Oxygen Reduction Reaction Catalysis Research Articles

Sn Nanoclusters Confined in COP‐Derived Carbon for Catalytic Oxygen Reduction Reaction

AbstractThe development of catalysts composed of single atoms is crucial for enhancing the performance of oxygen reduction reaction (ORR). However, the unsatisfactory intrinsic activity of these catalysts still poses a major challenge, limiting their overall effectiveness. One approach to addressing this challenge is the introduction of metal clusters, which can form a synergistic effect with the single atoms, ultimately improving their performance. In this study, core‐shell structured carbon polymer is constructed with Zn atoms and Sn nanoclusters by directly subjecting pyrolysis of the covalent organic polymer (COP) and metal organic framework (MOF) (COP@MOF). The thin COP shell serves a dual purpose: it prevents the collapse and aggregation of zeolitic imidazolate framework‐8 (ZIF‐8) and promotes the formation of mesopores, facilitating mass transport and enhancing the graphitization degree to improve conductivity. The resulting Sn‐COP@MOF800 exhibits promising catalytic performance in the ORR, demonstrating a half‐wave potential of 0.81 V and current density of 5.56 mA cm−2 in 0.1 m KOH, which is comparable to that of Pt/C. This study provides new ideas for exploring the application of metal single atoms and metal nanoclusters in ORR catalysis through synergistic effects.

The synergistic anti‐corrosion performance and mechanism of meso‐tetra(4‐carboxyphenyl)porphine on steel bars in alkaline environments

AbstractCorrosion protection of steel bars in alkaline concrete environments poses a common challenge in marine engineering. One approach to mitigate steel bar corrosion is the addition of corrosion inhibitors to the concrete. In alkaline environments, the passivation of rebars occurs through anodic passivation coupled with the cathodic oxygen reduction reaction (ORR). The catalysis of ORR can expedite anode passivation. To investigate the corrosion inhibition of steel bars in alkaline environments, meso‐tetra(4‐carboxyphenyl)porphine (TCPP), known for its ORR catalytic properties, is selected. TCPP forms adsorption films on the surface of steel bars, facilitating the formation of passivation films. TCPP primarily adsorbs onto active sites on the surface of the passivation film, where lattice iron ions have leached. The adsorbed TCPP accelerates the formation of the passivation film through ORR catalysis, inhibiting the development of passivation film defects and enhancing the integrity and protection of the passivation film. The most significant effect is observed when the concentration of TCPP is 0.5 mmol/L. The physical adsorption of TCPP is primarily determined by the negative charge centers, namely the carboxyl group O and the pyrrole N. However, due to steric hindrance caused by the unrestricted rotation of the carboxyl benzene, the pyrrole N does not play a dominant role in chemical adsorption. Instead, the active site for chemical adsorption is the carboxyl group O. The adsorption process significantly reduces the diffusion coefficient of TCPP molecules, providing a robust and stable adsorption binding. Phthalocyanine molecules without carboxyl benzene groups adopt a planar structure, allowing them to form stable adsorption configurations on the iron surface through flat adsorption. This observation provides guidance for the design of novel metal phthalocyanine molecules. Specifically, the development of metal phthalocyanine molecules with modifying groups that are coplanar with the phthalocyanine ring and possess restricted rotation can achieve flat adsorption, improve coverage rate, and enhance adsorption configuration stability.

Core-shell Co-NC@NC nanomaterial for efficient oxygen reduction reaction

Transition metal and nitrogen doped carbons (M-N-C) catalysts present significant potential as substitutes for platinum-carbon (Pt/C) in catalyzing oxygen reduction reaction (ORR). Hence, we employ an epitaxial growth strategy to prepare Zn/Co-ZIF@ZIF-8 crystals with core-shell structure. Subsequent pyrolysis and acid etching produce highly porous cobalt-doped nitrogen materials for ORR investigation. The resulting Co-NC@NC catalyst demonstrates a graded porous structure alongside remarkable conductivity, possessing a specific surface area measuring 623 m2 g−1. It showcases heightened ORR activity with a half-wave potential (E1/2) of 0.886 V, superior kinetic performance (illustrated by an extremely low Tafel slope measuring 45.98 mV/dec), and strengthened stability (with mere 25 mV day after 40,000 cycles) when contrast with Pt/C catalysts in 0.1 M KOH. Additionally, it exhibits notable activity and stability in acidic environments. These remarkable attributes are attributable to the graded structure, which facilitates rapid mass transfer, a high electrochemically active area that exposes highly dispersed active sites, and a conductive carbon skeleton network that promotes electron transfer.

Surface modified FeCoZn-ZIF derived polyhedral electrocatalysts for ORR under alkaline and acidic conditions

Electrocatalysts for catalyzing oxygen reduction reactions at variable pH conditions are essential for energy conversion and storage. Herein, Fe@FeCoZn–CN electrocatalysts were prepared with internal and external doping approach. The Fe@FeCoZn–CN electrocatalyst exhibits a desirable ORR performance in both acid and alkaline electrolytes. Specifically, the half-wave potential (E1/2) of Fe@FeCoZn–CN electrocatalyst is 0.890 V which far beyond Pt/C electrocatalyst (0.839 V) in alkaline electrolyte. In addition, Fe@FeCoZn–CN electrocatalyst also exhibits improved ORR activity (E1/2 = 0.801 V) compared to Pt/C (0.797 V) electrocatalysts in acidic electrolytes. What's exciting is that the rechargeable ZABs based on Fe@FeCoZn–CN electrocatalysts exhibit an impressive performance with a favorable open-circuit potential of 1.517 V and a promising specific capacity is 833.7 mA h gzn−1, good charge/discharge cycle stability. The remarkable ORR catalytic performance of Fe@FeCoZn–CN electrocatalysts can be traced to the internal doping of metals which prevent excessive metal aggregation and surface modified which can increase the metal loading to expose more active sites.

Boosting oxygen reduction electrocatalytic performance of Cu-Nx by modulating electron structure via construction of Cu-Nx and Cu nanocluster coupling catalyst

The utilization of atom-dispersed Cu-Nx site catalysts holds significant promise as a replacement for commercial Pt/C catalyst in the context of oxygen reduction catalysts. However, practical application of these catalysts has been hindered by their insufficient catalytic activity. It is imperative to enhance the oxygen reduction reaction (ORR) catalytic activity of the Cu-Nx catalysts by manipulating electronic structure of the Cu-Nx site. This study presents the synthesis of a composite catalyst, formed by coupling Cu nanoclusters and Cu-Nx catalysts through pyrolysis of protein-Cu2+ gel followed by acid-leaching treatment. The resultant composite catalyst demonstrates superior ORR activity as compared to isolated Cu-Nx catalysts under alkaline conditions. Through density functional theory (DFT) calculations, the synergistic mechanism of the coupled Cu nanoclusters and Cu-Nx for ORR catalytic activity is elucidated. The proximity of the Cu nanoclusters (Cu4) to the central Cu atom of Cu-Nx (CuN4) in the composite catalyst causes a shift in the d-band center of the active Cu site towards the Fermi level. This shift strengthens the binding energy of O2 adsorption, reduces ORR overpotential, and combines with favorable electron transfer from Cu nanoclusters to Cu-Nx sites, thereby enhancing ORR activity. These findings contribute novel insights into the enhancement of ORR catalysis performance through the manipulation of electron structures via nano-sized metal clusters.

Dealloyed Pt74Ni26 and Pt26Ni74 Electrodeposited Thin Film Electrocatalysts for Oxygen Reduction

Electrodeposition and microstructure of thin films close to Pt75Ni25 and Pt25Ni75 stoichiometry are described and their catalytic oxygen reduction reaction performance, dealloying, and strain evolution detailed. Multiple techniques are used to characterize the morphology, crystalline structure, and chemical homogeneity of the as-deposited and dealloyed films. A fine-scale percolating network of lower-density regions is evident in the as-deposited Pt74Ni26 films while the as-deposited Pt26Ni74 films are more homogenous and compact. Electrodeposition is accompanied by development of significant in-plane tensile stress that increases at more negative growth potentials to reach 1.28 GPa for as-deposited Pt26Ni74. Dealloying of the near-surface regions of Pt74Ni26 is accompanied by limited expansion or opening of the low-density regions while massive dealloying of the highly stressed Pt26Ni74 results in shrinkage, extensive cracking, and formation of a bi-continuous nanoporous structure with an average pore diameter close to 5 nm. Relative to electrodeposited Pt, the alloy films exhibit enhanced area-specific oxygen reduction reaction activity (at 0.95 V vs RHE, iR-corrected) that amounts to a factor of 3.4 for dealloyed Pt74Ni26 and 5.1 for dealloyed Pt26Ni74 while the Pt-based mass activity increased by a factor of 5.1 and 12.3, for the respective films.

Catalyzing oxygen reduction reaction with a worm-like oxide Ca3Co2O6 in solid-oxide fuel cells

Catalyzing oxygen reduction reaction with a worm-like oxide Ca3Co2O6 in solid-oxide fuel cells

A Non‐Macrocycle Thiolate‐Based Cobalt Catalyst for Selective O2 Reduction into H2O

AbstractThe reduction of dioxygen to produce selectively H2O2 or H2O is crucial in various fields. While platinum‐based materials excel in 4H+/4e− oxygen reduction reaction (ORR) catalysis, cost and resource limitations drive the search for cost‐effective and abundant transition metal catalysts. It is thus of great importance to understand how the selectivity and efficiency of 3d‐metal ORR catalysts can be tuned. In this context, we report on a Co complex supported by a bisthiolate N2S2‐donor ligand acting as a homogeneous ORR catalyst in acetonitrile solutions both in the presence of a one‐electron reducing agent (selectivity for H2O of 93 % and TOFi=3 000 h−1) and under electrochemically‐assisted conditions (0.81 V <η<1.10 V, selectivity for H2O between 85 % and 95 %). Interestingly, such a predominant 4H+/4e− pathway for Co‐based ORR catalysts is rare, highlighting the key role of the thiolate donor ligand. Besides, the selectivity of this Co catalyst under chemical ORR conditions is inverse with respect to the Mn and Fe catalysts supported by the same ligand, which evidences the impact of the nature of the metal ion on the ORR selectivity.

Effects of Zr dopants on properties of PtNi nanoparticles for ORR catalysis: A DFT modeling.

Pt-based alloys, such as Pt3Ni, are among the best electrocatalysts for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. Doping of PtNi alloys with Zr was shown to enhance the durability of the operating ORR catalysts. Rationalizing these observations is hindered by the absence of atomic-level data for these tri-metallic materials, even when not exposed to the fuel cell operation conditions. This study aims at understanding structure-property relations in Zr-doped PtNi nanoparticles as a key to their ORR function. In particular, we calculated, using a method based on density functional theory, the most stable chemical orderings of pristine and Zr-doped Pt3Ni particles containing over 400 atoms. We thus clarify (i) preferential location and charge states of Zr atoms in the Pt3Ni NPs; (ii) effect of doping Zr atoms on the stability of the Pt skin of the Pt3Ni NPs; (iii) charge redistribution induced by Zr dopants; (iv) layer-by-layer atomic ordering in the Pt3Ni/Zr NPs with the increasing Zr content; and (v) effect of Zr atoms on the adsorption energies of O and OH species as indicators of the ORR activity.

Synthesis of PtNi Nanoparticles to Accelerate the Oxygen Reduction Reaction.

We report the synthesis of core-shell Ni-Pt nanoparticles (NPs) with varying degrees of crystallographic facets and surface layers rich in Pt via a seed-mediated thermolytic approach. Mixtures of different surfactants used during synthesis resulted in preferential surface passivation, which in turn dictated the size, chemical composition, and geometric evolution of these PtNi NPs. Electrochemical investigations of these pristine core-shell Ni-Pt structures in the oxygen reduction reaction (ORR) show that their catalytic functionalities outperform the commercial Pt/C reference catalyst. The enhanced electrocatalytic ORR performances of these Pt-based PtNi NPs are correlated with the weakened oxygen binding strength or surface-adsorbed hydroxyl (OH) species on active Pt surface sites induced by the downshift of the d-band center as a result of compressive strain effects. Our studies offer a robust synthetic approach for the development of core-shell nanostructures for enhanced ORR catalysis.

Cerium doped graphene-based materials towards oxygen reduction reaction catalysis

With the global transition towards cleaner energy and sustainable processes, the demand for efficient catalysts, especially for the oxygen reduction reaction, has gained attention from the scientific community. This research work investigates cerium-doped graphene-based materials as catalysts for this process with density functional theory calculations. The electrochemical performance of Ce-doped graphene was assessed within the computation hydrogen electrode framework. Our findings reveal that Ce doping, especially when synergized with an oxygen atom, shows improved catalytic activity and selectivity. For instance, Ce doping in combination with an oxygen atom, located near a border, can be selective for the 2-electron pathway. Overall, the combination of Ce doping with structural defects and oxygenated functions lowers the reaction free energies for the oxygen reduction compared to pure graphene, and consequently, might improve the catalytic activity. This research sheds light from a computational perspective on Ce-doped carbon materials as a sustainable alternative to traditional costly metal-based catalysts, offering promising prospects for green energy technologies and electrochemical applications.

Porphyrin-based frameworks and derivatives for the oxygen reduction reaction

The global energy crisis and environmental pollution issues caused by the continuous consumption of fossil fuels are increasingly becoming severe. Developing clean and sustainable hydrogen (H2) energy and corresponding storage and conversion devices have attracted increasing attention. The utilization of H2 energy highly depends on the fuel cell (FC). However, the slow kinetics of oxygen reduction reaction (ORR) on the cathode of FC cannot be improved without efficient catalysts. Currently, precious metal platinum (Pt) and its alloys are commonly used catalysts for ORR process. However, the scarcity and high cost of Pt hinder their large-scale practical application. To replace typical Pt-based catalysts, non-precious metal electrocatalysts have been investigated for ORR. Inspired by the catalytic ORR active center Fe porphyrin of cytochrome c oxidase in nature, metalloporphyrin-based frameworks and their derivatives have become promising electrocatalysts due to their abundant conjugated electronic structure, tunable functional groups, and large specific surface area. First, this review briefly introduces porphyrins and catalytic ORR mechanisms. Second, recent progress on porphyrin-based ORR catalysts including porphyrin-based frameworks, framework@substrate composites, and framework-based derivatives was summarized. Porphyrin-based frameworks mainly include metal-organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), and polymers constructed with porphyrin building blocks. Porphyrin-based framework@substrate composites were usually assembled and constructed to improve the electron transfer rate of frameworks. To further improve the conductivity, framework-based derivatives, usually named metal, nitrogen-doped carbon (M-N-C) materials, were synthesized through pyrolyzing frameworks at high temperatures. Finally, research challenges and directions of porphyrin-based electrocatalysts for ORR were discussed. This review is meaningful and enlightening for designing and developing other porphyrin-based electrocatalysts for ORR.

First-principle calculations study of oxygen reduction electrocatalyst: Single transition metal supported on a brand-new graphitic carbon nitride (g-C7N3) substrate

Single-atom catalysts (SACs) possess promising potential as materials to catalyze oxygen reduction reaction (ORR) on account of high atomic utilization efficiency, tunable electronic structure, and exceptional catalytic performance. The ORR activities of graphite carbonitride (g-C7N3) supported 3d, 4d, and 5d transition metals are investigated. Eleven kinds of TM-C7N3 structures have been found to have good stability by computing formation energy and dissolution potential. Furthermore, density of states analysis shows a strong interaction of the metal atom and the coordination N atoms, which gives satisfactory stability of TM-C7N3. Among eleven TM-C7N3, the binding energy of reaction species on Rh-C7N3, Ni-C7N3, and Pt-C7N3 are closer to those of Pt(111), showing that they have good ORR activity. In addition, good linear relationships exist between the adsorption free energy of *OH (∆G*OH) and that of *OOH and *O, implying that ∆G*OH can be put forward as a trustworthy activity descriptor. Promisingly, the ηORR values of Rh-C7N3, Ni-C7N3, and Pt-C7N3 are 0.32, 0.38, and 0.44 V, respectively, even lower than the overpotential value of Pt(111). This suggests that these three catalysts demonstrate superior catalytic activity compared to Pt(111).

Construction of Fe Nanoclusters/Nanoparticles to Engineer FeN4 Sites on Multichannel Porous Carbon Fibers for Boosting Oxygen Reduction Reaction

AbstractFe–N–C catalysts are emerging as promising alternatives to Pt‐based catalysts for the oxygen reduction reaction (ORR), while they still suffer from sluggish reaction kinetics due to the discontented binding affinity between the Fe‐N4 sites and oxygen‐containing intermediates, and unsatisfactory stability. Herein, a flexible multichannel carbon fiber membrane immobilized with atomically dispersed Fe‐N4 sites and neighboring Fe nanoclusters/nanoparticles (FeN4‐FeNCP@MCF) is synthesized. The optimized geometric and electronic structures of the Fe atomic sites brought by adjacent Fe nanoclusters/nanoparticles and hierarchically porous structure of the carbon matrix endow FeN4‐FeNCP@MCF with outstanding ORR activity and stability, considerably outperforming its counterpart with FeN4 sites only and the commercial Pt/C catalyst. Liquid and solid‐state flexible zinc–air batteries employing FeN4‐FeNCP@MCF both exhibit outstanding durability. Theoretical calculation reveals that the Fe nanoclusters can trigger remarkable electron redistribution of the FeN4 sites and modulate the hybridization of central Fe 3d and O 2p orbitals, facilitating the activation of O2 molecules and optimizing the adsorption capacity of oxygen‐containing intermediates on FeN4 sites, and thus accelerating the ORR kinetic. This work offers an effective approach to constructing coupling catalysts that have single atoms coexisting with nanoclusters/nanoparticles for efficient ORR catalysis.

Fe doped Co9S8 nanoparticles embedded in N, S co-doped porous carbon as an efficient bifunctional electrocatalyst for rechargeable Zn-air batteries

Transition metal sulfides embedded in co-doped porous carbon materials with nitrogen and sulfur are a promising catalyst that can effectively solve the problem of slow oxygen reduction reaction (ORR) kinetics. However, monometallic sulfides consisting of a single active component only have monofunctional catalytic activity and cannot effectively increase the rate of oxygen evolution reaction (OER), thus limiting the energy conversion efficiency of Zn-air batteries (ZAB). Herein, a unique silica template assisted in situ pyrolysis strategy is used to synthesize iron (Fe)-doped cobalt sulfide (Co9S8) nanoparticle embedded in a honeycomb nitrogen (N), sulphur (S) co-doped porous carbon (Fe/Co9S8@NSC) electrocatalyst. The introduction of Fe increases the active component of the catalyst and further enhances the catalytic ability of Co9S8 by optimizing the electronic structure through charge transfer effect. Therefore, the rich active sites of Fe/Co9S8 nanoparticles anchored in N, S co-doped carbon materials with rich pore structure enable the catalysts to have good bifunctional catalytic activities of ORR and OER. In particular, the Fe/Co9S8@NSC has a high half-wave potential of 0.82 V for catalytic ORR and only needs low overpotential of 332 mV at a current density of 10 mA cm−2 for catalytic OER. In addition, the Fe/Co9S8@NSC catalyst based rechargeable ZAB also exhibits a significant specific capacity of 734 mAh g−1 and prolonged stability of 270 h, which outperforms the bulk of recently reported catalysts based on transition metal sulfides-based catalysts. This research offers a workable method for producing metal sulfides catalysts with bifunctional catalytic activity.

Tuning ORR selectivity of π-conjugated cobalt corroles from 2e- to 4e-

Efficient oxygen reduction reaction (ORR) is crucial for the performance of fuel cells and other electrochemical devices. Seeking for stable and electrochemically selective 2e- and 4e- ORR electrocatalyst is yet a challenge, making the design extremely important and outmost of interest. In this study, we demonstrate a method to tune ORR selectivity by adjusting the local cobalt density through oligo-/polymerization of π-conjugated cobalt(III) A2B and A3-corroles to linear and two-dimensional matrix structures. These heterogeneous catalysts exhibit remarkable physicochemical properties, fast charge transfer kinetics, electrochemical reversibility, and high durability. Unselective three-electron transfer kinetics with n = 2.5–2.9 in between −0.20 V and +0.40 V vs. RHE are detected with the π-conjugated cobalt(III) A2B- corrole polymers. Highly selective four-electron kinetics with n = 3.7 in between −0.20 V and +0.40 V vs. RHE are detected by employing the cobalt A3-corrole oligomers during the ORR catalysis.

Transformation of Waste Agarwood Leaves into Heteroatom-Doped Microporous Carbon for Highly Active Metal-Free Catalytic Oxygen Reduction Reaction and Efficient Capacitive Energy Storage Application

Transformation of Waste Agarwood Leaves into Heteroatom-Doped Microporous Carbon for Highly Active Metal-Free Catalytic Oxygen Reduction Reaction and Efficient Capacitive Energy Storage Application

Density Functional Theory Investigation of Temperature-Dependent Properties of Cu-Nitrogen-Doped Graphene as a Cathode Material in Fuel Cell Applications

In this study, density functional theory (DFT) was used to investigate the influence of temperature on the performance of a novel Cu-nitrogen-doped graphene Cu2-N8/Gr nanocomposite as a catalyst for the oxygen reduction reaction (ORR) in fuel cell applications. Our DFT calculations, conducted using Gaussian 09w with the 3–21G/B3LYP basis set, focus on the Cu-nitrogen-doped graphene nanocomposite cathode catalyst, exploring its behavior at three distinct temperatures: 298.15 K, 353.15 K, and 393.15 K, under acidic conditions. Our analysis of formation energies indicates that the structural stability of the catalyst remains unaffected as the temperature varies within the potential range of 0–7.21 V. Notably, the stability of the ORR steps experiences a marginal decrease with increasing temperature, with the exception of the intermediate OH + H2O (*OH + H + *OH). Interestingly, the optimization reveals the absence of single OH and H2O intermediates during the reactions. Furthermore, the OH + H2O step is optimized to form the OH + H + OH intermediate, featuring the sharing of a hydrogen atom between dual OH intermediates. Free energy calculations elucidate that the catalyst supports spontaneous ORR at all temperatures. The highest recorded maximum cell potential, 0.69 V, is observed at 393.15 K, while the lowest, 0.61 V, is recorded at 353.15 K. In particular, the Cu2-N8/Gr catalyst structure demonstrates a reduced favorability for the H2O2 generation at all temperatures, resulting in the formation of dual OH intermediates rather than H2O2. In conclusion, at 393.15 K, Cu2-N8/Gr exhibits enhanced catalyst performance compared to 353.15 K and 298.15 K, making it a promising candidate for ORR catalysis in fuel cell applications.

Design of NiCo2S4@ZnAl-LDH/TiO2@MXene synthesis as promising cathode catalyst for enhancing electrochemical performance in microbial fuel cell

In this work, a double-bimetallic compound (NiCo2S4@ZnAl-LDH/TiO2@MXene) was successfully prepared by a simple hydrothermal-coprecipitation method. NiCO2S4@ZnAl-LDH/TiO2@MXene was combined with two bimetallic compounds, NiCo2S4@ZnAl-LDH and TiO2@MXene, which formed a firm structure. This material showed superior catalytic oxygen reduction reaction (ORR) according to the large integral area and sharp slope. The maximum power density of NiCo2S4@ZnAl-LDH/TiO2@MXene-microbial fuel cell (MFC) was 565.81 mW/m2 and could be maintained for 10 d, which was 7.07 times of NiCo2S4/TiO2@ZnAl-LDH-MFC (80 mW/m2), 11.43 times of NiCo2S4@ZnAl-LDH (49.5 mW/m2), 14.15 times of TiO2@MXene (40 mW/m2), indicating the excellent electrical performance of NiCo2S4@ZnAl-LDH/TiO2@MXene. TiO2 and NiCo2S4 were introduced in ZnAl-LDH and MXene separately to avoid aggregation between layers, which provided more pathways for ions and accelerated the speed of the transportation of electrons. NiCO2S4@ZnAl-LDH/TiO2@MXene were coated tightly and firmly with the coprecipitation method which further enhanced the electrochemical performance of MFC. Therefore, this study would give a boarder horizon about the application of cathode materials of MFC.

Anion effect on oxygen reduction reaction activity of nitrogen doped carbon nanotube encapsulated cobalt nanoparticles

In this work, we report the diverse cobalt precursors for the synthesis of nitrogen doped carbon nanotubes encapsulated Co nanoparticles (Co@NCNT) as oxygen reduction reaction (ORR) electrocatalyst to verify the anion effect. The X-ray photoelectron spectroscopy (XPS) test indicates that more pyridinic and pyrrolic N species coordinate with Co atoms for cobalt chloride (CoCl2) due to more defective sites on NCNT etched by chlorine compared to the counterparts of cobalt nitrate (Co(NO3)2), cobalt acetate (Co(Ac)2) and cobalt triacetoacetate (Co(acac)2). With higher content of Co–Npyridinic+pyrrolic structures, Co@NCNT-Cl exhibits a robust ORR performance highlighted by half-wave potential of 880 mV vs. RHE, corresponding to a 4-fold better kinetic current density than commercial Pt/C. The superior catalytic activity toward ORR originates from more Co–Npyridinic+pyrrolic structures efficiently hydrogenated the adsorbed O2 to *OOH intermediate; additionally, its low binding strength with *OOH allows the mobility to metallic Co for splitting to generate O* species. Thus, a relay ORR catalysis is noticed for Co@NCNT-Cl. The assembled rechargeable zinc-air battery (ZAB) reaches a power density of 152 mW cm−2 sustained for 500 h, superior to Pt/C-IrO2. Moreover, the all-solid-state ZAB delivers a maximum power density of 54 mW cm−2 and maintains for 30 h.