Peroxide Yield Research Articles

High yield of hydrogen peroxide on modified graphite felt electrode with nitrogen-doped porous carbon carbonized by zeolitic imidazolate framework-8 (ZIF-8) nanocrystals

The aim of this work was to develop a new modified graphite felt (GF) as carbonaceous cathode for electro-Fenton (EF) application loaded with nitrogen-doped porous carbon (NPC) carbonized by zeolitic imidazolate framework-8 (ZIF-8) nanocrystals as carbon precursor. At initial pH 7, the highest generation rate of H2O2 was 0.74 mg h−1 cm−2 by applying 12.5 mA cm−2 by modified cathode, but in the same condition, the GF only had 0.067 mg h−1 cm−2. The production efficiency increased 10 times. Additionally, phenol (50 mg L−1) could be largely removed by NPC modified cathode, the mineralization ratio and TOC reached 100% and 82.61% at 120 min of optimization condition, respectively. The NPC cathode kept its stability after 5 cycles. The materials were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and linear sweep voltammetry (LSV). The results demonstrated that a homogenous NPC covered the carbon-based material GF. The existing graphitic-N and sp2 carbon of NPC promoted the electron transfer between carbon surface and oxygen molecules, as well as accelerated the oxygen reduction reaction (ORR) and the modified graphite felt had much higher electrocatalytic activity. In this work, several manufacturing parameters like the current, pH and load of NPC were optimized. The optimized design could improve the efficiency of new cathode with in situ electro-chemical production of H2O2 and significantly offer a potential material for degradation of organic pollutants.

Oxidation-reduction potential (ORP) as a tool for process monitoring of H2O2/LPMO assisted enzymatic hydrolysis of cellulose

Abstract Oxidation-reduction potential (ORP) is an environmental factor of importance in several biological conversion processes. Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative disruption of the cellulose chain in the presence of oxygen or hydrogen peroxide and increase enzymatic hydrolysis yields. However, the enzymes are also sensitive to oxidative damage and the level of oxidative agent needs to be controlled to avoid inactivation of the LPMOs. In the current study, enzymatic hydrolysis of sulfite-pretreated softwood (12% DM loading) was carried out in lab scale reactors with gradual addition of hydrogen peroxide using an LPMO-containing commercial enzyme cocktail. The ORP was measured during enzymatic hydrolysis together with released glucose and the level of C4-oxidized dimer as a marker for LPMO activity. Arrests in LPMO activity coincided with a markedly changed ORP signal and this was utilized in subsequent experiments in which the feed rate of hydrogen peroxide was controlled by keeping the ORP at predetermined set-points of -40 mV, -80 mV and -120 mV. Under anaerobic conditions, the highest hydrolysis yield (78% after 72 h) was found for the ORP set-point of -80 mV. The results show that ORP can serve as an indicator of LPMO activity and may help optimizing overall process efficiency.

Ethanol-controlled peroxidation in liquid-anode discharges

Discharge plasma–liquid systems provide an interesting research field for many physical and chemical processes. These fascinating processes can be studied by using systems with liquid as anode and cathode, and the yield of aqueous hydrogen peroxide (H2O2aq) in the plasma–liquid system with the liquid anode is significantly lower than that with the liquid cathode. We improve the H2O2aq yield in the plasma–liquid system with the liquid anode by adding appropriate amount of ethanol in the liquid. A seven-time increase in the production rate is reached when the ethanol volume concentration is 5%, while further increase in the ethanol concentration will decrease the production rate. The H2O2aq production improvement is ascribed to the atomic oxygen-induced hydrogen abstraction reactions from ethanol which in situ improve the concentration of the H2O2 building brick, the OH radicals, in the liquid. However, excessive ethanol can scavenge the in situ formed OH radicals through the hydrogen abstraction reaction, by which the H2O2aq formation is inhibited.

Efficient oxygen electroreduction kinetics by titanium carbide@nitrogen doped carbon nanocomposite

A simple approach towards preparation of non-noble metal electrocatalyst for oxygen reduction reaction in low temperature fuel cells has been necessity for a sustainable green technology. Herein, a cost-effective and facile method of preparation of TiC@N-doped graphene like carbon nanocomposite (TiC@NC) has been discussed. The composite structure of as-prepared TiC@NC was confirmed using structural analysis and morphological studies. Interestingly, the optimized TiC@NC(0.2)-800 electrocatalyst shows remarkable oxygen reduction reaction (ORR) kinetics with better onset potential +1.08 vs RHE and significant current density of 4.8 mA/cm2 in alkaline medium. Further, obtained catalyst exhibits four electron transfer mechanism similar to Pt-based electrocatalysts. Additionally, TiC@NC(0.2)-800 shows better mass activity (∼410 mA/mg) as compared to other compositions. Moreover, the single step kinetics mechanism has been seen due to lower (<5%) peroxide yield. The relatively lower charge transfer resistance at electrode/electrolyte interface of TiC@NC (0.2)-800 electrode supports for higher catalytic activity. Additionally, electrochemical cycling reveals the better stability by TiC@NC(0.2)-800 even after 10,000 cycles (10 mV negative shift in E1/2) than that of state of art Pt/C catalyst (80 mV negative shift in E1/2). The presence of N-doped carbon around TiC crystals is responsible for better electrocatalytic activity (due to optimal doping synergy), though the support of TiC makes the electrocatalyst more stable in nature (thanks to strong TiC-NC interactions). Additionally, TiC@NC(0.2)-800 does not show any response towards methanol oxidation reaction, annulling the cross-over effects. Hence, TiC@NC(0.2)-800 could be hopeful substitute for conventional Pt/C electrocatalyst for energy conversion.

Alpha radiolysis of DOTA ligand in aqueous solutions with helium ion beams

Samples of DOTA (1,4,7,10-tetraazacyclodécanetetraacetic acid) ligand in aqueous solutions have been irradiated with helium ion (4He2+) beams of the ARRONAX (Nantes) and CEMHTI (Orléans) cyclotrons. Formation yields of gaseous radiolysis products (H2, CO2 …) have been measured by micro-gas chromatography. Yield of hydrogen peroxide has in turn been determined by colorimetric titration with titanium (IV). Degraded solutions were also analyzed by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectroscopy (NMR) in order to identify degradation products formed after irradiation and quantify the non-degraded DOTA ligand. Results showed that the presence of DOTA in water leads to an increase of G(H2) and a decrease of G(H2O2). A degradation scheme is proposed: DOTA is degraded through decarboxylation, losing CO2 moieties, condensation of two carboxylic acid moieties with elimination of either a carbonic acid or a glycolic acid group, cleavage of -CH2-COOH, N-CH2-COOH and (CH2-CH2)N-CH2-COOH fragments, or by recombination with a hydroxyl radical (OH). NMR analyses showed that almost a third of DOTA ligand was degraded after 110 kGy alpha irradiation dose.

Improving the yield of hydrogen peroxide on gas diffusion electrode modified with tert-butyl-anthraquinone on different carbon support

Hydrogen peroxide (H2O2) is a green oxidant that widely used in environmental remediation and chemical industries, hence the exploration of suitable modified cathode for the cost-effective electrochemical synthesis of H2O2 is of great importance. In this work, tert-butyl-anthraquinone (TBAQ) was attempted to modify four kinds of typical carbon materials (carbon aerogel, carbon nanotube (CNT), carbon black and graphene-doped carbon black) to fabricate gas diffusion electrode (GDE) to improve H2O2 production for potential use in electro-Fenton process. It was found that CNT-GDE containing 2% TBAQ had the highest H2O2 production (150.6 mg/L) with a high current efficiency (95%) and low energy consumption (2.43 kWh/(kg H2O2)) among four carbon materials because of the redox of TBAQ and more active sites (C–C sp3 carbon and oxygen-containing functional groups). The effects of TBAQ addition amount, current and initial pH on H2O2 performance were investigated. The presence of TBAQ could improve oxygen reduction activity, H2O2 selectivity and hydrophobicity to improve H2O2 production. Suitable current (50 mA) and initial pH benefited the enhancement in H2O2 production. The CNT-GDE containing 2% TBAQ showed better H2O2 production performance with good stability when comparing with literature, indicating promising for electro-Fenton application.

Electroreduction of oxygen on Nafion®-coated thin platinum films in acid media

Electrocatalytic oxygen reduction reaction (ORR) kinetics on vacuum-evaporated thin platinum films in sulfuric acid solution is thoroughly investigated employing the rotating disc electrode (RDE) method. The nominal thickness of the Pt films is varied from 0.25 to 20nm and the effect of applied Nafion® layer on the ORR activity in 0.5M H2SO4 solution is evaluated. The electroactive surface area of Pt and the corresponding overall ORR activity decreases with the nominal film thickness. An increase in the hydrogen peroxide yield and a decrease of the ORR specific activity of Pt with decreasing the film thickness is also observed. The Nafion® coating slightly increases the hydrogen peroxide production, but does not affect the electrocatalytic activity of Pt. The results obtained with the model system employed herein are important for elucidating the influence of Nafion® layer on the ORR kinetics on Pt-based electrocatalysts.

Designed self-assembly of iron encapsulated doped porous carbon as durable electrocatalyst for oxygen reduction reaction in alkaline medium

A probable pore-formation mechanism of self-assembled doped porous carbon has been proposed. Hydrogen-bonding interaction between different precursors plays a crucial role in determining the porous morphology. The high specific surface area of porous carbon network consists of an abundant number of mesopores as well as micropores which promote the enhanced diffusion of ions and further reduce the mass transfer losses by increasing the number of triple phase boundaries (TPBs). Encapsulation of iron particles within the porous framework not only preserves the intrinsic catalytic properties of the metal also enhances the durability of the catalyst. Iron incorporation in nitrogen (N), boron (B) and co-doped porous carbon predominantly improves the reaction kinetics compared to metal-free catalysts in terms of onset potential and current density. Iron incorporated N and B co-doped porous carbon (Fe/NBPC) has exhibited an onset potential of −0.12 V vs SCE with low peroxide yield of 12%. Comprehensive theoretical analysis based on net charge transfer and total density of states reveal the superiority of co-doping. Present work validates multi-element doped carbon network can be considered as a promising replacement of Pt-based catalysts for fuel cells in alkaline medium.

Enhancing the yield of H2O2 from oxygen reduction reaction performance by hierarchically porous carbon modified active carbon fiber as an effective cathode used in electro-Fenton

The aim of this work was to study a new type of high efficiency cathode material using hierarchically porous carbon (HPC) to modify activated carbon fibers. Compared to the cathode prior to modification, the H2O2 output (up to 9.9mgL−1) showed an increase, and the energy consumption (8.9 kWh kg−1) was reduced. Since it is a thin layer sheet, the synthesized HPC had many carbon particles, a high surface area, and the oxygen reduction reaction had a much higher electrocatalytic activity. In addition, the material also has a good content of sp3-C, defects, and fast mass transfer. These characteristics promoted the production of H2O2 when using the optimal proportion of HPC, and electricity generation of hydrogen peroxide showed a tenfold improvement. Additionally, after being reused 5 times, the modified cathode still demonstrated stable performance. A series of characterization analyses to further demonstrate the superiority of this electrode found that the presence of HPC accelerates the electron transfer rate and facilitates oxygen reduction reactions (ORRs) on the electrode surface. When this cathode is used in an electro-Fenton system, phenol can be almost completely degraded, and up to 93.8% of the organic carbon was removed, which is a 5 fold increase compared to the ACF. The use of the HPC-loaded cathode in the EF system significantly strengthened the yield of hydrogen peroxide and effectively degraded organic pollutants with a lower energy consumption.

Degradation of sulfamethoxazole in aqueous solution by dielectric barrier discharge plasma combined with Bi2WO6 -rMoS2 nanocomposite: Mechanism and degradation pathway

The feasibility of pollutant removal in aqueous solution by dielectric barrier discharge plasma in combination with Bi2WO6-rMoS2 composite photocatalyst was investigated by choosing sulfamethoxazole (SMZ) as the model pollutant. In this study, Bi2WO6-rMoS2 catalysts were synthesized by a modified hydrothermal method and characterized by TEM, XRD, XPS. The results showed that the Bi2WO6 was well loaded on the surface of MoS2. The influences of the main operating parameters including discharge voltage, initial concentration, initial pH, mass ratios and dosages of Bi2WO6-rMoS2 on the removal efficiency of SMZ were studied. The results revealed that the initial concentration of 20 mg L−1 SMZ solution (100 mL) could be degraded by 97.6% with the addition of 0.08 g L−1 Bi2WO6-rMoS2 (1 wt%) at 9 kV after 21 min, compared with 72.5% by single dielectric barrier discharge plasma. Even after four cycling runs, Bi2WO6-rMoS2 (1 wt%) still remained high removal efficiency of SMZ. Moreover, the yields of hydrogen peroxide (H2O2) and Ozone (O3) in plasma discharge process were also investigated, and the results exhibited that adding Bi2WO6-rMoS2 could notably influence the amount of O3 and H2O2. Finally, ten intermediates of SMZ degradation were identified, and the proposed SMZ degradation pathways were deduced based on the detected intermediates.

Peroxide Yield of the (001) La0.6Sr0.4MnO3 Surface as a Bifunctional Electrocatalyst for the Oxygen Reduction Reaction and Oxygen Evolution Reaction in Alkaline Media

AbstractActive and stable bifunctional electrocatalysts are required for large‐scale deployment of rechargeable metal‐air and metal‐O2 batteries. This is hindered by the large overpotentials of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline media, where peroxide is an undesired side product. We study the suitability of epitaxial (001)‐oriented La0.6Sr0.4MnO3 perovskite surfaces as a bifunctional catalyst using a rotating‐ring disk electrode (RRDE) assembly and focus particularly on the selectivity of the ORR. The peroxide yield is above 50 % during ORR‐only investigations in the scan range of 0.69 to 0.99 V vs. RHE where the CV traces are reproducible. In contrast, the peroxide yield is drastically reduced during OER‐ORR cycling where a peroxide yield below 10 % is reached during the ORR in the scan range of 0.74 V to 1.74 V vs. RHE. Our study highlights the importance of the electrode history and thus clearly demonstrates that separate studies of the OER and ORR are insufficient to optimize bifunctional electrocatalysts.

B, N Co-Doped Three-Dimensional Carbon Aerogels with Excellent Electrochemical Performance for the Oxygen Reduction Reaction.

Herein, an ordinary and mass-production approach is reported to synthesize boron (B) and nitrogen (N) co-doped three-dimensional (3D) carbon aerogels (CA) by using glucose and borax as the raw materials by a simple hydrothermal method and then carbonization in NH3 atmosphere. The porous material (BN-CA-900) possesses a large specific surface area (1032 m2 g-1 ) and high contents of doped pyridinic N and graphitic N. The onset potential (0.91 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.77 V vs. RHE), and current density (5.70 mA cm-2 at 0.2 V vs. RHE) of BN-CA-900 for ORR are similar to those of commercial Pt/C, indicating that BN-CA-900 has a comparable catalytic activity with Pt/C in alkaline media. The number of electron transfer is 3.86-3.99 and the yield of hydrogen peroxide is less than 6.8 %. BN-CA-900 also presents decent catalytic performance in acidic medium. Moreover, the stability and methanol tolerance of BN-CA-900 are superior to commercial Pt/C in both alkaline and acidic media. The prepared BN-CA-900 is a promising candidate that may be applied in other areas, such as the adsorption of pollution, porous conductive electrodes, and lithium-ion batteries.

Harnessing inherently hierarchical microstructures of plant biomass to construct three-dimensional nanoporous nitrogen-doped carbons as efficient and durable oxygen reduction electrocatalysts.

Exploiting the natural structures of plants to prepare high-performance carbon-based electrocatalysts is highly desirable. Herein, the inherently hierarchical microstructures of Euphorbia tirucalli (E. tirucalli) are employed to construct three-dimensional nanoporous nitrogen-doped carbons that act as efficient and durable electrocatalysts towards the oxygen reduction reaction (ORR). During the preparation process, agar is used in order to reduce the dissipation of nitrogen and to protect the fine structures of E. tirucalli. The as-prepared ORR catalyst, with a high density of pyridinic and graphitic nitrogens, presents a high catalytic activity (onset potential of 0.97 V vs. RHE, half-wave potential of 0.82 V vs. RHE, limiting current density of 5.64 mA cm−2 and Tafel slope of 59 mV dec−1), four-electron pathway, low peroxide yield, long-term stability (current retention of 95.3% after 50 000 s) and strong methanol tolerance in 0.1 M KOH, all superior to the benchmark 20% Pt/C commercial catalyst. This work demonstrates an effective method for the utilization of inherently hierarchical microstructures of plant biomass to make efficient and durable carbon-based metal-free ORR electrocatalysts.

Minimizing the Abnormal High-Potential Discharge Process Related to Redox Mediators in Lithium-Oxygen Batteries.

Nonaqueous lithium-oxygen batteries can achieve a reduced charge potential when an available redox mediator is introduced. However, there are accompanying problems, such as the shuttle effect and the abnormal high-potential discharge process (>2.96 V) after the first cycle. The shuttle effect can be addressed by developing a blocking separator or resistant solid electrolyte interphase on the anode. No attention has been paid to the abnormal discharge process. Here, we unravel the underlying mechanism causing the undesired abnormal phenomenon. Our results show that the slow reaction rate between the discharged lithium peroxide and redox mediator and the low yield of lithium peroxide should take primary responsibility for the abnormal discharge issue. The sluggish reaction kinetics results from the formed byproducts covering lithium peroxide. We propose developing redox mediator-containing hydrate-melt lithium-oxygen batteries. The lithium hydroperoxide intermediator shows high reaction activity with the redox mediator and improves battery charge ability, thus solving the abnormal discharge problem. This work sheds light on the further design of lithium-oxygen batteries using a redox mediator.

The synthesis of phenanthroline and bipyridine based ligand for the preparation of Fe-Nx/C type electrocatalyst for oxygen reduction

In this study, we synthesized a nitrogen rich compound (FPPHA) as the precursor of oxygen reduction reaction (ORR) catalysts, which was prepared based on 1,10-phenanthroline-5-amine and 2,2’-bipyridyl-5,5’-dialdehyde. The FPPHA-Fe complex was formed and be loaded on the carbon powder to form the FPPHA-Fe/C composite catalyst. The pyrolysis of the FPPHA-Fe/C composite was conducted at different temperatures, including 700 °C, 800 °C, and 900 °C, and the resultant pyrolyzed materials were designated to FPPHA-Fe/C-700, FPPHA-Fe/C-800, FPPHA-Fe/C-900, respectively. The physical characteristics of the catalysts were examined by powder X-ray diffraction (PXRD), Brunauer–Emmett–Teller analysis, X-ray photoelectron spectrometer (XPS) and scanning electron microscopy (SEM) etc. The ORR performance of the composite catalysts were evaluated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and rotating ring disk electrodes (RRDE) in an alkaline solution. The results suggested that the pyrolysis process has a positive effect on the ORR activity of the catalysts, and among the catalysts the Fe-FPPHA/C-800 had the most preferable performance, which reduces oxygen through a predominantly four electron pathway with an average electron transfer number of 3.86 and an average hydrogen peroxide yield of 6.7%.

Enhancing the yield of hydrogen peroxide and phenol degradation via a synergistic effect of photoelectrocatalysis using a g-C3N4/ACF electrode

In this work, a new activated carbon fiber (ACF) cathode modified with graphitic carbon nitride (g-C3N4) was developed, which enables the substantially improved production of H2O2 (up to 32.8 mg L−1) with relatively low energy consumption (10.9 kWh kg−1) compared to generation without g-C3N4 (4.09 mg L−1). The cathode was analyzed and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction, and it was proved that the synthesized g-C3N4 is a thin layer sheet with a large number of carbon particles and low defect porosity. The cathode manufacturing parameters were optimized, and the influences of H2O2 production including the cathode potential, pH value, aeration rate and performance stability were studied. These features improved the production of H2O2 by about more than 7 folds when optimized ratio of g-C3N4 was used, and the modified cathode kept stable performance of H2O2 generation in 5 cycles. Further discussed by linear sweep voltammetry, rotating disk electrode and contact angle analysis, the existence of g-C3N4 were found to accelerate the electron transfer rate, is advantageous to the surface of the oxygen reaction, but will not change the two electronic number of oxygen reduction reaction activities, and this leads to enhanced performance of hydrogen peroxide production and the possible mechanism was suggested. Finally, the cathode improve by g-C3N4 proved the degradation effect of phenol by photoelectric-Fenton process. Phenol was degraded completely, and 93.8% of the organic carbon was removed, which is more than 1.5 and 5 times the amount achieved using electro-Fenton and photo-Fenton degradation only. In the degradation process of phenol, electrocatalysis and photocatalysis, they were optimized to produce substantial synergistic effect, proving the great potential practical application of organic wastewater treatment.

Effect of the Irradiation Conditions on the Yield of Hydrogen Peroxide in Frozen Aqueous Solutions of Adenine Derivatives

Comparative results are presented from detecting hydrogen peroxide (H2O2) in aqueous solutions of adenine derivatives irradiated at 77 K in the near-UV range of wavelengths (λ = 260–400 and 290–460 nm). It is shown that the efficiency of H2O2 formation, estimated from the ratio of [H2O2] to the integral intensity of EPR signals observed in the irradiated samples, grew in the latter case. Based on the literature data, this increase is assumed to be due to specific features of the photoexcitation of aggregates of adenine derivatives that form in frozen aqueous solutions.

Recent Advances in the Direct Synthesis of Hydrogen Peroxide Using Chemical Catalysis—A Review

Hydrogen peroxide is an important chemical of increasing demand in today’s world. Currently, the anthraquinone autoxidation process dominates the industrial production of hydrogen peroxide. Herein, hydrogen and oxygen are reacted indirectly in the presence of quinones to yield hydrogen peroxide. Owing to the complexity and multi-step nature of the process, it is advantageous to replace the process with an easier and straightforward one. The direct synthesis of hydrogen peroxide from its constituent reagents is an effective and clean route to achieve this goal. Factors such as water formation due to thermodynamics, explosion risk, and the stability of the hydrogen peroxide produced hinder the applicability of this process at an industrial level. Currently, the catalysis for the direct synthesis reaction is palladium based and the research into finding an effective and active catalyst has been ongoing for more than a century now. Palladium in its pure form, or alloyed with certain metals, are some of the new generation of catalysts that are extensively researched. Additionally, to prevent the decomposition of hydrogen peroxide to water, the process is stabilized by adding certain promoters such as mineral acids and halides. A major part of today’s research in this field focusses on the reactor and the mode of operation required for synthesizing hydrogen peroxide. The emergence of microreactor technology has helped in setting up this synthesis in a continuous mode, which could possibly replace the anthraquinone process in the near future. This review will focus on the recent findings of the scientific community in terms of reaction engineering, catalyst and reactor design in the direct synthesis of hydrogen peroxide.

Optimized Process Conditions for Hydrogen Peroxide Generating Gas Diffusion Electrodes

In addition to the technical design of hydrogen peroxide-forming gas diffusion electrodes (GDE), the process conditions significantly determine the hydrogen peroxide yield. High yields are crucial for water purification, but also for decentralized and demand-oriented production of hydrogen peroxide solutions through renewable electricity at best. A technical-relevant scale of laboratory electrolysis with 100 square centimeters active area was used to evaluate the influence of process parameters such as temperature, current density, oxygen volume flow rate and difference pressure with respect to the H2O2-yield in alkaline media. At optimized operating conditions, a current efficiency above 90% is already possible with carbon GDEs. Especially lower electrolyte temperatures contribute to higher yields, which is beneficial for a technical process as wastewater very often has low temperature.

Morphology controlled synthesis of SmMn2O5 nanocrystals via a surfactant-free route for Zn-air batteries

Developing earth abundant and highly active electrocatalysts to overcome the sluggish oxygen reduction kinetics is one of the key toward the practical applications of air batteries with economic efficiency and high energy density. Herein, a shape-controlled synthesis of mullite SmMn2O5 is achieved through a surfactant-free one-step hydrothermal method. SmMn2O5 nanoparticles (SmMn2O5-NPs) and nanorods (SmMn2O5-NRs) are successfully synthesized and in half-cell tests, SmMn2O5-NRs perform enhanced oxygen reduction activity relative to SmMn2O5-NPs in terms of a more positive half-wave potential and reduced peroxide yield. Importantly, rechargeable zinc-air batteries constructed with SmMn2O5-NRs exhibit not only higher peak power density (217 mW cm−2) over commercial Pt/C catalyst (190 mW cm−2) but also excellent cycling stability during long-term charging-discharging test over 170 h. The facile synthesis of SmMn2O5-NRs together with the remarkable electrocatalytic performance endows mullite SmMn2O5 with great promise in replacing the precious metal as future catalysts for air batteries.