Customizing pyridinic nitrogen coordination in Ni-N-C for electrocatalytic CO2reduction towards CO.

Nickel anchored N-doped carbon electrocatalysts (Ni-N-C) are rapidly developed for the electrochemical reduction reaction of carbon dioxide (CO2RR). However, the high-performanced Ni-N-C analogues design for CO2RR remains bewilderment, for the reason lacking of definite guidance for its structure-activity relationship. Herein, the correlation between the proportion of nitrogen species derived from various nitrogen sources and the CO2RR activity of Ni-N-C is investigated. The X-ray photoelectron spectroscopy (XPS) spectrum combined with the CO2RR performance results show that pyridinic-N content has a positive correlation with CO2RR activity. Moreover, density functional theory (DFT) demonstrates that pyridinic-N coordinated Ni-N4 sites offers optimized free energy and favorable selectivity towards CO2RR compared with pyrrolic-N. Accordingly, Ni-Na-C with highest pyridinic-N content (ammonia as nitrogen source) performs superior CO2RR activity, with the maximum carbon monoxide faradaic efficiency (FECO) of 99.8% at -0.88 V vs. RHE and the FECO surpassing 95% within potential ranging of -0.88 to -1.38 V vs. RHE. The building of this parameter for CO2RR activity of Ni-N-C give instructive forecast for low-cost and highly active CO2RR electrocatalysts. .

Three-dimensional ordered macroporous design of heterogeneous cobalt-iron phosphides as oxygen evolution electrocatalyst.

Oxygen evolution reaction (OER) plays a key role in electrochemical conversion, which needs efficient and economical electrocatalyst to boost its kinetics for large-scale application. Herein, a bimetallic CoP/FeP2heterostructure with a three-dimensional ordered macroporous structure (3DOM-CoP/FeP2) was synthesized as an OER catalyst to demonstrate a heterogeneous engineering induction strategy. By adjusting the electron distribution and producing a lot of active sites, the heterogeneous interface enhances catalytic performance. High specific surface area is provided by the 3DOM structure. Additionally, at the solid-gas-electrolyte threephase interface, the electrocatalytic reaction exhibits good mass transfer.In situRaman spectroscopy characterization revealed that FeOOH and CoOOH reconstructed from CoP/FeP2were the true OER active sites. Consequently, the 3DOM-CoP/FeP2demonstrates superior OER activity with a low overpotentials of 300/420 mV at 10/100 mA cm-2and meritorious OER durability. It also reveals promising performance as the overall water splitting anode.

Neuroprotective effect of marrubiin against MPTP-induced experimental Parkinson's disease in male wistar rats.

In this work, we have analyzed the neuroprotective activity of marrubiin against MPTP-induced Parkinson's disease (PD) in rat brains. MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) a neurotoxin was administered intraperitoneally (i.p.,) to rats and then treated using marrubiin. After marrubiin treatment, rats were trained, and tested for behavioral analyses like cognitive performance, open field test, rotarod test, grip strength test, beam walking test, the status of body weight, and striatal levels of neurotransmitters like dopamine, norepinephrine, serotonin, DOPAC, homovanillic acid, 5-hydroxy indole acetic acid, the status of oxidative stress markers like LPO, protein carbonyl content (PCC), Xanthine oxidase (XO), and status of antioxidant enzyme levels like SOD, CAT, GPX in the striatum and hippocampal tissues, status of neuroinflammatory markers like TNF-α, IL1ß, IL-6, and status of histological architecture in brain striatum were also analyzed. All these parameters were significantly (p < 0.05) abnormal in MPTP-induced rats. Marrubiin (MB) treated shows significant (p < 0.05) near normal behavioral restoration in cognitive performance, open field, rotarod, grip strength, and beam walking tests. Furthermore, the status of body weight, and levels of neurotransmitters, were also significantly (p < 0.05) reversed to near normalcy in marrubiin-treated rats. Similarly, oxidative stress, antioxidant enzyme levels in the striatum and hippocampal tissues, TNF-α, IL1ß, IL-6 levels, and histological architecture were noted to be restored to near normalcy in marrubiin-treated rats. Collectively, our preliminary results highlight the neuroprotective ability of marrubiin. However, the cellular and biochemical mechanisms of marrubiin's neuroprotective ability have to be studied in detail.

Protective Cerium Oxide Coating Promoted Ce-Doping and Reconstruction of High-Valence NiFe Sulfide toward Robust Overall Water Splitting.

Active and stable electrocatalysts toward oxygen evolution reaction (OER) are essential for alkaline water splitting. Herein, an efficient and durable high-valence NiFe-based OER electrocatalyst is developed, featuring a protective CeO2- x coating to prevent the corrosion of carbon substrates during oxidative OER operation, ensuring excellent catalyst stability. The incorporation of a CeO2- x coating also leads to the formation of a Ce-doped NiFe sulfide catalyst. The Ce modulator enables the dynamic transformation of NiFe sulfide into highly active (oxy)hydroxide species with high-valence Ni sites and enhanced Ni─O covalency, thereby improving its OER catalytic activity. Accordingly, the prepared NiFeS2 /CeO2- x /CC catalyst achieves enhanced OER activity with an overpotential of 260 mV at 100 mA cm-2 in 1.0 m KOH. Moreover, the catalyst achieves 100 mA cm-2 current density at an overpotential of 187 mV for the hydrogen evolution reaction. The anion exchange membrane water electrolyzer reached 500 mA cm-2 at 1.73 V cell voltage with excellent stability for 500 h continuous operation. This study demonstrates a promising approach for the fabrication of robust water-splitting electrocatalysts.

Manipulating Redox Kinetics using p-n Heterojunction Biservice Matrix as both Cathode Sulfur Immobilizer and Anode Lithium Stabilizer for Practical Lithium-Sulfur Batteries.

As an attractive high-energy-density technology, the practical application of lithium-sulfur (Li-S) batteries is severely limited by the notorious dissolution and shuttle effect of lithium polysulfides (LiPS), resulting in sluggish reaction kinetics and uncontrollable dendritic Li growth. Herein, a p-n typed heterostructure consisting of n-type MoS2 nanoflowers embedded with p-type NiO nanoparticles is designed on carbon nanofibers (denoted as NiO-MoS2 @CNFs) as both cathode sulfur immobilizer and anode Li stabilizer for practical Li-S batteries. Such p-n typed heterostructure is proposed to establish the built-in electric field across the heterointerface for facilitated the positive charge to reach the surface of NiO-MoS2 , meanwhile inherits the excellent LiPS adsorption ability of p-type NiO nanoparticles and catalytic ability of n-type MoS2 . As the anode matrix, the implementation of NiO-MoS2 heterostructure can prevent the growth of Li dendrites by enhancing the lithiophilicity and reducing local current density. The obtained Li-S full battery exhibits an ultra-high areal capacity over 7.3 mAh cm-2 , far exceeding that of current commercial Li-ion batteries. Meanwhile, a stable cycling performance can be achieved under low electrolyte/sulfur ratio of 5.8 µL mg-1 and negative/positive capacity ratio of 1. The corresponding pouch cell maintains high energy density of 305 Wh kg-1 and stable cycling performance under various bending angles.

Nanoflower-like FeVNi3S2-xas efficient electrocatalyst for alkaline oxygen evolution reaction.

The development of low cost efficient catalysts for oxygen evolution reaction (OER) is still a obstacle to realize the commercialization of electrocatalytic water splitting. Herein, interface engineering and heteroatom doping is adopted to synthesize iron and vanadium doped nickel sulfide on nickel foam via hydrothermal method followed by hydrogen treatment to create sulfur defects. The optimized nanoflower-like FeVNi3S2-x/NF is an efficient OER electrocatalyst that outperforms many of the reported transition metals catalysts. Benefiting from abundant sulfur defects and the synergistic effect of heteroatom doping, FeVNi3S2-x/NF exhibits an ultralow overpotential of 230 mV to reach a current density of 100 mA cm-2, a rapid reaction kinetics with a small Tafel slope of 46.6 mV dec-1, and a stable long-term durability in 1 M KOH. Experimental results and characterizations confirm that sulfur vacancies together with the synergistic effect from multiple heteroatom doping can effectively regulate the electronic structure, resulting in increased electrical conductivity and electrochemically active surface area, thus enhancing OER performance. Furthermore,in situRaman spectroscopy reveals that, the reconstitution amorphous nickel oxyhydroxide (NiOOH) on the catalyst surface is responsible for catalyzing the OER reaction. This work represents a promising methodology to synthesize low-cost and highly active OER electrocatalysts.

Bismuth Gadolinium Oxychloride with a Remarkable Visible-Light-Responsive O2 Evolution Activity Promoted by Iodine Doping.

Visible-light-responsive bismuth-based oxyhalide has recently attracted extensive attention, however, the promotion of its charge separation is still challenging. Herein, we introduce iodine into Bi2 GdO4 Cl to synthetize I-doped Bi2 GdO4 Cl (denoted as yI-Bi2 GdO4 Cl, 0≤y≤2). The incorporation of I- ions is found to enhance light absorption and to accelerate charge separation by combining various characterizations such as density functional theory calculation, photoelectrochemical test, electrochemical impedance spectroscopy, photoluminescence spectrum, and open-circuit voltage decay. The O2 -evolving performances of 1I-Bi2 GdO4 Cl with optimized dopant concentration of I- ion and IrO2 loaded 1I-Bi2 GdO4 Cl are tremendously enhanced by ca. 4 and 45 times compared to pristine Bi2 GdO4 Cl. Notably, The O2 evolution rate reaches as high as 154.8 µmol ⋅ h-1 with an apparent quantum efficiency of ∼1.1 % at 420 nm. The synthetic iodine-doped photocatalyst remains stable after long-term photoreaction, demonstrating its potential in the field of photocatalysis.

Constructing MIL-101(Cr) membranes on carbon nanotube films as ion-selective interlayers for lithium-sulfur batteries.

It is of significant importance to suppress the polysulfide shuttle effect for the commercial application of lithium-sulfur batteries. Herein, continuous MIL-101(Cr) membranes were successfully fabricated on carbon nanotube films utilizing a simplein situgrowth method, aiming at constructing interlayer materials for inhibiting the shuttle effect. Owing to the suitable pore aperture and super electrolyte wettability, the as-developed MIL-101(Cr) membrane can effectively inhibit the shuttle behaviour of polysulfides while allowing the fast transport of Li-ions simultaneously, working as an ionic sieve. Additionally, this MOFs membrane is also helpful in accelerating the polysulfide catalytic conversion. Therefore, the proposed interlayer delivers an extraordinary rate capability, showing a remarkable capacity of 661.9 mAh g-1under 5 C. Meanwhile, it also exhibits a high initial capacity of 816.1 mAh g-1at 1 C and an exceptional durability with an extremely low capacity fading of 0.046% per cycle over 500 cycles.

Constructing MIL-101(Cr) membranes on carbon nanotube films as ion-selective interlayers for lithium-sulfur batteries.

It is of significant importance to suppress the polysulfide shuttle effect for the commercial application of lithium-sulfur batteries. Herein, continuous MIL-101(Cr) membranes were successfully fabricated on carbon nanotube films utilizing a simple in-situ growth method, aiming at constructing interlayer materials for inhibiting the shuttle effect. Owing to the suitable pore aperture and super electrolyte wettability, the as-developed MIL-101(Cr) membrane can effectively inhibit the shuttle behaviour of polysulfides while allowing the fast transport of Li-ions simultaneously, working as an ionic sieve. Additionally, this MOFs membrane is also helpful in accelerating the polysulfide catalytic conversion. Therefore, the proposed interlayer delivers an extraordinary rate capability, showing a remarkable capacity of 661.9 mAh g-1 under 5 C. Meanwhile, it also exhibits a high initial capacity of 816.1 mAh g-1 at 1 C and an exceptional durability with an extremely low capacity fading of 0.046 % per cycle over 500 cycles.

A sulfur defective Mn-doped Ni3S2-xnanosheet for enhanced overall water splitting.

Non-precious and stable electrocatalysts towards both oxygen and hydrogen evolution reaction (OER/HER) are essential for effective overall water splitting in alkaline solution. In this study, a sulfur defective and manganese-doped nickel sulfide nanosheet that uniformly grown on nickel foam substrate (Mn-Ni3S2-x@NF) is synthesized. In alkaline solution, the Mn-Ni3S2-x@NF showed a low overpotential of 76 and 110 mV for OER and HER at 10 mA cm-2, respectively, together exhibiting excellent stability for both OER and HER reaction. It was confirmed by the experimental results that sulfur defects and Mn-doping synergistically optimized the electronic structure of Mn-Ni3S2-xwith increased electrical conductivity and enhanced OER/HER activity. Moreover, amorphous nickel oxyhydroxide (NiOOH) was observed byin situRaman during the OER condition, suggesting NiOOH is the active phase for OER reaction. Furthermore, the electrolyzer assembled by Mn-Ni3S2-x@NF merely needs 1.46 V to reach 10 mA cm-2and shows good stability as well. This study provides a feasible way to prepare high-efficiency bifunctional catalysts for overall water splitting.

Coordinated Co-NC/CoFe dual active centre embedded three-dimensional ordered macroporous framework as bifunctional catalyst for efficient and stable zinc-air batteries.

Developing efficient and stable multifunctional electrocatalyst is very important for zinc-air batteries in practical. Herein, semiconductive spinel CuFe2O4supported Co-N co-doped carbon (Co-NC) and CoFe alloy nanoparticles were proposed. In this strategy, the three-dimensional ordered macroporous CuFe2O4support provides rich channels for mass transmission, revealling good corrosion-resistance and durability at the same time. ZIF-67 derived Co-NC decoration improves the conductivity of the catalyst. Further, the uniformly distributed Co-NC and CoFe nanoparticles (C/CF) dramatically promote the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance. Accordingly, C/CF@CuFe2O4catalyst shows remarkable bifunctional electrocatalytic activity, with an ORR half-wave potential of 0.86 V, and an OER over-potential of 0.46 V at 10 mA cm-2. The zinc-air battery using this catalyst exhibits a power density of 95.5 mW cm-2and a durable cyclability for over 170 h at a current density of 10 mA cm-2, which implies a great potential in practical application.

Design and Fabrication of Hierarchical NiCoP-MOF Heterostructure with Enhanced Pseudocapacitive Properties.

Metal-organic framework (MOF)-derived heterostructures possessing the merits of each component are thought to display the enhanced energy storage performance due to their synergistic effect. Herein, a functional heterostructure (NiCoP-MOF) composed of nickel/cobalt-MOF (NiCo-MOF) and phosphide (NiCoP) is designed and fabricated via the localized phosphorization of unusual lamellar brick-stacked NiCo-MOF assemblies obtained by a hydrothermal method. The experimental and computational analyses reveal that such-fabricated heterostructures possess the modulated electronic structure, abundant active sites, and hybrid crystalline feature, which is kinetically beneficial for fast electron/ion transport to enhance the charge storage capability. Examined as the supercapacitor electrode, the obtained NiCoP-MOF compared to the NiCo-MOF delivers a high capacity of 728 C g-1 (1.82 C cm-2 ) at 1 A g-1 with a high capacity retention of 430 C g-1 (1.08 C cm-2 ) when increasing the current density to 20 A g-1 . Importantly, the assembled solid-state NiCoP-MOF-based hybrid supercapacitor displays superior properties regarding the capacity (226.3 C g-1 ), energy density (50.3 Wh kg-1 ), and durability (≈100% capacity retention over 10 000 cycles). This in situ heterogenization approach sheds light on the electronic structure modulation while maintaining the well-defined porosity and morphology, holding promise for designing MOF-based derivatives for high performance energy storage devices.

A multifunctional UiO-66@carbon interlayer as an efficacious suppressor of polysulfide shuttling for lithium-sulfur batteries.

Restraining the shuttle effect in lithium-sulfur (Li-S) battery is crucial to realize its practical application. In this work, a UiO-66@carbon (UiO-66@CC) interlayer was developed for Li-S battery by growing a continuous UiO-66 film on carbon cloth. The continuous UiO-66 crystal layer contributes to provide sufficient adsorptive and catalytic sites for efficient adsorption and catalytic conversion towards polysulfides. Moreover, the hydrophilic property of UiO-66 material ensures the full infiltration of electrolyte and accelerates the transportation of lithium ions. Profiting from the above advantages of the proposed interlayer, the shuttle effect is effectively inhibited and a fast redox kinetic is also realized. Accordingly, the Li-S battery using UiO-66@CC delivers a specific capacity of 1228.9 mAh g-1at 0.2 C with a nearly 100% capacity retention after 100 cycles, and the first specific capacity is 1033.1 mAh g-1at 1.0 C with a decay rate of 0.07% over 600 cycles. Meanwhile, UiO-66@CC interlayer also has an excellent rate performance with a specific capacity of 535.9 mAh g-1at 5.0 C and a high area capacity of 6.2 mAh cm-2at increased sulfur loading (8.15 mg cm-2).

A conductive and ordered macroporous structure design of titanium oxide-based catalytic cathode for lithium-sulfur batteries.

The application of lithium-sulfur (Li-S) batteries is hindered by the insulating characteristic of sulfur and slow reaction kinetics of lithium polysulfides. Here, we propose a three-dimensionally ordered macroporous (3DOM) structured conductive polar Ta-doped TiO2framework with supported Co active site (CoTa@TiO2) to enhance the conversion kinetics of polysulfides. The 3DOM structure serves as an efficient sulfur host for the active sulfur through abundant pores and adsorption site. At the same time, the macropores can buffer the volume expansion of sulfur and enlarged mass transfer. The strong electrostatic attraction between Ti-O bond and polysulfide also promotes the adsorption of polysulfides. Moreover, the doped-Ta improves the conductivity of TiO2by narrowing the band gap, whereas the supported Co can accelerate the catalytic transformation. Benefited from advanced structural design and synergistic effect of Co and Ta doped TiO2,the Li-S cell with 3DOM CoTa@TiO2cathode exhibits an impressive areal capacity of 3.4 mAh cm-2under a high sulfur loading of 5.1 mg cm-2. This work provides an alternative strategy for the development of carbon-based cathode materials for Li-S batteries.

Nanoscale melamine-based porous organic frameworks as host material for efficient polysulfides chemisorption in lithium-sulfur batteries.

In order to improve the electrochemical capacity of lithium-sulfur batteries (LiSBs), it is necessary to introduce the porous organic frameworks with well-defined hetero atom species in cathode. In this work, porous nanomaterials with ultra-high nitrogen containing and adjustable porosity named Schiff-based networks (SNWs) were selected as potential candidate for sulfur host in LiSBs. Two SNW samples have been constructed by reacting melamine with phenyl or biphenyl dialdehydes through microwave-assisted method, respectively. The high BET surface area provided sufficient room to impregnate sulfur and mitigated volume changes during the cycling performance. Besides, the high density and homogeneous distribution of pyridinic-N and aminic-N in SNW nanoparticles can cooperatively form lithium polysulfides (LiPSs) chemisorption via enhanced Li+-N interactions to effectively suppressed the 'shuttle effect'. Attributed to its structural superiorities, SNW/S cathode demonstrates excellent electrochemical performance in LiSBs. In particular, SNW-2/S cathode delivers an excellent cyclability with a specific capacity of 620 mAh · g-1 after 500 cycles at 0.5 C, counting with a low capacity fading of 0.0508% per cycle. This work highlights the importance of rational design for effective LiPSs chemisorption and pioneers a facile strategy for developing suitable sulfur host materials towards high-performance LiSBs.

Two-dimensional Co(OH)2/graphene oxide composite as an efficient multifunctional interlayer for high-performance lithium-sulfur batteries.

The shuttling-effect of soluble lithium-based polysulfides (LiPS) represents one of the main obstacles for practical application of lithium-sulfur (Li-S) batteries. Herein, to address this issue, a flexible Li-S interlayer consisting of a two-dimensional α-Co(OH)2 nano-plate and graphene oxide (GO) is developed using a simple vacuum filtration technique. In the interlayer, the α-Co(OH)2 and GO are assembled into a layered structure forming a physical barrier for the shuttling of LiPS. Additionally, the α-Co(OH)2 offers strong chemical adsorption and efficient catalysis performance towards LiPS conversion, further inhibiting its shuttling. Attributed to these beneficial features of the interlayer, the Li-S battery delivers an initial discharge capacity of 834 mAh g-1 at the current density of 1 C. More importantly, after 300 cycles, a high discharge capacity of 590 mAh g-1 was retained, corresponding to a low capacity fading rate of 0.1% per cycle. This work might be of great interest for the feasible and scalable preparation of multifunctional interlayers in Li-S batteries.

Synthesis of microflower-like vacancy defective copper sulfide/reduced graphene oxide composites for highly efficient lithium-ion batteries.

Copper sulfide (CuS) is considered a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and good electrical conductivity. However, the inferior cycle performance and low coulombic efficiency of CuS caused by structure detoriation and degradation and the 'shuttling effect' of polysulfide intermediates are restricting its practical application. In this work, we report a facile method to generate S vacancies (Vs) in CuS nanoflowers by thermal annealing in Ar. The obtained CuS was composited with reduced graphene oxide (rGO) to prepare an anode for LIBs. The existence of vacancy defects in CuS leads to electron delocalization and excitation, which is responsible for the conductivity improvement and fast charge transport kinetics. Meanwhile, the graphene coating layer ensures fast pathways for Li+ ion diffusion and provides strong physical adsorption of the polysulfides. Furthermore, hierarchical CuS spheres composed of ultrathin nanosheets provide large void spaces to accommodate the volume expansion of CuS. The synthesized composite exhibited a high initial discharge capacity of 882 mAh g-1 and demonstrated stable cyclability along with around 99% coulombic efficiency over 100 cycles. The results of this work reveal that Vs-CuS/rGO composites are promising anodes to enhance the performance of next-generation lithium-ion batteries.

Thermal Decomposition Mechanism and Fire-Extinguishing Performance of trans-1,1,1,4,4,4-Hexafluoro-2-butene: A Potential Candidate for Halon Substitutes.

In view of the appropriate physicochemical characteristics and environmental friendliness of the trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(E)) substance, the thermal-decomposition mechanism as well as the fire-extinguishing mechanism and performance of this agent were systematically studied by employing both experimental and theoretical methods in this work. We found that the HFO-1336mzz(E) agent not only has promising thermal stability at room temperature but also exhibits pronounced fire-extinguishing performance, which is comparable to that of HFC-236fa and even better than that of HFC-125 extinguishant. Additionally, the promising fire-extinguishing performance of HFO-1336mzz(E) may result from the physical and chemical extinguishing effect of its thermal-decomposition products including HFO-1336mzz(Z), HC≡CCF3, CF3C≡CCF3, and CF3H, which makes a significant contribution to capturing the free radicals in the flame, as well as cooling and diluting the combustible fuel-air mixture. Both experimental and theoretical results suggest that the HFO-1336mzz(E) agent is a highly recommendable candidate for Halon extinguishant, which is worthy of further investigation and evaluation of its practical applicability in fire-suppression utilization.

Surface-engineered cobalt nitride composite as efficient bifunctional oxygen electrocatalyst.

Efficient and low-cost bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for the practical application of rechargeable metal-air batteries. In this work, we developed an efficient cobalt nitride hybrid bifunctional electrocatalyst, which consists of sulfur-doped and mildly oxidized Co5.47N nanoparticles supported on nitrogen-doped reduced graphene oxide sheet (O-S-Co5.47N@N-RGO). The composite exhibits good ORR-OER catalytic activity and excellent stability as well. It delivers an ORR half-wave potential of 0.82 V and an over-potential of 380 mV for OER at 10 mA cm-2 in 0.1 M KOH electrolyte. Density functional theory calculations indicate that the ORR activity of the composite might have originated from the Co-N4 site in the RGO sheet, whereas the surface Co sites on O-S-Co5.47N crystal are responsible for its OER activity. The facile preparation method and insight into the ORR-OER active sites reported in this study advances the development of high-performance bifunctional oxygen electrocatalyst.

Pomegranate-Inspired Design of Highly Active and Durable Bifunctional Electrocatalysts for Rechargeable Metal-Air Batteries.

Rational design of highly active and durable electrocatalysts for oxygen reactions is critical for rechargeable metal-air batteries. Herein, we report the design and development of composite electrocatalysts based on transition metal oxide nanocrystals embedded in a nitrogen-doped, partially graphitized carbon framework. Benefiting from the unique pomegranate-like architecture, the composite catalysts possess abundant active sites, strong synergetic coupling, enhanced electron transfer, and high efficiencies in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The Co3O4-based composite electrocatalyst exhibited a high half-wave potential of 0.842 V for ORR, and a low overpotential of only 450 mV at the current density of 10 mA cm(-2) for OER. A single-cell zinc-air battery was also fabricated with superior durability, holding great promise in the practical implementation of rechargeable metal-air batteries.