did not play a key role. Instead, the backbone of e-PL might determine the mechanism of e-PL antibacterial.

Rechargeable zinc-air batteries afford great potential toward next-generation sustainable energy storage. Nevertheless, the oxygen redox reactions at the air cathode are highly sluggish in kinetics to induce poor energy efficiency and limited cycling lifespan. Air cathodes with asymmetric configurations significantly promote the electrocatalytic efficiency of the loaded electrocatalysts, whereas rational synthetic methodology to effectively fabricate asymmetric air cathodes remains insufficient. Herein, a strategy of asymmetric interface preconstruction is proposed to fabricate asymmetric air cathodes for high-performance rechargeable zinc-air batteries. Concretely, the asymmetric interface is preconstructed by introducing immiscible organic-water diphases within the air cathode, at which the electrocatalysts are in situ formed to achieve an asymmetric configuration. The as-fabricated asymmetric air cathodes realize high working rates of 50 mA cm

The rechargeable zinc-air battery (ZAB) is a promising energy storage technology owing to its high energy density and safe aqueous electrolyte, but there is a significant performance bottleneck. Generally, cathode reactions only occur at multiphase interfaces, where the electrocatalytic active sites can participate in redox reactions effectively. In the conventional air cathode, the 2D multiphase interface on the surface of the gas diffusion layer (GDL) inevitably results in an insufficient amount of active sites and poor interfacial contact, leading to sluggish reaction kinetics. To address this problem, a 3D multiphase interface strategy is proposed to extend the reactive interface into the interior of the GDL. Based on this concept, an asymmetric air cathode is designed to increase the accessible active sites, accelerate mass transfer, and generate a dynamically stabilized reactive interface. With a NiFe layered-double-hydroxide electrocatalyst, ZABs based on the asymmetric cathode deliver a small charge/discharge voltage gap (0.81 V at 5.0 mA cm-2 ), a high power density, and a stable cyclability (over 2000 cycles). This 3D reactive interface strategy provides a feasible method for enhancing the air cathode kinetics and further enlightens electrode designs for energy devices involving multiphase electrochemical reactions.

Lithium–sulfur (Li–S) batteries are highly considered for next‐generation energy storage due to their ultrahigh theoretical energy density of 2600 Wh kg−1. The conversion reactions between lithium polysulfides (LiPSs) constitute the core process in working Li–S batteries. Electrochemical impedance spectroscopy (EIS) analysis of LiPS symmetric cells is an effective tool to provide detailed information on the LiPS conversion reactions and direct further kinetic promotion. However, reasonable interpretation of the EIS responses is so far insufficiently addressed without a well‐defined equivalent circuit. Herein, a systematic analysis on the EIS responses of LiPS symmetric cells is conducted to provide a comprehensible equivalent circuit. Interfacial contact, surface reaction, and diffusion are decoupled according to their respective characteristic frequency using the distribution of relaxation time analysis method. A well‐defined equivalent circuit is proposed to accurately fit the experimental EIS responses, unambiguously interpret key parameters, and be feasible with a wide range of experimental conditions. This work presents the methodology of understanding the EIS responses of LiPS symmetric cells and inspires analogous analysis on vital electrochemical processes.

e-poly- l -lysine (e-PL) is a novel biopreservative with wide antibacterial spectrum, high safety, and stable property. However, the color of e-PL generating from manufacturing process lowers its appearance and limits its application. This work aimed to decolorize e-PL by hydrogen peroxide. Impacts of hydrogen peroxide concentration, pH, duration time and temperature were discussed. Physicochemical property and bioactivity of e-PL were explored. Results indicated that 43.2 % color saturation and 94.54 % recovery rate were reached when the concentration of hydrogen peroxide, pH, duration time and temperature were 3.0 %, 7.0, 1.5 h and 70℃ respectively. Furthermore, the MIC (minimal inhibitory concentration) of the hydrogen peroxide treated e-PL for Bacillus subtilis, Escherichia coli, and Staphylococcus aureus were 2 mg/mL, 0.1 mg/mL, and 0.1 mg/mL respectively, which was similar with untreated e-PL. At last, cytotoxicity test indicated that no cytotoxicity could be observed at concentration lower than 2 mg/mL e-PL. As a result, hydrogen peroxide treatment on e-PL could significantly decolorize e-PL without impairing the antibacterial performance and changing the cytotoxicity. Hydrogen peroxide treatment is a promising method to improve the appearance of products, to reduce the cost of decoloration, and to enlarge the application in food and cosmetics industry.

A new magnetic Fe₃O₄@C@Ag₃PO₄ nanocomposites photocatalyst with visible light response has been prepared by solvothermal, hydrothermal and precipitation process. The photocatalyst exhibited high photocatalytic activity and stability for the degradation of rhodamine B (RhB). Almost 100% of RhB was photodegraded with the assistance of magnetic Fe₃O₄@C@Ag₃PO₄ nanocomposites after 40 min, and the photocatalyst showed no obvious loss of photocatalytic activity after four times of cyclic utilization. Furthermore, the magnetic Fe₃O₄@C@Ag₃PO₄ nanocomposites can be separated by external magnetic field. Further study proved that the photogenerated holes were the main active species in the degradation process.

Rechargeable zinc-air batteries are considered as next-generation energy storage devices because of their ultrahigh theoretical energy density of 1086 Wh kg-1 (including oxygen) and inherent safety originating from the use of aqueous electrolyte. However, the cathode processes regarding oxygen reduction and evolution are sluggish in terms of kinetics, which severely limit the practical battery performances. Developing high-performance bifunctional oxygen electrocatalysts is of great significance, yet to achieve better bifunctional electrocatalytic reactivity beyond the state-of-the-art noble-metal-based electrocatalysts remains a great challenge. Herein, a composite Co3 O4 @POF (POF=framework porphyrin) bifunctional oxygen electrocatalyst is proposed to construct advanced air cathodes for high-performance rechargeable zinc-air batteries. The as-obtained composite Co3 O4 @POF electrocatalyst exhibits a bifunctional electrocatalytic reactivity of ΔE=0.74 V, which is better than the noble-metal-based Pt/C+Ir/C electrocatalyst and most of the reported bifunctional ORR/OER electrocatalysts. When applied in rechargeable zinc-air batteries, the Co3 O4 @POF cathode exhibits a reduced discharge-charge voltage gap of 1.0 V at 5.0 mA cm-2 , high power density of 222.2 mW cm-2 , and impressive cycling stability for more than 2000 cycles at 5.0 mA cm-2 .

A new model is proposed for the optimal scheduling of gas-electric integrated energy systems, considering the incentive demand response (IBDR) to provide the reserve ancillary service. By incorporating the IBDR, one hand, the system can give full play to the complementary functions of different energy sources to enhance the efficiency of the system; on the other hand, more flexibility can be utilized to cope with the uncertainty of wind power with IBDR providing reserves with conventional units simultaneously. We establish the IBDR model with segmental price-quantity curves, and the transient gas flow and steady state power flow are combined to formulate the operation model of gas-electric integrated systems. A 6-node power network and a 12-node natural gas network were selected to construct a gas-electric integrated energy system. The simulation results show that the IBDR can improve the flexibility of the system and decrease the total operation cost of the gas-electric integrated energy system.