Electrocatalysts For Oxygen Reduction Reaction Research Articles

Study of oxygen reduction reaction on binuclear-phthalocyanine with Fe-Fe, Co-Co, and Fe-Co dual-atom-active sites using density functional theory

Although the N4-macrocyclic ligands have been used to develop single-atom catalysts (SACs), their utilization for the construction of dual-atom catalysts (DACs) for electrocatalytic oxygen reduction reaction (ORR) is poorly investigated. Herein, a binuclear phthalocyanine (bN-Pc) was explored as a theoretical model for the construction of FeFe-bN-Pc, CoCo-bN-Pc, and FeCo-bN-Pc dual-atom-site configurations and their ORR activity along with mechanisms were investigated systematically in alkaline media, using density functional theory (DFT) calculations. The results indicated that the dual-atom-bN-Pc models, having close proximity between adjacent metals, invited individual O-atom of O2 for coordination on both sites, forming a cis-bridged-O2 adduct. The Gibbs free energy studies showed that the decomposition of O2 on dual-atom sites was the rate-determining step, and the Fe-Co-bN-Pc had a lower energy barrier (0.591 eV) for this step as compared to Fe-Fe-bN-Pc (0.641 eV) and Co-Co-bN-Pc (0.692 eV), which justifies its stronger ORR performance. The synergistic effect of Fe-Co collaboration, the close proximity of Fe-Co, and the significant e- donation from the 3d-orbital of active sites into the *orbital of O2 can be attributed to this decrease in limiting the potential for the rate-determining step on Fe-Co-bN-Pc. For future ORR electrocatalysts, this work offers a scientific and engineering perspective on the construction of dual-atom active sites employing molecular moieties.

Iron and nitrogen co-modified multi-walled carbon nanotubes for efficient electrocatalytic oxygen reduction

Multi-walled carbon nanotubes (MWCNTs) with one-dimensional nanostructure are an ideal support for oxygen reduction reaction (ORR) catalysts thanks to their intrinsic outstanding electrical conductivity and high specific surface area. Iron and nitrogen doping could alter the local electronic structure and therefore enhance the ORR activity of MWCNTs, but the preparation process always includes complicated growth conditions and post-treatment. Herein, an iron and nitrogen co-modified multi-walled carbon nanotubes (Fe–N-MWCNTs) with hierarchical nanostructure is engineered and synthesized via a simple two-step pyrolysis approach. Large specific surface area, low resistivity, and intensified charge density near the Fermi level synergistically endow the Fe–N-MWCNTs with outstanding ORR activity. The optimal Fe–N-MWCNTs exhibit a higher onset potential value of 0.92 V (versus RHE) and half-wave potential (E 1/2) of 0.85 V (versus RHE) in 0.1 M KOH medium, which exceeds the benchmark Pt/C electrocatalyst (E 1/2 = 0.84 V). This strategy of modifying MWCNTs support by a simple calcination process provides a feasible method to prepare cost-efficient ORR electrocatalysts.

Pt-based Rare Earth Alloy as Efficient and Robust Electrocatalyst for High-temperature Proton Exchange Membrane Fuel Cells.

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) are crucial in future energy system. However, the activity and stability of the electrocatalysts are severely restricted by high temperature and phosphoric acid poisoning. Herein, PtCe alloy as oxygen reduction reaction (ORR) electrocatalyst for HT-PEMFCs exhibits fantastic performance. Ce can increase the electronic density of Pt weakening phosphoric acid poisoning and improving ORR activity. The optimized electronic structure can also reduce the dipole effect between Pt and O, which suppresses the irreversible oxidation of Pt. Additionally, the dramatically negative heat of formation in PtCe catalyst brings high kinetic barrier of metal diffusion and dissolution. With this electrocatalyst, the HT-PEMFCs show a preeminent peak power of 605 mW cm-2 with 0.3 mgPt cm-2. After 30000 cycles of accelerated stability test, the peak power density only decreases by 31.6 %, achieving the goal of Department of Energy in 2020 (＜40 % loss).

Catalytic upcycling of waste polypropylene for gram-scale production of FeCo@N-doped carbon nanotubes toward efficient oxygen reduction electrocatalysis

Exploring novel low-cost and high-efficiency non-precious metal catalysts for use in oxygen reduction reactions (ORR) is of key importance. Based on catalytic pyrolysis of waste plastics, a facile method for preparing N-doped Fe/Co-encapsulated carbon nanotubes (FexCoy@NCNTs) was proposed. Particularly, gram-scale yield of the composite catalyst (3.87 g) was achieved in one pot with considerable atomic conversion rate of carbon (∼57.3 %) from waste polypropylene to high-quality CNTs, suggesting great potential for waste plastics valorization. The effects of Fe-to-Co ratios were studied by testing the ORR performance of each sample, indicating that as the Fe proportion increased, the ORR performance initially increased and then decreased. The Fe1Co1@NCNTs catalyst showed optimal performance which was comparable with commercial Pt/C catalyst: Particularly, an initial potential of 0.97 V vs RHE, a half-wave potential of 0.81 V vs RHE, and a limiting current density of –5.68 mA cm−2 were recorded. The encapsulated Fe and Co species in N-doped CNTs enhanced catalytic activity, while the porous carbon structure augmented the exposure of active sites. This strategy offers an auspicious platform for reusing waste plastics in the mass production of CNTs, and also provides an innovative approach for preparing low-cost, high-performance, and non-precious metal-based electrocatalysts for ORRs.

Scalable and Controllable Synthesis of Pt‐Ni Bunched‐Nanocages Aerogels as Efficient Electrocatalysts for Oxygen Reduction Reaction

AbstractDeveloping efficient and stable Pt‐based oxygen reduction reaction (ORR) electrocatalysts via both economical and controllable routes is critical for the practical application of electrochemical energy devices. Herein, a scalable, controllable, and general ambient‐O2‐involved aqueous‐solution cultivating strategy to prepare PtxMy (M = Ni, Fe, Co) bunched‐nanocages aerogels (BNCs AG) is demonstrated, based on a newly established high‐M‐to‐Pt‐precursor‐ratio‐and‐B‐incorporation‐facilitated M‐rich core and Pt‐rich shell hydrogel formation process. The Pt83Ni17 BNCs AG shows prominent ORR performance with a mass activity (MA) of 1.95 A mgPt−1 and specific activity of 3.55 mA cm−2, which are 8.9‐times and 9.6‐times that of Pt supported on carbon (Pt/C), respectively. Particularly, the Pt83Ni17 BNCs AG displays greatly enhanced durability (MA 82.6% retention) compared to Pt/C (MA 31.8% retention) after a 20 000‐cycles accelerated durability test. Systematic studies including density functional theory calculations uncover that the excellent activity is closely related to the optimized ligand and strain effects with the optimized Ni content in this aerogel; the outstanding durability is endowed by the lowered‐down Ni leaching with the optimized Pt/Ni ratio and the inhibited sintering due to its appropriate porosity. This work provides new perspectives on the development of electrocatalysts with both high performance and low cost.

Litchi‐derived platinum group metal‐free electrocatalysts for oxygen reduction reaction and hydrogen evolution reaction in alkaline media

AbstractWithin the framework of the circular economy, the waste litchi's skins were upgraded and transformed into electrocatalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). The waste litchi's skins were pyrolyzed, activated, and then used as carbon support for fabricating metal–nitrogen–carbons (M–N–Cs) which belong to a promising class of platinum group metal‐free electrocatalysts. The activated char was functionalized with transition metal (Fe, Ni, and Co)‐ phthalocyanine (Pc) in monometallic and bimetallic fashion by subjecting it to a thermal treatment at 600 and 900°C. The samples functionalized at 900°C showed higher performance for HER due to the formation of metal nanoparticles, whereas the samples functionalized at 600°C showed higher performance for ORR. Particularly, sample Ni–Co 900 had an overpotential of −0.38 V for HER, while the sample Fe 600 was the most active electrocatalyst for ORR by demonstrating the onset potential of ∼0.9 V (a half‐wave potential of ∼0.81 V) with the least production of unwanted peroxide anion.

Nitrogen, sulfur, and oxygen tri-doped carbon nanosheets as efficient multifunctional electrocatalysts for Zn-air batteries and water splitting

Nitrogen, sulfur, and oxygen tri-doped carbon nanosheets (N, S, O-CNs) were prepared by a modified in-situ g-C3N4 template method with a plant-waste, rice straw, as the carbon precursor. The N, S, O-CNs could worked as efficient electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Significantly, the introduced S element can particularly activate the electron transfer and accelerate reaction kinetics for HER, while the N/O dopants can efficiently promote the ORR and OER. As a result, the N, S, O-CNs exhibited excellent performance with favorable kinetics and decent durability as a multifunctional ORR, OER and HER catalyst. Moreover, the rechargeable liquid/solid Zn−air battery and water splitting device showed superior performance by assembling this N, S, O-CNs catalyst. This work paves a universal avenue towards further development of plant-waste derived carbon materials with heteroatom dopants as the highly efficient electrocatalysts in energy devices.

Ultrathin PdCu Nanosheet as Bifunctional Electrocatalysts for Formate Oxidation Reaction and Oxygen Reduction Reaction.

The development of robust nonplatinum electrocatalysts to enhance the performance of formate oxidation reaction (FOR) and oxygen reduction reaction (ORR) is one of the key issues for the commercialization of direct formate fuel cells (DFFCs), but still challenging. Herein, a structurally controlled 3D flower-like PdCu nanosheet (NS) catalyst is synthesized by a method of oil bath reduction under mild conditions as a bifunctional electrocatalyst for DFFCs. Under the dual tuning on the composition and intermetallic phase, the PdCu nanosheet catalyst exhibits 8.67 times higher mass activity for anodic formate oxidation reaction than the commercial Pd/C. For the cathodic ORR, a positive shift half-wave potential is obtained for PdCu nanosheets exceeding Pt/C. Moreover, after a long-term stability test, the current density of the PdCu nanosheet catalyst for FOR and ORR can be well maintained with the least activity decay. When the PdCu NSs are used as optimized anode and cathode electrodes for DFFCs enable a peak power density as high as 53 mW cm-2 at room temperature, which is about 1.3 times higher than that of the commercial Pd/C and Pt/C as anode and cathode electrodes. This work provides a potential strategy to improve the catalytic performance of non-Pt-based nanocatalysts.

Highly Stable Pt-Based Oxygen Reduction Electrocatalysts toward Practical Fuel Cells: Progress and Perspectives

The high cost and poor reliability of cathodic electrocatalysts for the oxygen reduction reaction (ORR), which requires significant amounts of expensive and scarce platinum, obstructs the broad applications of proton exchange membrane fuel cells (PEMFCs). The principles of ORR and the reasons for the poor stability of Pt-based catalysts are reviewed. Moreover, this paper discusses and categorizes the strategies for enhancing the stability of Pt-based catalysts in fuel cells. More importantly, it highlights the recent progress of Pt-based stability toward ORR, including surface-doping, intermetallic structures, 1D/2D structures, rational design of support, etc. Finally, for atomic-level in-depth information on ORR catalysts in fuel cells, potential perspectives are suggested, such as large-scale preparation, advanced interpretation techniques, and advanced simulation. This review aims to provide valuable insights into the fundamental science and technical engineering for practical Pt-based ORR electrocatalysts in fuel cells.

The optimization of iron porphyrin@MOF-5 derived Fe[sbnd]N[sbnd]C electrocatalysts for oxygen reduction reaction in zinc-air batteries

The development of non-precious metal catalysts (NPMC) for oxygen reduction reactions (ORR) is a hot topic for fuel cells and zinc-air batteries (ZABs). This study reports a method to obtain efficient FeNC ORR catalysts via doping dicyandiamide and iron porphyrins on the pyrolyzed MOF-5 and followed pyrolysis to achieve the anchoring of Fe-Nx active sites onto square-shaped structure carbon material. The prepared FeNC catalysts exhibit excellent ORR performance under an alkaline environment with half-wave potentials up to 0.903 V, which is 57 mV higher than that of Pt/C under the same conditions. It has excellent stability and methanol resistance. Moreover, this catalyst exhibited high specific capacity (821.8 mAh g−1) and power density (111.7 mW cm−2) in assembled ZAB, and excellent charging and discharging stability.

“Substituents optimization” and “push effect” dual strategy for design of cobalt phthalocyanine catalyst on oxygen reduction reaction

Molecular metallocycle electrocatalysts like metalloporphyrins and metallophthalocyanines were found to be effective for oxygen reduction reaction (ORR) due to their M–N4 active sites and large conjugated electronic molecular structures. Herein, the “substituents optimization” strategy combined with “push effect” modification was innovatively employed to target a single Co–N4 active site in three substituted phthalocyaninato cobalt complexes: tetranitrophthalocyaninato cobalt (CoTNPc), tetra(4-nitrophenoxy) phthalocyaninato cobalt (CoTPNPc), and tetraphenoxy phthalocyaninato cobalt (CoTPPc) electrocatalyst, also with 4-phenylpyridine axial coordination on Co–N4 unit. Through substituents screening, the half-wave potential (E1/2) for ORR increases in the order of CoTPNPc (0.75 V) < CoTPPc (0.80 V) < CoTNPc (0.83 V) along with decreased electron-withdrawing ability of their substituents from –OC6H4–NO2, –OC6H5 to –NO2 in the three cobalt phthalocyanine derivatives. CoTNPc with the weakest electron-withdrawing substituent exhibits the best ORR performance among the three compounds. This is attributed to its higher electron delocalization and lifted HOMO energy level with the lower energy barrier in the rate-determining step relative to the other two compounds, which facilitate the electron transfer and reduction of oxygen as evidenced by XPS, UPS, and DRS analysis combined with DFT calculations. Further coordination of 4-phenylpyridine shifts the E1/2 up to 0.78, 0.82, and 0.85 V for CoTPNPc, CoTPPc, and CoTNPc. DFT calculations demonstrate that the introduction of the electron-donating phenylpyridine ligand into the cobalt phthalocyanines breaks the symmetry of the Co–N4 center and also raises the electron density of Co sites, which promotes O2 adsorption and improves ORR performance. After comparing the two strategies, the substituents on metallophthalocyanine are more determined by the electroactivity than the axial group, which directly regulates the coordination environment and then the activation barrier of the ORR process. This work provides theoretical and experimental guidance by two coupling strategies for the design of highly active molecular CoPc-based ORR electrocatalysts in the practical application.

N, S dual-doped carbon aerogels-supported Co9S8 nanoparticles as efficient oxygen reduction reaction electrocatalyst for zinc-air battery

The innovative design of highly active and noble-metal-free electrocatalysts for the oxygen reduction reaction (ORR) is urgently required for the widespread application of Zinc-air batteries (ZABs). This study presents a porous composite, Co9S8 @NSC, which integrates N and S co-doped carbon aerogels with Co9S8 nanoparticles to create ideal ORR electrocatalysts. The porous carbon aerogels posesess a high specific surface area, which offers abundant catalytic sites and efficient channels for the reactants and electrolytes, while maintaining a uniform distribution of nanoparticles during long-term operation. The collaboration of ORR-active Co9S8 nanoparticles and N and S co-doped carbon aerogels significantly improves ORR performance. Co9S8 @NSC demonstrates a competitive ORR activity, including a high half-wave potential (E1/2, 0.85 V), fast electron transfer kinetics (Tafel slop, 53.3 mV dec−1), and prominent long-term stability. When utilized as an air cathode catalyst in primary Zn-air batteries, the Co9S8 @NSC electrode displays a power density of 150.9 mW cm−2 and a specific capacity of 735 mAh gzn−1. Overall, this work presents a promising electrocatalyst design for ORR, which could greatly benefit the development of ZABs.

Giving New Life to Waste Cigarette Butts: Transformation into Platinum Group Metal-Free Electrocatalysts for Oxygen Reduction Reaction in Acid, Neutral and Alkaline Environment

Following the core theme of a circular economy, a novel strategy to upcycle cigarette butt waste into platinum group metal (PGM)-free metal nitrogen carbon (M-N-C) electrocatalysts for oxygen reduction reaction (ORR) is presented. The experimental route was composed of (i) the transformation of the powdered cigarette butts into carbonaceous char via pyrolysis at 450 °C, 600 °C, 750 °C and 900 °C, (ii) the porosity activation with KOH and (iii) the functionalization of the activated chars with iron (II) phthalocyanine (FePc). The electrochemical outcomes obtained by the rotating disk electrode (RRDE) technique revealed that the sample pyrolyzed at 450 °C (i.e., cig_450) outperformed the other counterparts with its highest onset (Eon) and half-wave potentials (E1/2) and demonstrated nearly tetra-electronic ORR in acidic, neutral and alkaline electrolytes, all resulting from the optimal surface chemistry and textural properties.

Synthesis of bimetallic PtxWySz nanocrystals as potential cathodic electrocatalysts for Proton Exchange Membrane Fuel Cell

Chalcogenides Pt-based materials have been explored due to their potential use in Proton Exchange Membrane Fuel Cells (PEMFCs). This paper presents mixed platinum tungsten sulfide nanocrystals (PtxWySz) prepared by thermal treatment as a new cathodic electrocatalyst for Oxygen Reduction Reaction (ORR). Physical characterization and electrochemical evaluation of two different metallic proportions (1:4 and 1:6 wt/wt of (NH4)2PtCl6 and NH4WS4 salts precursors) show that W-S provide higher activity for ORR and high poison tolerance to CO adsorption, at lower Pt loading. Thermogravimetric analysis (TGA), SEM-EDS, and ICP results are presented and match each other. XRD patterns present characteristic peaks of Pt, WO3, and PtW phases. TEM images confirm the morphology and nanoparticle size of PtxWySz. It was found a more positive onset potential and larger electrochemical surface area for the PtxWySz compared to Pt/C.

BN/Cu/CNT nanoparticles as an efficient tri-functional electrocatalyst for ORR and OER

Preparing economic, stable, and highly efficient non-precious-metal materials for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance to the development of storage technologies and energy conversion. In this manuscript, we report a novel Cu based nano-catalyst as an electrode material fabricated by complexation-reduction method. Benefit from the stable of h-NB and the good electrical conductivity of CNT, the tri-functional electrocatalyst BN/Cu/CNT displays enhanced activity towards ORR and with the high current density of 0.95 mA/cm2, which is comparable to that of commercial Pt/C catalyst (cathodic peak current: 1.05 mA/cm2). The BN/Cu/CNT also demonstrates high catalyst activity for the OER. From the rotating disk electrode and rotating ring-disk electrode tests, the number of electrons exchanged during the ORR is revealed to be 3.92, suggesting a 4e− pathway of O2 reduction to H2O. The as prepared catalyst also has good stability and superior methanol tolerance to the commercial Pt/C catalyst in alkaline medium. Thus, it is anticipated that the BN/Cu/CNT catalyst is surely helpful for providing a new space to develop Pt-free catalyst.

N-doping carbon-coated Cu@C(N) nanocapsules synthesized by arc plasma toward high-performance ORR electrocatalyst

The development of efficient and cost-effective methods for the synthesis of non-precious metal as the catalytic material for oxygen reduction reaction (ORR) is addressing a key barrier to fuel cell deployment in a wide range of applications. In this study, core-shell carbon-coated copper nanoparticles (Cu@C) were prepared using arc discharge plasma under argon and hydrogen atmospheres. And nitrogen doping was achieved during the subsequent heat treatment using dicyandiamide as the nitrogen source. The results showed that the catalysts had better ORR catalytic activity, better stability and better methanol tolerance than Pt/C, and the ORR reaction process was nearly four-electron pathway. The successful doping of nitrogen increased the reaction sites. And the addition of copper core improved the conductivity of the catalytic material. Meanwhile, the N-C shell layer protected the Cu nanoparticles from dissolving in aqueous solutions or being chemically oxidized, facilitating the electronic interaction of the core Cu nanoparticles with the N-C shell layer. This study provides an insight into the preparation of high-efficiency non-precious metal-based ORR electrocatalysts by DC arc plasma, a beneficial method.

Direct Oxygen‐Oxygen Cleavage through Optimizing Interatomic Distances in Dual Single‐atom Electrocatalysts for Efficient Oxygen Reduction Reaction

AbstractThe oxygen reduction reaction (ORR) on transition single‐atom catalysts (SACs) is sustainable in energy‐conversion devices. However, the atomically controllable fabrication of single‐atom sites and the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct O−O cleavage pathway through using a bi‐functional ligand‐assisted strategy to pre‐control the distance of hetero‐metal atoms. Concretely, the as‐synthesized Fe−Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half‐wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the Fe−Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero‐diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.

Direct Oxygen-Oxygen Cleavage through Optimizing Interatomic Distances in Dual Single-atom Electrocatalysts for Efficient Oxygen Reduction Reaction.

The oxygen reduction reaction (ORR) on transition single-atom catalysts (SACs) is sustainable in energy-conversion devices. However, the atomically controllable fabrication of single-atom sites and the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct O-O cleavage pathway through using a bi-functional ligand-assisted strategy to pre-control the distance of hetero-metal atoms. Concretely, the as-synthesized Fe-Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half-wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the Fe-Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero-diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.

String of ZIF-derived hollow beaded nanocage embedded into carbon nanofiber with intensified exposed Co-Nx sites for efficient oxygen catalysis in various fuel cell devices

The rational control of Co-Nx active sites dispersion in nanomaterials is significant to construct efficient oxygen reduction reaction (ORR) electrocatalysts in fuel cells. Herein, a novel strategy for the scalable synthesis of carbon nanofiber supported hollow beaded nanocage with accessible Co-Nx sites in cavity wall (PAN-Co-ZIF-8-C-A and PAN-Co/ZIF-8-C-A) originated from zeolitic imidazolate frameworks (ZIFs) and polyacrylonitrile (PAN) is reported. Remarkably, the formed samples modified with Co-Nx sites exhibit superior ORR activity, which makes it promising ORR catalysts for microbial fuel cell (MFC) and direct methanol fuel cell (DMFC). Accordingly, the maximum power densities of MFC decorated with PAN-Co-ZIF-8-C-A and PAN-Co/ZIF-8-C-A achieve 869.6 and 888.3 mW cm−2, which are 1.17 and 1.19 times higher than that of Pt/C. In addition, the PAN-Co/ZIF-8-C-A modified DMFC exhibits comparable power density of 23.27 mW cm−2 close to Pt/C electrode (25.63 mW cm−2). Such commendable catalytic performances can be primarily attributed to the synergistic effect of hierarchical porosity for fast mass transport, high conductivity for electron migration, and well-tuned Co-Nx sites for oxygen reduction. This facile-effective optimization strategy may open a new avenue for exposing the catalytic centers of one-dimensional (1D) nanofiber and ZIFs-derived oxygen catalyst in fuel cells.

Dispersed cobalt nanoparticles in the nitrogen doped carbon black as efficient catalysts for oxygen reduction reaction and Zinc-Air batteries

Developing an effective and durable Pt-free oxygen reduction reaction (ORR) catalyst for Zinc-Air batteries (ZABs) is propitious to easing the energy and pollution crisis. Herein, we have prepared Co nanoparticles/N-doped carbon (Co/N/C) with tunable Co contents by the pyrolysis of polydopamine-coated cobalt phthalocyanine/carbon black precursors. Benefiting from the well-dispersed Co nanoparticles and the formation of various active sites (i.e. pyridinic, graphitic N and Co-Nx), the resulting Co/N/C-2.86 wt% catalysts possess a half-wave potential of 0.84 V and a mass activity of 5.18 A/g, illustrating the superior ORR performance. Noteworthy, the ZABs with the cathode of Co/N/C-2.86 wt% display an outstanding cell performance with a large open-circuit voltage (1.542 V), a high specific discharge capacity (744 mAh g−1) and an excellent maximum power density (236 mW cm−2). This work offers a promising approach to rationally design and fabricate high-performance ORR electrocatalysts for advanced ZABs.