Enhanced Oxygen Evolution Reaction Performance Research Articles

Surface Reconstruction Regulation of Co3N Through Heterostructure Engineering Toward Efficient Oxygen Evolution Reaction.

Oxygen evolution reaction (OER) electrocatalysts generally experience structural and electronic modifications during electrocatalysis. This phenomenon, referred to as surface reconstruction, results in the formation of catalytically active species that act as real OER sites. Controlling surface reconstruction therefore is vital for enhancing the OER performance of electrocatalysts. In this study, a new approach is introduced of heterostructure engineering to facilitate the surface reconstruction of target catalysts. Using MnCo carbonate hydroxide (MnCo─CH)@Co3N as a demonstration, it is discovered that the surface reconstruction occurs more readily and rapidly on MnCo─CH@Co3N than on Co3N. More interestingly, during the reconstruction process, Mn species migrate to the surface, enabling the in situ formation of highly active Mn-doped CoOOH. Consequently, the MnCo─CH@Co3N catalyst after reconstruction exhibits a low overpotential of 257mV at 10mAcm-2, compared to 379mV of individual Co3N. This work offers fresh perspectives on understanding the enhanced OER performance of heterostructure electrocatalysts and the role of heterostructure in promoting surface reconstruction.

Facilitating the rapid Grotthuss diffusion of OH− in electrolyte for accelerated oxygen evolution reaction

Faster OH− transfer for efficient adsorption on catalysis is key to accelerating the oxygen evolution reaction (OER). The diffusion of OH− in electrolyte mainly involves two mechanism which is dependent on the water coordination number (CN): Grotthuss diffusion (4 CN) and vehicular diffusion (5 CN). The Grotthuss diffusion is much faster but the vehicular diffusion of OH− is predominant in the electrolyte. Herein, negatively charged kaolin, which are simply dispersed in the electrolyte, are utilized to provide surface electrostatic attraction to H2O and repulsion to OH− to reduce the OH− CN from 5 to 4 for rapid Grotthuss diffusion. This contributes to the accelerated OH− adsorption which facilitates the charge transfer, the formation and the deprotonation of *OOH leading to enhanced OER performance. The OH− CN recovery from 4 to 5 is proved quite slow after leaving the kaolin surface, breaking the limitation that kaolin must be on the catalyst surface. This strategy exhibits universality for various electrocatalysts with reduced overpotential by 10–246 mV at 10 mA cm−2. We provide a clean, simple and low-cost way to promote the industrial development of alkaline water electrolysis.

Investigating the Role of Mixed Oxides for Oxygen Evolution Reaction on Iridium Oxide Electrocatalysts

Ongoing concerns over anthropogenic emissions, fossil fuel sustainability, and related geopolitical aspects point to an increasing need for cost-effective renewable fuel sources. A promising solution is the generation of hydrogen via the catalytic splitting of water, which can be achieved with the aid of proton exchange membrane (PEM) electrolyzers. Notably, the anode material in current commercially available PEM electrolyzers is typically iridium oxide. Despite its effectiveness in facilitating the oxygen evolution reaction (OER), the use of iridium oxide poses challenges due to the scarcity and high cost associated with this precious metal. As the quest for sustainable energy intensifies, ongoing research explores innovative approaches, such as the incorporation of alternative materials and catalysts, to enhance efficiency while addressing the economic and environmental concerns associated with iridium oxide. Studies have shown that incorporating mixed oxides and switching the supports for iridium oxide catalysts help lower the iridium loading while enhancing the OER performance.1,2 In this study, we investigate a series of different sputtered, mixed iridium oxides (Ta, Ti, Ir). We use a rotating disk electrode system to benchmark the catalytic activity of different loadings of mixed oxides. To measure the intrinsic activity of each catalytic active site, we use a home-built operando UV-Vis system to quantify the populations of surface species as well as track the kinetics of different redox transitions during OER. We incorporate nanoscale secondary ion mass spectrometry to probe the migration of different mixed oxide species before and after electrochemical cycling and use kelvin probe force microscopy to estimate the conductivity through the different films. In this study, we show the importance of cooperative effects between neighboring iridium oxide species and the coordination of iridium that are responsible for enhanced OER performance. These results indicate that doping modulates coverage dependent interactions at the surface, which affects both the binding energetics and populations of rate limiting intermediates. We believe this study will serve as a steppingstone for future designs of more cost-efficient PEM electrolyzers.(1) Oh, Hyung-Suk, et al. "Electrochemical catalyst–support effects and their stabilizing role for IrO x nanoparticle catalysts during the oxygen evolution reaction." Journal of the American Chemical Society 138.38 (2016): 12552-12563.(2) Zheng, Ya-Rong, et al. "Monitoring oxygen production on mass-selected iridium–tantalum oxide electrocatalysts." Nature Energy 7.1 (2022): 55-64.

Photoluminescence, cytotoxic and oxygen evolution reaction kinetics studies of silver doped haematite nanoparticles

Fe2O3: Ag(1–9 mol %) nanoparticles (NPs) have been synthesized through the co-precipitation method. Crystallite size, phase, crystallinity, and structural parameters were analyzed by using powder X-ray diffraction. The Bragg reflections confirm that the synthesized NPs crystallize in hexagonal crystal structure with space group R-3c. Surface morphology consists of agglomerated irregular size and roughly spherical-shaped NPs. Energy Dispersive Analysis of X-ray confirms the presence of Fe, O, and Ag elements and also the purity of the sample. Crystallite size decreased with the increase in dopant concentration. Direct band gap energy is found to increase with an increase in dopant concentration. Photoluminescence and anticancer properties were studied in detail. The CIE coordinates confirm red emission in the visible region. CIE and CCT co-ordinate values indicate cool light emission, hence, the synthesized nanophosphor material meets the demand of display technology. Further anticancer properties were investigated on HeLa cells and compared with the standard drug cisplatin for biomedical applications. Further, Oxygen evolution reaction kinetics was investigated for Fe2O3:Ag (1 mol %) nanoparticles. demonstrates enhanced oxygen evolution reaction performance with a low overpotential of 348 mV, as shown by linear sweep voltammetry. It also exhibits a favorable Tafel slope of 83 mV/dec, indicating efficient electron transfer kinetics, making it a promising candidate for OER applications.

Magnesium-promoted rapid self-reconstruction of NiFe-based electrocatalysts toward efficient oxygen evolution

The acceleration of active sites formation through surface reconstruction is widely acknowledged as the crucial factor in developing high-performance oxygen evolution reaction (OER) catalysts for water splitting. Herein, a simple one-step corrosion method and magnesium (Mg)-promoted strategy are reported to develop the NiFe-based catalyst with enhanced OER performance. The Mg is introduced in NiFe materials to preparate a “pre-catalyst” Mg-Ni/Fe2O3. In-situ Raman shows that Mg doping would accelerate the self-reconstruction of Ni/Fe2O3 to form active NiOOH species during OER. In-situ infrared indicates that Mg doping benefits the formation of *OOH intermediate. Theoretical analysis further confirms that Mg doping can optimize the adsorption of oxygen intermediates, accelerating the OER kinetics. Accordingly, the Mg-Ni/Fe2O3 catalyst exhibits excellent OER performance with overpotential of 168 mV at 10 mA cm−2. The anion exchange membrane water electrolyzer achieved 200 mA cm−2 at voltage of 1.53 V, showing excellent stability over 500 h as well. This work demonstrates the potential of Mg-promoted strategy in regulating the activity of transition metal-based OER electrocatalysts.

Promoted surface reconstruction of pentlandite via phosphorus-doping for enhanced oxygen evolution reaction

The pentlandite Fe5Ni4S8(abbreviated as FNS) is not efficient for water splitting because of its inferior performance for the oxygen evolution reaction (OER). This issue originates from the low activity and instability of FNS during the OER process but can be solved through appropriate doping. Herein, a P-doping strategy based on annealing in the presence of NaH2PO2as a phosphorus source upstream was employed on FNS to enhance its activity and stability toward OER. The results demonstrated fine-tuned electronic structures of Fe and Ni in FNS through P-doping, resulting in suppressed Fe leaching,improved electrical conductivity of FNS, and easier formation of NiOOH on the surface of the catalyst. In turn, these features enhanced the OER activity and stability. The optimal P-doped FNS catalyst FNSP-40 exhibited a 4-fold greater electrochemical surface area compared to that of FNS, accompanied by an overpotential of 235 mV at 10 mA cm−2. The optimized FNSP-40 catalyst was used as an anode, and platinum-decorated FNS was used as a cathode. This combination demonstrated an electrolysis performance with a cell voltage of 1.57 V, reaching a current density of 100 mA cm−2,which indicates efficient operation. The advantages of P-doping engineering were also verified in simulated seawater with enhanced OER performance. Overall, the proposed strategy looks promising for the fabrication of pentlandite-structured catalysts for efficient alkaline water and seawater oxidation.

Enhanced Oxygen Evolution Reaction Performance in Co–Fe Hydroxides through Boron Doping

Among hydrogen production methods, water electrolysis stands out, but its efficiency is hampered by the substantial energy barrier of the oxygen evolution reaction (OER). To address this, incorporating electron‐deficient boron (B) into Co–Fe hydroxide (CoFeOxHy) promotes higher oxidation states of involved metals, greatly enhancing OER activity and charge transfer capabilities. Herein, the synthesis of a range of amorphous CoFeB nanoparticles with varying Fe to (Co+Fe) atomic ratios achieved through a simple chemical reduction method using CoFe‐Prussian blue analogs as precursors and employing Mössbauer spectroscopy to observe structural characteristics before and after transformation is reported. Among these nanoparticles, the CoFe0.25B variant, exhibiting favorable electrochemical properties, is chosen and subsequently subjected to hydrolysis to yield CoFe0.25BOH nanoparticles, serving as an active catalyst for OER. At a current density of 10 mA cm−2, the overpotentials for CoFe0.25OxHy and CoFe0.25BOH are 362 and 310 mV, respectively, with Tafel slopes decreasing from 393 to 93 mV dec−1. Furthermore, the i–t test reveals no significant loss of electrochemical performance within 24 h, substantiating the efficacy of enhancing the electrocatalytic performance of CoFeOxHy through the introduction of electron‐deficient elements. This research offers novel insights into the development of efficient and stable water electrolysis catalysts.

Enhanced oxygen evolution reaction performance of nitrogen-doped carbon dots sensitized with rare-earth metal nanorods

An affordable, sustainable, effective, and strong catalyst for oxygen evolution reaction (OER) processes has gained increased significance because of its crucial role in energy conversion and storage. Heteroatom-doped amorphous carbon materials made from biomass have lately come into prominence as inexpensive, environmentally benign, renewable, and sustainable materials. Substantial research about the incredible performance in OER by carbon dots has been devoted, yet durability remains a challenge. Therefore, we reported novel carbon dots doped with a heteroatom (nCDs) included with Gd(OH)3, a rare-earth hydroxide element. Taking advantage of numerous active and edge sites of CDs and modifying the chemistry of the surface by doping with foreign atoms, the prepared nCDs/Gd(OH)3 revealed the outstanding catalytic performance of a low overpotential of 280 mV at a Tafel slope of 127 mV/dec at 10 mA/cm2 in sluggish alkaline medium. Our findings supported the synergistic interaction between the doped heteroatom and its surface's maximal exposure of nCDs/Gd(OH)3 sites, facilitating the rapid transport of reactants and sufficient contact to enhance OER performance. This study will garner more attention in the context of producing sustainable energy and storing it effectively. For clean, green energy, combining carbon dots with rare earth metals is an emerging candidate for energy conversion. The alkaline electrolyzer will find it to be a promising electrocatalyst, especially in seawater medium.

Electronic structure tailoring of CuCo2O4 for boosting oxygen evolution reaction

Electronic structure tuning in metal oxides is a facile and effective strategy on boosting their catalytic oxygen evolution reaction (OER) performance. Here, we demonstrate the electronic structure tuning of CuCo2O4 by phosphorus (P) doping via in-situ diffusion method. The results suggest that due to more electrons transferred from P to the neighboring Co3+, the tuned Co is served as catalytic active sites for the enhanced OER performance. The synthesized P3.85-CCO/NF exhibits an overpotential of 250 mV at a current density of 10 mA cm−2, and a Tafel slope of 27 mV dec−1, which performs an enhanced OER activity than that of IrO2/NF. Moreover, the P3.85-CCO/NF presents stable electrochemical performances upon long-time running for 30 h. Thus, the electronic structure tuning strategy by in-situ P diffusion method emerges as an effective approach on enhancing the catalytic OER performance for metal oxide electrocatalysts.

Ce- and La-doped polymetallic layered double hydroxides for enhanced oxygen evolution reaction performance at high current density

Ce- and La-doped polymetallic layered double hydroxides for enhanced oxygen evolution reaction performance at high current density

Atomic rare earths activate direct O-O coupling in manganese oxide towards electrocatalytic oxygen evolution

Activating the efficient electron transfer in oxygen evolution reaction (OER) by tuning the oxygen (O) electronic states near the Fermi level is essential to break the linear scaling limitation of OER intermediates. Herein, we construct a series of rare earth (RE) single atoms on MnO2 nanosheets with modulated oxygen states by an effective and universal Ar plasma (P)-assisted strategy (P-RE SAs@MnO2, RE = Gd, La, Ce, Tm, and Lu) to investigate the origin of RE-enhanced OER performance. Taking P-Gd SAs@MnO2 as a representative, the atomically dispersed Gd atoms on MnO2 assist the construction of localized asymmetric [Gd−O−Mn] units, which induces electron accumulation at surrounding oxygen sites by introducing the polarized ionic Gd−O bond. As a result, the P-Gd SAs@MnO2 delivers impressive OER performance with low overpotential (281 mV@10 mA cm −2; ηj10), robust long-term stability, and optimized activation energy (Ea = 32.07 kJ mol−1 at ηj10), which are superior to RE-free MnO2, commercial RuO2, and most Mn-based catalysts. Similar enhanced OER performance can also be found for other P-RE SAs@MnO2 (RE = La, Ce, Tm, and Lu). X-ray absorption and in situ Raman spectroscopy unveil the preferred electron accumulation at Mn−O, promoting the formation of terminal MnIV=O intermediates in OER. Theoretical calculations demonstrate that the construction of [Gd−O−Mn] unit endows the surface lattice unsaturated O site with the labile property, which assists the direct formation of (O−O) dimer for circumventing the universal scaling relation applied by the formation of *OOH. This work opens up a new avenue for the design of transition metal oxides with modulated oxygen state to break the limitation of the adsorbate evolution mechanism during OER.

Iron-Nickel synergistic catalysis growth of (Fe,Ni)9S8/Ni3S2@N,S codoped carbon bridged nanowires enhanced oxygen evolution reaction performance

Improving the conductivity of the electrocatalyst itself is essential for enhancing its performance. In this work, N, S-rich 6-thioguanine (TG) is selected as the ligand to synthesize a Fe, Ni bimetallic porous coordination polymer (PCP), which is then derived to fabricate N,S codoped carbon (NSC)-coated (Fe,Ni)9S8/Ni3S2 bridged nanowires. The (Fe,Ni)9S8/Ni3S2@NSC bridged nanowires obtained through bimetallic synergistic catalysis and self-sulfurization processes not only introduced additional electrocatalytic active sites but also significantly enhance the overall conductivity of the catalyst due to the interconnected nanowire structure. The resulting (Fe,Ni)9S8/Ni3S2@NSC demonstrates remarkable oxygen evolution reaction (OER) performance, exhibiting an overpotential as low as 252 mV at a current density of 10 mA cm−2. This work proposes a novel strategy for enhancing the overall conductivity of catalysts by growing bridged nanowires, providing valuable insights and inspiration for the design and preparation of advanced transition metal sulfide electrocatalysts.

Novel amorphous FeOOH-modified Co9S8 nanosheets with enhanced catalytic activity in oxygen evolution reaction

Efficient oxygen evolution reaction (OER) is vital for water electrolysis and advanced hydrogen energy production. However, the sluggish kinetics of this reaction require significant overpotentials, leading to high energy consumption. Therefore, developing OER electrocatalysts with exceptional performance and long-term durability is crucial for enhancing the energy efficiency and cost-effectiveness of the hydrogen production process. In this research, novel FeOOH/Co9S8 catalysts were prepared through a two-step hydrothermal reaction followed by one-step electrodeposition on nickel foam for an alkaline OER. The as-obtained catalysts possessed abundant non-homogeneous interfaces between FeOOH and Co9S8 nanosheets, conducive to optimized coordination environments of Fe and Co sites by redistributing interfacial charges. This synergy strengthened the chemisorption of oxygenated intermediates, leading to accelerated reaction kinetics, abundant active sites, and enhanced OER performance. The optimized electrocatalyst FeOOH/Co9S8-15 achieved a current density of 10 mA cm-2 at an overpotential of 248 mV and good stability for over 140 h. This study presents a novel approach for producing compelling and durable alkaline dielectric OER electrocatalysts, which will be helpful in the future manufacturing of advanced energy devices.

A Bifunctional Electrocatalyst of Flower-Like Cr-Doped CoP/Fe2P Microsphere for Efficient Overall Water Splitting

Developing efficient, low-price non-noble metal-based electrocatalysts for overall water splitting in alkaline medium remains a formidable challenge. In our work, Cr-doped CoP/Fe2P (Cr-CoP/Fe2P) flower-like microsphere was synthesized through a simple hydrothermal and phosphating process. The resulting Cr-CoP/Fe2P electrocatalyst shows significantly enhanced oxygen evolution reaction performance (262 mV @ 10 mA cm−2) and has a satisfactory hydrogen evolution reaction performance (114 mV @ 10 mA cm−2), coupled with favorable stability in an alkaline medium. Furthermore, when assembling Cr-CoP/Fe2P into an electrolytic cell, the two-electrode system can provide a current density of 10 mA cm−2 at a voltage of 1.61 V. At high current density, the performance of the electrolytic cell composed of Cr-CoP/Fe2P is superior to that of noble metal catalyst electrode pair. Electronic structure analysis and various characterizations confirm that Cr doping and the formation of CoP/Fe2P heterogeneous interfaces redistribute the electron densities of the active sites, enlarge the specific surface area, and enhance the aerophobicity of the catalysts, thereby improving the electrocatalytic property. This work provides a referable method for engineering highly efficient and stable non-noble polymetallic phosphides, which serve as bifunctional electrocatalyst for overall water splitting.

Tailoring hypervalent Nickel induced by oxygen vacancy toward enhanced oxygen evolution reaction performance in self-supporting NiFe-(oxy)hydroxides electrodes

NiFe-(oxy)hydroxides are the most active transition metal oxide electrocatalysts for oxygen evolution reaction (OER) under the alkaline media. Herein, we controllably manipulated oxygen vacancy (VO)-tunable NiFe-(oxy) hydroxides that their OER performances possessed a volcano-type relationship with VO concentration, positively-correlated with Ni3+/Ni2+ ratio. Theoretical simulations further unearthed the enhanced activation and dissociation of H2O by the inserting of VO. As a result, the optimal sample featuring the Ni3+/Ni2+ ratio of 30.3 % and VO of 23.8 % exhibited the overpotential of 243 mV at the current density of 100 mA cm–2, simultaneously lasting 120 h durability without any attenuation, exceding the most reported NiFe-(oxy)hydroxides. This work offers an innovative view to understand the OER performance using hypervalent Ni ratio induced by VO defects.

Rapid Construction of Double Crystalline Prussian Blue Analogue Hetero-Superstructure.

The controllable construction of complex metal-organic coordination polymers (CPs) merits untold scientific and technological potential, yet remains a grand challenge of one-step construction and modulating simultaneously valence states of metals and topological morphology. Here, a thiocyanuric acid (TCA)-triggered strategy is presented to one-step rapid synthesis a double-crystalline Prussian blue analogue hetero-superstructure (PBA-hs) that comprises a Co3[Fe(CN)6]2 cube overcoated with a KCo[Fe(CN)6] shell, followed by eight self-assembled small cubes on vertices. Unlike common directing surfactants, TCA not only acts as a trigger for the fast growth of KCo[Fe(CN)6] on the Co3[Fe(CN)6]2 phase resulting in a PBA-on-PBA hetero-superstructure, but also serves as a flange-like bridge between them. By combining experiments with simulations, a deprotonation-induced electron transfer (DIET) mechanism is proposed for formation of second phase in PBA-hs, differing from thermally and photo-induced electron transfer processes. To prove utility, the calcined PBA-hs exhibits enhanced oxygen evolution reaction performance. This work provides a new method to design of novel CPs for enriching chemistry and material science. This work offers a practical approach to design novel CPs for enriching chemistry and material science.

Unlocking the potential of Heusler alloy Ni2CuSn as an electro(pre)catalyst for enhanced oxygen evolution reaction performance

Unlocking the potential of Heusler alloy Ni2CuSn as an electro(pre)catalyst for enhanced oxygen evolution reaction performance

Customized structure engineering of MIL-53(Fe)/MoS2/NF for enhanced OER performance: Experiments and practical applications

Developing cost-effective and highly efficient catalysts to replace the expensive noble metal-based counterparts in the oxygen evolution reaction (OER) holds paramount importance for the advancement of hydrogen production. Herein, we synthesized a novel hybrid composite of MIL-53(Fe) and MoS2 using a hydrothermal method, subsequently depositing it onto commercially available nickel foam (NF), namely MIL-53(Fe)/MoS2/NF. The MIL-53(Fe)/MoS2/NF composite capitalizes on the synergies among these three components, facilitating efficient water electrolysis while remarkably curbing the OER overpotential (η10 = 238 mV, 1 M KOH), thereby enhancing electron transport efficiency. Remarkably, the OER overpotential remains consistently low even in the prepared 1 M KOH solution using seawater (η10 = 289 mV) and sewage (η10 = 301 mV). Moreover, MIL-53(Fe)/MoS2/NF exhibits enduring stability, maintaining its efficacy even after 50 h at around 50 mA/cm2 in simulated solutions, sewage, and seawater. In an electrolytic cell utilizing MIL-53(Fe)/MoS2/NF as the anode, stable gas production is achieved under 1 M KOH conditions and solar cell voltages of 1.62 V and 1.85 V. This investigation marks a pivotal advancement in forging highly efficient and economically viable OER catalysts, holding substantial implications for advancing energy conversion methodologies, thereby ushering in escalated efficiency and diminished costs.

Supramolecular Macrocycle Regulated Single‐Atom MoS2@Co Catalysts for Enhanced Oxygen Evolution Reaction

The development of active water oxidation catalysts for water splitting has stimulated considerable interest. Herein, the design and building of single atom Co sites using a supramolecular tailoring strategy are reported, that is, the introduction of pillar[4]arene[1]quinone (P4A1Q) permits mononuclear Co species stereoelectronically assembled on MoS2 matrix to construct an atomically dispersed MoS2@Co catalyst with modulated local electronic structure, definite chemical environment and enhanced oxygen evolution reaction performance. Theoretical calculations indicate that immsobilized single‐Co sites exhibit an optimized adsorption capability of oxygen‐containing intermediates, endowing the catalyst an excellent electrocatalytic oxygen evolution reaction activity, with a low overpotential of 370 mV at 10 mA cm−2 and a small Tafel slope of 90 mV dec−1. The extendable potential of this strategy to other electrocatalysts such as MoS2@Ni and MoS2@Zn, and other applications such as the hydrogen evolution reaction was also demonstrated. This study affords new insights into the rational design of single metal atom systems with enhanced electrocatalytic performance.

Pre-implanting metal oxides to endow the N-doped carbon with boosted bifunctional catalytic activities towards oxygen reduction and oxygen evolution reactions

Nitrogen-doped carbon-based materials exhibit promising prospect as the catalysts to oxygen reduction reaction (ORR). Incorporating transition metal oxides with the catalysts can endow them with oxygen evolution reaction (OER) activity to construct bifunctional catalysts for rechargeable zinc-air batteries. In this work, a catalyst (named as 300NiFe-Mi-C) was prepared by a metal oxide-implanting strategy. The mixed metal salts of Ni and Fe were first heated to produce metal oxides, and then blended with 2-methylimidazole and carbon black, and subsequently pyrolyzed at a high temperature. In the pyrolysis, a part of metal oxides was reduced to metallic state to facilitate the doping of nitrogen atoms into carbon to form the ORR active sites while a part of metal oxides was retained to afford OER activity. Benefiting from the pre-implanting strategy of metal oxides, the resultant 300NiFe-Mi-C presents enhanced OER performance with 1.56 V of OER potential at 10 mA cm−2, outperforming the 1.68 V of the controlled sample NiFe-Mi-C (without pre-implanting) and 1.70 V of RuO2. The 0.83 V of ORR half-wave potential of 300NiFe-Mi-C is also comparable to the 0.82 V of NiFe-Mi-C and 0.86 V of Pt/C, revealing satisfactory bifunctional catalytic activities. The rechargeable zinc-air battery equipped with 300NiFe-Mi-C can stably operate at ∼1.25 V with 10 mA cm−2, being higher than ∼1.21 V of Pt/C+RuO2. The battery also presents outstanding durability and rechargeability, demonstrating the bifunctional activities of 300NiFe-Mi-C can be realized in practical applications.