Efficient Oxygen Reduction Reaction Catalysts Research Articles

The Recent Progress of Oxygen Reduction Electrocatalysts Used at Fuel Cell Level.

Proton exchange membrane fuel cells (PEMFCs) are gaining significant interest as an attractive substitute for traditional fuel cells, with higher energy density, lower environmental pollution, and better operation efficiency. However, the cathode reaction, i.e., the oxygen reduction reaction (ORR), is widely proved to be inefficient, and therefore an obstacle to the widespread development of PEMFCs. The requirement for affordable highly-efficient ORR catalysts is extremely urgent to be met, especially at fuel cell level. Unfortunately, most previous reports focus on the ORR performance at rotating disk electrodes (RDE) level instead of membrane electrode assembly (MEA) level, making it harder to evaluate ORR catalysts operating under real vehicle conditions. Obviously, it is extremely necessary to develop an in-depth understanding of the structure-activity relationship of highly-efficient ORR catalysts applied at MEA level. In this work, an overview of the latest advances in ORR catalysts is provided with an emphasis on their performance at MEA level, hoping to cover the novel and systemic insights for innovative and efficient ORR catalyst design and applications in PEMFCs.

A lignin–derived N-doped carbon-supported iron-based nanocomposite as high-efficiency oxygen reduction reaction electrocatalyst

Fuel cells are a promising renewable energy technology that depend heavily on noble metal Pt-based catalysts, particularly for the oxygen reduction reaction (ORR). The discovery of new, efficient non-precious metal ORR catalysts is critical for the continued development of cost-effective, high-performance fuel cells. The synthesized carbon material showed excellent electrocatalytic activity for the ORR, with half-wave potential (E1/2) and limiting current density (JL) of 0.88 V and 5.10 mA·cm−2 in alkaline electrolyte, respectively. The material has a Tafel slope of (65 mV dec−1), which is close to commercial Pt/C catalysts (60 mV dec−1). Moreover, the prepared materials exhibited excellent performance when assembled as cathodes for zinc-air batteries. The power density reached 110.02 mW cm−2 and the theoretical specific capacity was 801.21 mAh g−1, which was higher than that of the Pt/C catalyst (751.19 mAh g−1). In this study, with the assistance of Mg5(CO3)4(OH)2·4H2O, we introduce an innovative approach to synthesize advanced carbon materials, achieving precise control over the material's structure and properties. This research bridges a crucial gap in material science, with potential applications in renewable energy technologies, particularly in enhancing catalysts for fuel cells.

The Contact Interface Electronic Coupling of Cobalt and Zirconia Enables Stable and Highly Efficient 4e- Oxygen Reduction ReactionCatalysis.

Cobalt (Co) is an efficient oxygen reduction reaction (ORR) catalyst but suffers from issues of easy deactivation and instability. Here, it shows that ZrO2 can stabilize Co through interface electron coupling and enables highly efficient 4e- ORR catalysis. Porous carbon nanofibers loaded with dispersed Co-nanodots (≈10nm, 9.63wt%) and ZrO2 nanoparticles are synthesized as the catalyst. The electron transfer from the metallic Co to ZrO2 causes interface-oriented electron enrichment that promotes the activation and conversion of O2, improving the efficiency of 4e- transfer. Moreover, the simulation results show that ZrO2 acts like an electron reservoir to store electrons from Co and slowly release them to the interface, solving the easy deactivation problem of Co. The catalyst exhibits a high half-wave potential (E1/2) of 0.84V, which only decreases by 3.6mV after 10000 cycles, showing great stability. Particularly, the enhanced spin polarization of Co in a magnetic field reinforces the interface electron coupling that increases the E1/2 to 0.864V and decreases the energy barrier of ORR from 0.81 to 0.63eV, confirming that the proposed strategy is effective for constructing efficient and stable ORR catalysts.

Co3Fe7/CoCx nanoparticles encapsulated in nitrogen-doped carbon nanotubes synergistically promote the oxygen reduction reaction in Zn-air batteries

Efficient and stable non-precious metal catalysts (NPMCs) for the oxygen reduction reaction (ORR) are crucial for the advancement of Zn-air batteries. Herein, we report a supramolecular self-scarifying template and confinement pyrolysis strategy to obtain an efficient ORR catalyst of well-dispersed Co3Fe7/CoCx heterostructure nanoparticles encapsulated by nitrogen-doped carbon nanotubes (Co3Fe7/CoCx@N-CNT). The as-synthesized Co3Fe7/CoCx@N-CNT catalyst exhibited outstanding ORR activity, with a half-wave potential of 0.88 V versus a reversible hydrogen electrode, and good stability. The Zn-air battery based on the Co3Fe7/CoCx@N-CNT cathode achieved a peak power density of 265 mW cm−2 and a durability of over 200 h, which is superior to most reported NPMCs and even the Pt/C counterpart. The physical characterization and electrochemical poisoning experiments revealed that the Co3Fe7/CoCx nanoparticles in the core along with pyridine N and Fe–Nx hosted in the carbon nanotube all acted as active sites for the ORR. Further theoretical calculations showed that the charge redistribution between the Co3Fe7/CoCx nanoparticles and the Fe–Nx carbon overlayers downshifted the d-band center of Fe and optimized the adsorption ability, which boosted the ORR kinetics. This work provides an effective strategy to synthesize non-precious metal ORR catalysts with multiple active sites and highlights the synergistic role of encapsulated nanoparticles and carbon support.

One-step synthesis of thin-carbon-shell-encapsulated binary cobalt chromium nitrides for oxygen reduction reaction

Hydrogen fuel cells are expected to be widely used in transportation and portable power generation. Unfortunately, sluggish cathodic oxygen reduction reaction (ORR) kinetics hamper the commercial application of the fuel cells. The quest for cost effective and highly efficient ORR catalysts is of great importance. Transition metal nitride (TMN) has received widespread attention mainly for its Pt-like characteristics. Here, we propose a new one-step “NH3-free” synthesis of thin-carbon-shell-encapsulated binary cobalt chromium nitrides (Co-CrN@C) using 1,2,4-1H-triazole as the nitrogen/carbon source. The Co-CrN@C exhibits almost ideal four-electron reduction of oxygen and achieves remarkable long-term durability and better methanol tolerance due to high-degree graphitization of the carbon shell. The X-ray photoelectron spectra and the density functional theory calculations unveil the origin of the intrinsic activity of the catalyst and the reaction mechanism. Furthermore, Co-CrN@C exhibits an impressive peak power density (PPD) of 488 mW cm−2, surpassing the 423 mW cm−2 for the Pt/C-driven anion exchange membrane fuel cells. These findings offer an indispensable strategy for rational design of high-efficient and durable non-noble catalysts.

Electronic structure modification of FeWO4 through F doping for enhanced oxygen reduction performance in zinc–air batteries

Exploring efficient and stable oxygen reduction reaction (ORR) catalysts for zinc-air batteries (ZABs) holds tremendously significant. Tungsten-based materials have attracted the attention of researchers thanks to abundant resources and excellent stability. Nevertheless, due to the strong adsorption energy for O-containing intermediates, *O and *OH are difficult to desorb from tungsten-based materials during ORR. Here, an F-doping strategy was employed to construct F-doped FeWO4 species composited on a multi-dimensional N-doped carbon (F–FeWO4/NC) as the ORR catalyst for ZABs. The incorporation of F atoms into the main lattice of FeWO4 enhanced the polarity of chemical bonds in FeWO4 through hydrogen bond interactions between H2O molecules and F atoms, further enhancing the polarity and hydrophilicity of F–FeWO4/NC. These changes favored the adsorption and desorption of intermediates as well as the diffusion of electrolyte, and ultimately reduced the ORR overpotential. Therefore, the F–FeWO4/NC catalyst demonstrated excellent ORR activity (E1/2 = 0.85 V vs. RHE). Furthermore, the ZAB with F–FeWO4/NC yielded satisfactory a specific capacity of 800.2 mAh g−1, a peak power density of 173.5 mW cm−2, and charge-discharge cycling stability (over 170 h at 5 mA cm−2). This study is beneficial to improve the ORR intrinsic activity of cheap tungsten-based materials and provides theoretical guidance for their practical application in ZABs.

Design of Efficient Oxygen Reduction Reaction Catalysts with Single Transition Metal Atom on N-Doped Graphdiyne.

The revelation of the underlying structure-property relationship of single-atom catalysts (SACs) is a fundamental issue in the oxygen reduction reaction (ORR). Here we present systematic theoretical and experimental investigations of various N-doped graphdiyne (NGDY) supported transition metals (TMs) to shed light on this relationship. Calculation results indicate that the TMs' comprehensive activities follow the order of Pd@NGDY > Ni@NGDY > Co@NGDY > Fe@NGDY, which fits well with our experimental conclusion. Moreover, detailed structure-property relationship (194 in total) analysis suggests that the key-species binding stability (ΔG*OH), the d-orbital center (εd/εd-a) and charge transfer (ΔQTM/ΔQTM-a) of the active metal before/after reactants adsorption and the bond length of TM-O (LTM-O) as descriptors can well reflect the intermediate binding stability or ORR activity on different TM-SACs. Specifically, the change trend of catalytic activity is opposite to that of intermediate binding stability, meaning that too strongly bonded *OOH, *O, and *OH intermediates are unfavorable for ORR.

A 3D Covalent Organic Framework with In-situ Formed Pd Nanoparticles for Efficient Electrochemical Oxygen Reduction.

Non-platinum noble metals are highly desirable for the development of highly active, stable oxygen reduction reaction (ORR) electrocatalysts for fuel cells and metal-air batteries. However, how to improve the utilization of non-platinum noble metals is an urgent issue. Herein, a highly efficient catalyst for ORR was prepared through homogeneous loading of Pd precursors by a domain-limited method in a three-dimensional covalent organic framework (COF) followed by pyrolysis. The morphology of the Pd nanoparticles (Pd NPs) was well maintained after carbonization, which was attributed to the rigid structure of the 3D COF. Thanks to the uniform distribution of Pd NPs in the carbon, the catalyst exhibited a remarkable half-wave potential of 0.906 V and a Tafel slope of 70 mV dec-1 in 0.1 M KOH, surpassing the commercial Pt/C catalyst (0.863 V and 75 mV dec-1 ). Furthermore, a maximum power density of 144.0 mW cm-2 was achieved at 252 mA cm-2 , which was significantly higher than the control battery (105.1 mW cm-2 ). This work not only provides a simple strategy for in-situ preparation of highly dispersible metal catalysts in COFs, but also offers new insights into the ORR electrocatalysis.

Solvent-free synthesis of ZrO2 nanoparticles/nitrogen-rich two-dimensional carbon nanosheet composites as efficient catalysts for ORR

An innovative, high-performance, non-noble-metal-based oxygen reduction reaction (ORR) catalyst must be developed utilizing a new and cost-effective technique. ZrO2 has the merits of high stability, low toxicity, good catalytic activity, and low enthalpy for atomic oxygen adsorption. However, the poor conductivity restricts its application as an ORR catalyst. Here, we successfully prepared ZrO2 nanoparticles / nitrogen-rich two-dimensional carbon nanosheet composites as ORR catalysts using a straightforward, solvent-free, one-step pyrolysis approach. Due to the unique component and structure characteristics, ZrO2@N-C-900 demonstrates remarkable ORR performances in alkaline electrolytes, such as high half-wave potential (0.82 V vs. RHE), higher current density (JL = 6.4 mA cm−2), and outstanding long term stability (95 % for 36,000 s). Especially, when used in a Zn-air battery, ZrO2@N-C-900 exhibited a power density of 148 mW cm−2, exceeding that of 20 % Pt/C.

Improvement of the electrocatalytic performance of silicon carbide for oxygen reduction reaction induced by nitrogen doping

Replacing the precious metal catalysts with low-cost, efficient and stable catalysts for oxygen reduction reaction (ORR) is necessary to solve the challenge of sluggish reaction kinetics. Commercial SiC and aniline were used as a precursor and nitrogen source to prepare a series of nitrogen-doped SiC electrocatalysts (N-SiC) by a facile pyrolysis method at different temperature (800–1100 °C) under nitrogen atmosphere. Among four N-SiC samples, N-SiC-1000 possesses the highest surface area, uniform nanorod morphology, highest nitrogen content, and positively shifted binding energy. Based on these characteristics, the N-SiC-1000 catalyst demonstrates the best ORR catalytic activity manifested by relatively positive onset potential of 1.01 V, half-wave potential (0.87 V) and highest current density (5.38 mA cm−2 at 0.4 V), which is comparable to that of Pt/C, and has significantly better stability and outstanding methanol tolerance than that of Pt/C. The number of electrons transferred of N-SiC-1000 for ORR process is ∼3.97, indicating a 4-electron reaction pathway. These results show that N-SiC-1000 is a low-cost, efficient and stable ORR catalyst and can be used as a substitute for precious metal catalyst in fuel cells application.

Modulating metal-support interaction between Pt3Ni and unsaturated WOx to selectively regulate the ORR performance

Tuning strong metal-support interaction between Pt-based alloys and metal oxides is an effective strategy for modulating the performance of oxygen reduction reaction (ORR). Herein, Pt3Ni alloy anchored on WOx with different content of oxygen vacancies is synthesized, and the effect of unsaturated WOx on ORR activity/stability is revealed. Electrochemical results indicate that ORR activity is positively correlated with oxygen vacancy concentration, while durability presents the opposite trend. Density functional theory (DFT) calculation results suggest that controlling the content of oxygen vacancies can usefully adjust the charge redistribution between Pt3Ni and WOx, which can optimize the adsorption/activation of reactants, thus obtaining good ORR activity. This study uncovers the effect of unsaturated WOx on ORR performance for Pt-based alloys and provides a promising strategy to design efficient and stable ORR catalysts.

Two-dimensional phthalocyanine-based covalent organic frameworks as high-performance electrocatalysts for oxygen reduction and oxygen evolution

It is crucial to use efficient catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in energy conversion devices, aiming to mitigate energy crises. The catalytic activity of MPc-PI-COF-1 and MPc-PI-COF-2 (M = Mn, Fe, Co) towards ORR and OER is investigated systematically based on DFT methods. Different M-N4 sites can adjust the binding strength of oxygen-containing intermediates to effect catalysis activity, while the different linkers have only a minor effect. FePc-PI-COF-1 and MnPc-based COFs have low ORR overpotential (ηORR) values, even lower than Pt(111). For OER, CoPc-based COFs have comparable OER overpotential (ηOER) values to that on RuO2(110). To sum up, MnPc-based COFs are efficient ORR catalysts, and CoPc-based COFs have high OER activity. FePc-PI-COF-1 could be served as an effective bifunctional catalyst with a ηORR value of 0.38 V and ηOER value of 0.56 V. Moreover, FePc-PI-COF-1 exhibits exceptional resistance to various impurity gases, indicating its strong tolerance against poisoning. These study offer valuable insights for the rational discovery of reticular materials as highly efficient electrocatalysts.

Atomically Dispersed Co2 MnN8 Triatomic Sites Anchored in N-Doped Carbon Enabling Efficient Oxygen Reduction Reaction.

Atomically dispersed transition metal-nitrogen/carbon (M-N/C) catalysts have emerged as the most promising substitutes to precious platinum counterparts toward oxygen reduction reaction (ORR). However, the reported M-N/C catalysts are usually in the form of common M-N4 moieties with only one single metal active site and suffer from insufficient activity. Herein, we elaborately developed an unusual trinuclear active structure with nitrogen-coordinated one Mn atom adjacent two Co atoms (Co2 MnN8 ) anchored in N-doped carbon as highly efficient ORR catalyst via adsorption-pyrolysis of bimetallic zeolitic imidazolate framework precursor. Atomic structural investigations and density functional theory (DFT) calculations revealed that Co2 MnN8 would experience a spontaneous OH binding to form Co2 MnN8 -2OH as the real active site, leading to a single electron-filled state in the orbital and an optimized binding energy of intermediates. Accordingly, the as-developed Co2 MnN8 /C exhibited an unprecedented ORR activity with a high half-wave potential of 0.912V and outstanding stability, not only surpassing the Pt/C catalyst but also representing a new record for the Co-based catalyst. This article is protected by copyright. All rights reserved.

A potentially efficient ORR catalyst: Transition metal-doped 2D Haeckelite MoS2

Enhancing the efficiency of the proton exchange membrane fuel cell (PEMFC) relies significantly on the development of low-cost but highly efficient catalysts for oxygen reduction reaction (ORR). In the present work, a specially structured two-dimensional layered material called Haeckelite (HL) MoS2 is investigated as an electrocatalyst for ORR by using density functional theory (DFT). In order to further improve the ORR catalytic performance, transition metals (TMs = Mn, Ru, Rh and Os) are independently doped on the surface of HL-MoS2. The detailed calculation includes the TMs doping, O2 molecule adsorption, electronic structure analysis, and Gibbs free energy comparison. The final results demonstrate that all TM/HL-MoS2 systems exhibit metallic properties, especially Ru/HL-MoS2 has the best catalytic performance for ORR in view of its moderate adsorption energy of O2 molecule (≈ 0.57 eV) and the lowest overpotential (≈ 0.503 V). Therefore, the combination of defect structure and TMs doping in MoS2 can be regarded as an effective approach to achieve both enhancement of catalytic performance and reduction of consumption of precious metals in the oxygen reduction reaction.

Hybridization of Carbon Nanotube Tissue, MnO2 Catalyst and CFx as an Advanced Air Cathode in Metal–Air Batteries

We first present the utilization of hybrid carbon nano-tube (CNT) – manganese dioxide (MnO2) tissues as air electrodes in nonaqueous aluminum- and lithium-based battery systems. The CNT tissues are impregnated with α-manganese dioxide nanoparticles via a straightforward binder-free ultrasonic treatment, thereby enabling an improved oxygen reduction reaction (ORR) catalytic activity. Half-cell potentiodynamic measurements along with full-cell discharge evaluations of Li- and Al-based battery systems are reported. Higher discharge potentials and capacities were obtained from generic and advanced hybrid CNT–MnO2 air cathodes. The discharge products obtained on the air cathode surface were studied using high-resolution scanning electron microscopy. Their chemical compositions were evaluated using elemental mapping energy-dispersive X-ray spectroscopy. The stability of the α-MnO2 catalyst was studied using X-ray photoelectron spectroscopy and electron paramagnetic resonance spectroscopy, thereby indicating the ongoing formation of an outer MnF2 shell layer, which affected the α-MnO2 functionality, as an efficient ORR catalyst. We conclude this part of the talk by showing that the function of the metal–air battery is enabled by using porous carbon nanotube (CNT)-based tissue substrates loaded with MnO2 catalyst.In contrast, fluorinated graphite (CFx) coating on the CNT substrate provides an additional discharge process, enhancing discharge capacity. Two CFx loadings are investigated, and their performances are compared with that of a pristine CNT tissue. Electrochemical evaluations, including half- and full-cell measurements, are performed to examine the effect of the coating layer thickness on the ability of the cell to function at high discharge rates.

Interface Engineering and Boron Modification of Pd-B/Pd Hetero-Metallene Synergistically Accelerate Oxygen Reduction Catalysis.

2D metallene possess high surface area and excellent electron transport capability, thus enabling efficient application in oxygen reduction reaction (ORR). However, the interface regulation and electronic structure optimization of metallene are still great challenges. Herein, Pd-B/Pd hetero-metallene is constructed by interface engineering and B modification strategies for efficient electrocatalytic ORR. The 2D configuration of Pd-B/Pd hetero-metallene exposes a large number of surface atoms and unsaturated defect sites, thus providing abundant catalytic active sites and exhibiting high electron mobility. More importantly, interface engineering and B modification synergistically optimizing the electronic configuration of the metallene system. This work not only provides an effective strategy for the rational regulation of the electronic configuration of metallene, but also offers a reference for the construction of efficient ORR catalysts.

Synergistic Catalysis of Cobalt Tetroxide and Bamboo-Shaped Carbon Nanotubes Doped with Nitrogen for Oxygen Reduction in Zn-Air Batteries.

Zinc-air batteries (ZABs) have been considered as one of the most emerging systems for energy conversion and storage. However, the preparation of highly efficient oxygen reduction reaction (ORR) catalysts on an air cathode is still faced with significant challenges. Herein, we report a secondary nitrogen source strategy for fine-tuning the active center, which provides a carbon-based hierarchical porous catalyst (termed Co3O4@N/CNT-1000) for highly efficient ORR activity (E1/2 = 0.87 V, JL = 5.32 mA cm-2, and Eonset = 1.021 V) and excellent stability. Controlled experiments demonstrate that such high activity derives from the synergistic effect of cobalt tetroxide and bamboo-shaped carbon nanotubes doped with nitrogen, prepared by the pyrolysis of a two-dimensional metal-organic framework nanosheet (termed NTU-70) and melamine. Furthermore, the ZAB assembled with Co3O4@N/CNT-1000 displays high specific capacity (854 mA h g-1Zn) and power density (179 mW cm-2), excellent long-term cycling (330 h), and durable charging/discharging ability.

Boosting activity on copper functionalized biomass graphene by coupling nanocrystalline Nb2O5 as impressive rate capability for supercapacitor and outstanding catalytic activity for oxygen reduction

A novel and hierarchical porous but cross-linked copper-doped biomass graphene (Cu@HPBG) combined with Nb2O5 (denoted as Nb2O5/Cu@HPBG) is successfully fabricated on a large-scale using fig peels as biomass carbon and copper as the graphitization catalyst. During the synthesis process, basic copper carbonate serves dual functions of pore-forming agent, as well as homogeneous copper provider, and NH3 is employed as a defect-forming agent and N dopant. Owing to the porous hierarchical structure increased availability of contact interface and pseudo capacitance active sites provided by copper and Nb2O5, the assembled asymmetrical supercapacitor (ASC) employing Nb2O5/Cu@HPBG as positive electrode and HPBG as negative electrode can not only widen the stability window range of 0～1.9 V, but also deliver a maximum gravimetric energy density of 82.8 W h kg−1 at the power density of 950.0 W kg−1 and maintain a remarkable cycling stability of 97.1% after 15,000 cycles. Impressively, due to the synergistic enhancement of Cu@HPBG and Nb2O5, the resulting Nb2O5/Cu@HPBG hybrid displays more positive half wave potential (∼0.85 V) and a long-life stability than Pt/C electrode toward oxygen reduction reaction (ORR). Our research provides a feasible strategy to fabricate renewable biomass graphene electroactive composites for large-scale supercapacitor electrodes and efficient ORR catalysts toward energy applications.

Spin state modulation on dual Fe center by adjacent Ni sites enabling the boosted activities and ultra-long stability in Zn-air batteries

Breakthrough in developing cost-effective Fe-based catalysts with superior oxygen reduction reaction (ORR) activities and ultra-long-term stability for application in Zn-air batteries (ZABs) remain a priority but still full of challenges. Herein, the neighboring NiN4 single-metal-atom and Fe2N5 dual-metal-atoms on the N-doped hollow carbon sphere (Fe/Ni-NHCS) were deliberately constructed as the efficient and robust ORR catalyst for ZABs. Both theory calculations and magnetic measurements demonstrate that the introduction of NiN4 provides a significant role on optimizing the electron spin state of Fe2N5 sites and reducing the energy barrier for the adsorption and conversion of the oxygen-containing intermediates, enabling the Fe/Ni-NHCS with excellent ORR performance and ultralow byproduct HO2− yield (0.5%). Impressively, the ZABs driven by Fe/Ni-NHCS exhibit unprecedented long-term rechargeable stability over 1200 h. This work paves a new venue to manipulate the spin state of active sites for simultaneously achieving superior catalytic activities and ultra-long-term stability in energy conversion technologies.

N-doped porous carbon encapsulated Fe and Ni bimetal derived from MOFs as efficient oxygen reduction reaction catalysts for anion exchange membrane fuel cell

The anion exchange membrane fuel cell (AEMFC) represents a promising avenue in clean energy equipment. However, its practical application is limited due to the high cost of Pt-based catalysts. Therefore, it is necessary to develop cheap and efficient non-precious metal catalysts. Here in, we employed a simple one-step thermal strategy to synthesize N-doped porous carbon encapsulated Fe and Ni bimetal catalysts (FeNi-N-C-1-1-Ts, T = 900, 950, 1000, 1050 and 1100 ℃). Among these catalysts, FeNi-N-C-1-1-1000 exhibited the highest half-wave potential of 0.885 V, 5 mV higher than 20 wt% Pt/C (0.880 V). Furthermore, it demonstrated a dominant 4e- reduction pathway, exceptional durability and high resistance to methanol. These excellent performances were attributed to the synergistic effect of FeNi bimetallicaction, increased graphitic content, higher Fe/Ni-N4 content, larger BET surface area and the presence of mesoporous structures. Moreover, FeNi-N-C-1-1-1000 exhibited higher half-wave potential than Ni-N-C-1000 and Fe-N-C-1000 owing to the smaller particle size and larger BET surface area of FeNi-N-C after the doping of Ni into Fe-N-C. Finally, FeNi-N-C-1-1-1000 was employed as the cathode in the AEMFC with a loading of 2.0 mg·cm−2, resulting in the highest peak power density of 545 mW·cm−2, surpassing that of 20 wt% Pt/C (375 mW·cm−2) by 170 mW·cm−2.