Catalysts For Rechargeable Zinc-air Batteries Research Articles

Metal–organic framework–derived trimetallic particles encapsulated by ultrathin nitrogen-doped carbon nanosheets on a network of nitrogen-doped carbon nanotubes as bifunctional catalysts for rechargeable zinc–air batteries

Economical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalysts with high activity aimed at replacing precious metal catalysts for rechargeable zinc-air batteries (ZABs) must be developed. In this study, a multiple hierarchical-structural material is developed using a facile dielectric barrier discharge (DBD) plasma surface treatment, solvothermal reaction, and high-temperature carbonization strategy. This strategy allows for the construction of nanosheets using nitrogen-doped carbon (NC) material-encapsulated ternary CoNiFe alloy nanoparticles (NPs) on a network of NC nanotubes (NCNTs), denoted as CoNiFe–NC@p–NCNTs. Precisely, the presence of abundant CoNiFe alloy NPs and the formation of M–N–C active sites created by transition metals (cobalt, nickel, and iron) coupled with NC can provide superior OER/ORR bifunctional properties. Moreover, the prepared NC layers with a multilevel pore structure contribute to a larger specific surface area, exposing numerous active sites and enhancing the uniformity of electron and mass movement. The CoNiFe0.08–NC@p–NCNTs show remarkable dual functionality for electrochemical oxygen reactions (ORR half-wave potential of 0.811 V, limiting current density of 5.73 mA cm−2 measured with a rotating disk electrode at a rotation speed of 1600 rpm, and OER overpotential of 351 mV at 10 mA cm−2), which demonstrates similar ORR performance to 20 wt% Pt/C and better OER performance than the commercial RuO2. A liquid ZAB prepared using the proposed material has excellent bifunctionality with an open-circuit voltage of 1.450 V and long-term cycling stability of 230 h@10 mA cm−2.

CoTe2/NiTe2 heterojunction embedded in N-doped hollow carbon nanoboxes as high-efficient ORR/OER catalyst for rechargeable zinc-air battery

Interface engineering has been recognized as one of the most promising strategies for tuning the catalytic properties of catalysts. However, building well-defined nanointerfaces for efficient oxygen reduction/evolution reactions (ORR/OER) remains a challenge. Herein, a hollow heterostructure composed of highly-dispersed CoTe2 inside the mesoporous walls of nitrogen-doped carbon nanoboxes and uniformly-dispersed NiTe2 outside the mesoporous walls (H-CoTe2/NiTe2@NCBs) is designed via a ZIF67-involved etching-anchoring-tellurization strategy. Promising half-wave potential of 0.86 V and overpotential of 320 mV at 10 mA cm−2 are obtained by H-CoTe2/NiTe2@NCBs. The excellent ORR/OER activity of H-CoTe2/NiTe2@NCBs is ascribed to the synergistic coupling based on nanointerfaces between CoTe2 and NiTe2. Density functional theory calculations confirm that the nanointerface-based electronic coupling between CoTe2 and NiTe2 facilitates the charge transfer between two components and generates abundant catalytically active sites at the heterointerface, thereby significantly promoting the ORR/OER activities. This work provides the design principles for transitional bimetallic tellurides as bifunctional electrocatalysts.

Renewable lignin-derived heteroatom-doped porous carbon nanosheets as an efficient oxygen reduction catalyst for rechargeable zinc-air batteries

Lignin upgrading to various functional products is promising to realize high-value utilization of low-cost and renewable biomass waste, but is still in its infancy. Herein, using industry waste lignosulfonate as the biomass-based carbon source and urea as the dopant, we constructed a heteroatom-doped porous carbon nanosheet structure by a simple NaCl template-assisted pyrolytic strategy. Through the synergistic effect of the NaCl template and urea, the optimized lignin-derived porous carbon catalyst with high content of active nitrogen species and large specific surface area can be obtained. As a result, the fabricated catalysts exhibited excellent electrocatalytic oxygen reduction activity, as well as good methanol tolerance and stability, comparable to that of commercial Pt/C. Moreover, rechargeable Zn-air batteries assembled with this electrocatalyst have a peak power density of up to 150 mW cm-2 and prominent long-term cycling stability. This study offers an inexpensive and efficient way for the massive production of highly active metal-free catalysts from the plentiful, inexpensive and environmentally friendly lignin, offering a good direction for biomass waste recycling and utilization.

NiFe layered double hydroxide (LDH) anchored, Fe single atom and nanoparticle embedded on nitrogen-doped carbon-CNT (carbon nanotube) framework as a bifunctional catalyst for rechargeable zinc-air batteries

Zinc-air batteries (ZAB) have significant potential for practical energy storage, but their rechargeability has been limited by the lack of a suitable bifunctional catalyst. Here, we developed NiFe LDH-A-Fe/NC-CNT, a remarkable bifunctional catalyst that is built on a hierarchically porous nitrogen-doped carbon and carbon nanotube (NC-CNT) framework enriched with iron single atoms and nanoparticles, with nickel‑iron layered double hydroxides (NiFe LDH) anchored onto it. The NiFe LDH-A-Fe/NC-CNT exhibited remarkable performance in the ORR, with Eonset of 0.94 V, a half-wave potential of 0.84 V, and a limited current of 6.89 mA cm−2. A remarkable Eonset of 1.47 V and a potential of 1.59 V at 10 mA cm−2 (Ej = 10) in the OER were also observed. Significantly, the difference in potential (ΔE) between the ORR and OER was only 0.74 V. The stability tests, tolerance assessments, and poisoning experiments consistently demonstrated the superior performance of this cutting-edge catalyst in comparison to the commercial Pt/C and RuO2. In ZAB tests, it achieves a discharge capacity of 818 mAhg−1 and an impressive power density of 293 mWcm−2, enduring nearly 1000 cycles (320h). Flexible ZABs with this catalyst maintain a 629 mAhg−1 capacity, a power density of 195 mWcm−2, and a lifespan of 95 h (280 cycles), outperforming benchmark catalysts. In conclusion, a remarkable bifunctional catalyst was synthesized, demonstrating its immense capacity for utilization in zinc-air batteries.

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.

Regulating the frontier orbital of iron phthalocyanine with nitrogen doped carbon nanosheets for improving oxygen reduction activity.

Iron phthalocyanine (FePc) has attracted widespread attention for its tunable electronic structure. However, the Fe-N sites suffer from undesirable oxygen reduction activity due to the symmetric geometries. A suitable substrate was thus needed to induce electron redistribution around Fe-N to improve the activity. Herein, ultrathin nitrogen-doped carbon nanosheets (N-CNSs) were prepared by a simple high temperature pyrolysis. Then iron phthalocyanine was loaded on the ultrathin nitrogen-doped carbon nanosheets (FePc@N-CNSs) by a low-cost and simple solution method. This composite catalyst shows an excellent ORR activity with a half potential of 0.88 V, an onset potential of 0.99 V and durability superior to commercial Pt/C. When used as an air cathode catalyst for rechargeable zinc-air batteries, FePc@N-CNS modified batteries outperform Pt/C + RuO2 modified batteries with higher power density and superior constant current charge-discharge cycling stability of 37 hours. The regulated electronic structure of FePc by the N-CNS substrate was revealed further by DFT calculations, which explained the enhanced adsorption of the active center to the intermediates and the increased ORR performance.

Bifunctional Single Atom Catalysts for Rechargeable Zinc-Air Batteries: From Dynamic Mechanism to Rational Design.

Ever-growing demands for rechargeable zinc-air batteries (ZABs) call for efficient bifunctional electrocatalysts. Among various electrocatalysts, single atom catalysts (SACs) have received increasing attention due to the merits of high atom utilization, structural tunability, and remarkable activity. Rational design of bifunctional SACs relies heavily on an in-depth understanding of reaction mechanisms, especially dynamic evolution under electrochemical conditions. This requires a systematic study in dynamic mechanisms to replace current trial and error modes. Herein, fundamental understanding of dynamic oxygen reduction reaction and oxygen evolution reaction mechanisms for SACs is first presented combining in situ and/or operando characterizations and theoretical calculations. By highlighting structure-performance relationships, rational regulation strategies are particularly proposed to facilitate the design of efficient bifunctional SACs. Furthermore, future perspectives and challenges are discussed. This review provides a thorough understanding of dynamic mechanisms and regulation strategies for bifunctional SACs, which are expected to pave the avenue for exploring optimum single atom bifunctional oxygen catalysts and effective ZABs.

FeNiCrCoMn High-Entropy Alloy Nanoparticles Loaded on Carbon Nanotubes as Bifunctional Oxygen Catalysts for Rechargeable Zinc-Air Batteries.

An efficient and stable bifunctional oxygen catalyst is necessary to complete the application of the rechargeable zinc-air battery. Herein, an economical and convenient process was adopted to successfully coat high-entropy alloy Fe12Ni23Cr10Co55-xMnx nanoparticles on carbon nanotubes (CNTs). In 0.1 M KOH solution, with a bifunctional oxygen overpotential (ΔE) of only 0.7 V, the catalyst Fe12Ni23Cr10Co30Mn25/CNT exhibits excellent bifunctional oxygen catalytic performance, exceeding most catalysts reported so far. In addition, the air electrode assembled with this catalyst exhibits high specific capacity (760 mA h g-1) and energy density (865.5 W h kg-1) in a liquid zinc-air battery, with a long-term cycle stability over 256 h. The density functional theory calculation points out that changing the atomic ratio of Co/Mn can change the adsorption energy of the oxygen intermediate (*OOH), which allows the ORR catalytic process to be accelerated in the alkaline environment, thereby increasing the ORR catalytic activity. This article has important implications for the progress of commercially available bifunctional oxygen catalysts and their applications in zinc-air batteries.

Hollow Raspberry-like CoSx/C Sub-Microspheres as a Highly Active Air Cathode Catalyst for Rechargeable Zinc-Air Batteries

Hollow Raspberry-like CoS_<i>x</i>/C Sub-Microspheres as a Highly Active Air Cathode Catalyst for Rechargeable Zinc-Air Batteries

Construction of Co/FeCo@Fe(Co)3O4 heterojunction rich in oxygen vacancies derived from metal–organic frameworks using O2 plasma as a high-performance bifunctional catalyst for rechargeable zinc-air batteries

Developing high-efficient, good-durability, and low-cost bifunctional non-precious metal catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is urgent and significant for promoting the practical rechargeable zinc-air batteries (RZABs). Herein, N-doped carbon coated Co/FeCo@Fe(Co)3O4 heterojunction rich in oxygen vacancies derived from metal–organic frameworks (MOFs) is successfully constructed by O2 plasma treatment. The phase transition of Co/FeCo to FeCo oxide (Fe3O4/Co3O4) mainly occurs on the surface of nanoparticles (NPs) during the O2 plasma treatment, which can form rich oxygen vacancies simultaneously. The fabricated catalyst P-Co3Fe1/NC-700-10 with optimal O2 plasma treatment time of 10 min can reduce the potential gap between the OER and ORR to 760 mV, which is much lower than commercial 20% Pt/C + RuO2 (910 mV). Density functional theory (DFT) calculation indicates that the synergistic coupling between Co/FeCo alloy NPs and FeCo oxide layer can promote the ORR/OER performance. Both liquid electrolyte RZAB and flexible all-solid-state RZAB using P-Co3Fe1/NC-700-10 as the air–cathode catalyst display high power density, specific capacity and excellent stability. This work provides an effective idea for the development of high performance bifunctional electrocatalyst and the application of RZABs.

Morphology Engineering toward High-Surface-Area Mno2 Bifunctional Catalysts for Rechargeable Zinc-Air Batteries

Morphology Engineering toward High-Surface-Area Mno2 Bifunctional Catalysts for Rechargeable Zinc-Air Batteries

Pomegranate-Like FeNC with Optimized FeN4 Configuration as Bi-Functional Catalysts for Rechargeable Zinc-Air Batteries.

Catalysts with FeNC moieties have demonstrated remarkable activity toward oxygen reduction reaction (ORR), but precise synthesis and configuration regulation of FeNC to achieve bi-functional catalytic sites for ORR and oxygen evolution reaction (OER) remain a great challenge. Herein, a pomegranate-like catalyst with optimized FeN4 configuration is designed. The unique framework affords a large surface area for sufficient active site exposure and abundant macroporous channels for mass transport. By twisting chemical bonds, the electronic structure of FeN4 is regulated, and the adsorption/desorption of oxygen species is facilitated. Compared to noble metal-based catalysts (Pt/C+IrO2 ), the optimized FeNC exhibits impressive onset potential (0.96V versus reversible hydrogen electrode), larger limiting current density (5.85mA cm-2 ), and better long-term life for ORR, as well as, lower OER overpotential. When integrated into Zn-air batteries, it demonstrates a respectable peak power density (71.6mW cm-2 ) and ideal cycling stability (30h), exceeding that of commercial Pt/C+IrO2 . The exploration offers a guideline for designing advanced bi-functional electrocatalysts.

Outstanding platinum group metal-free bifunctional catalysts for rechargeable zinc-air batteries

Developing highly active and durable catalysts for zinc-air batteries (ZAB) is critical for energy conversion and storage. Herein, we prepared Fe-N-C catalysts at a kilogram scale by the commercial VariPore™ method and the effect of synthesis conditions on the catalyst performance at ZAB air electrode was investigated. The results show the PA-450-HT exhibits excellent electrocatalytic activity toward oxygen reduction reaction (ORR) and it is the most suitable catalyst for primary ZAB with the galvanostatic polarization discharge peak power density of 149 mW cm−2, outperforming commercial Pt-Ru/C catalysts. Additionally, the NCB-600-HT catalyst displays the half-wave potential of 0.87 V vs. RHE for ORR and ∆E value of 0.81 V (indicating outstanding ORR and OER reversibility) and exhibits excellent charge-discharge cycling durability similar to NCB-550-LT around 160 h for the secondary ZAB. This work reports outstanding bifunctional Fe-N-C catalysts for rechargeable ZAB at mass production for the first time.

Fe-N4/Co-N4 active sites engineered porous carbon with encapsulated FeCo alloy as an efficient bifunctional catalyst for rechargeable zinc-air battery

Design and synthesis of earth-abundant elements-based electrocatalysts with sufficient activity and stability remain challenging for oxygen-involved electrochemical energy conversion and storage devices. In this work, catalyst with simultaneously engineered Fe-N4 and Co-N4 active sites and graphitic carbon multilayer-encapsulated FeCo alloy is developed by pyrolysis of metal salts doped G-g-C3N4. The obtained composite material exhibits promising catalytic activity and good stability for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte, as evidenced by the positive shift of half-wave potential by 44 mV compared to 20% Pt/C for ORR and the potential of 1.596 V at current density of 10 mAcm−2 for OER. In addition, the thus-assembled rechargeable zinc-air battery using the synthesized material as cathode delivers a maximum power density of 311.2 mWcm−2 with an open circuit potential of 1.51 V and a long-term cycling stability. DFT calculation results indicate that catalyst with composite active sites displays smaller energy barrier than that with single active site.

Ag Decorated Co3O4-Nitrogen Doped Porous Carbon as the Bifunctional Cathodic Catalysts for Rechargeable Zinc-Air Batteries

The use of transition metals as bifunctional catalysts for rechargeable zinc-air batteries has recently attracted much attention. Due to their multiple chemical valence states, the cobalt oxides are considered to be promising catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, bifunctional Ag-decorated Co3O4-nitrogen doped porous carbon composite (Co3O4-NC&amp;Ag) catalysts were synthesized by annealing ZIF-67 in N2 and O2, respectively, followed by Ag deposition using chemical bath deposition. Due to the decoration of Ag nanoparticles and high specific surface area (46.9 m2 g−1), the electrochemical activity of Co3O4 increased significantly. The optimized Co3O4-NC&amp;Ag catalysts possessed superior ORR performance with a half-wave potential of 0.84 V (vs. RHE) and OER activity with an overpotential of 349 mV at 10 mA cm−2. The open circuit voltage of the Co3O4-NC&amp;Ag-based zinc-air battery was 1.423 V. Meanwhile, the power density reached 198 mW cm−2 with a specific discharge capacity of 770 mAh g−1 at 10 mA cm−2, which was higher than that of Pt/C-based zinc-air battery (160 mW cm−2 and 705 mAh g−1). At a current density of 10 mA cm−2, the charge-discharge performance was stable for 120 h (360 cycles), exhibiting better long-term stability than the Pt/C&amp;RuO2 counterpart.

Nickel hydroxide anchored CNT-Co3O4-N-carbon bifunctional catalyst for rechargeable zinc-air batteries

BackgroundA rechargeable zinc-air battery (RZAB) is a hopeful alternative battery solution to meet the world's ever-increasing energy storage need. Developing a high-performance electrocatalyst is one of the most critical challenges that need to be addressed for the RZAB to fulfill that role. MethodsA Ni(OH)2-CNT-Co3O4/NC catalyst consisting of carbon nanotube (CNT), cobalt oxide, and nitrogen-doped functionalities embedded in a porous carbon framework with two-dimensional Ni(OH)2 nanosheets is reported. Significant findingsThe prepared catalytic material, Ni(OH)2-CNT-Co3O4/NC, showed a high limit current density of -6.409 mA cm−2 during the oxygen reduction reaction (ORR), surpassing that of the commercial Pt/C (-5.625 mA cm−2). The oxygen evolution reaction (OER) potential for this electrocatalyst also reached 1.653 V at a current density of 10 mA cm−2, which is close to that of the commercial RuO2 and thus showed excellent catalytic activity for the OER. As a bifunctional catalyst in the RZAB, the Ni(OH)2-CNT-Co3O4/NC electrocatalyst exhibited a high power density of 244.5 mW cm−2, and cycled 4500 times at a current density of 10 mA cm−2 while displaying good charge and discharge stability. Based upon these performances, we believe that the Ni(OH)2-CNT-Co3O4/NC catalyst can serve as an excellent bifunctional catalyst in the next-generation RZAB.

MOF-Derived Nanoporous Carbon As an Efficient Bifunctional Oxygen Electrocatalyst for Erzabs

Zinc-air batteries are cost-effective batteries that possess a high energy density (1086 Wh Kg-1), compared to other conventional battery systems. In order to improve the electrochemical performance of electrically rechargeable zinc-air batteries (ERZABs), an effective bifunctional oxygen electrocatalyst is required. Hence, the development of non-noble metal bifunctional catalysts for ORR and OER is of prime importance. The transition metal-based catalysts have increasing demand since they are promising alternatives, in terms of cost and durability, to noble metal catalysts. Metal-organic frameworks (MOF) based catalysts show high catalytic activity due to adjustable pore size, ultra-high surface area, and structural designability[1].Increasing porosity can augment the catalytic activity by increasing the surface area, thereby enhancing the ORR kinetics.In the present work, a CFZ-NPC (CoFeZn-MOF derived nanoporous carbon) was synthesized via hydrothermal method and investigated as a bifunctional catalyst for rechargeable zinc-air batteries[2]. The catalyst shows a high electrochemical activity towards oxygen reduction reaction with a half-wave potential of 830 mV vs. RHE and a comparable oxygen evolution activity (overpotential of 379 mV vs. RHE at 10 mA cm-2 ) with IrO2 (Over potential of 377 mV at 10 mA cm-2). The binder-free CFZ-NPC air electrode when applied into a Zinc-air battery system, delivers a low charge-discharge potential gap of 862 mV at 5 mA cm-2. Interestingly, the catalyst possesses an excellent electrochemical performance in the electrically rechargeable Zn-air battery over 1000 cycles at selected DOD for 157 h with a specific capacity of 890 mAh g(Zn) -1 without much efficiency drop.Financial support from Department of Science and Technology, Govt. of India under research grant number DST/TMD/MECSP/2K17/20 is gratefully acknowledged References; [1] Ren, Shuangshuang et al. 2020. “Bifunctional Electrocatalysts for Zn-Air Batteries: Recent Developments and Future Perspectives.” Journal of Materials Chemistry A 8(13): 6144–82.[2] Tang, Jing et al. 2016. “Bimetallic Metal-Organic Frameworks for Controlled Catalytic Graphitization of Nano porous Carbons.” Nature Publishing Group (April): 1-8.

MOF-derived nitrogen-doped carbon-based trimetallic bifunctional catalysts for rechargeable zinc-air batteries

Zinc-air battery (ZAB) is a promising new metal-air energy system, but the large overpotentials of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) around the air electrode lead to their poor energy efficiency. Herein, a novel bifunctional oxygen electrocatalyst is reported with the preparation of a zeolite imidazolate framework (ZIF-67) derived trimetallic composites decorated nitrogen-doped carbon, which consist of NiFe alloy and Co nanoparticles. The ZIF-derived porous N-doped carbon shell can speed up the mass transfer efficiency. Whereas the electronic effect between the formed NiFe alloy and Co nanoparticles, as well as the N-doped carbon framework can enrich the active centers and enhance the electrical conductivity. As a result, the NiFe-Co@NC-450 catalyst shows superior performance manifested as a small potential gap (ΔE = 0.857 V) between the overpotential at 10 mA cm−2 (E j=10) for OER (460 mV) and half-wave potential (E 1/2) for ORR (0.833 V). The liquid ZABs exhibit a high specific capacity reaching 798 mAh/gZn and a stable cycling performance at 10 mA cm−2 for more than 200 h. Meanwhile, the NiFe-Co@NC-450 based flexible ZABs also presents robust flexibility and stability. This study has certain implications for the development of economical, powerful and stable bifunctional catalysts for ZABs.

ZnS modified N, S dual-doped interconnected porous carbon derived from dye sludge waste as high-efficient ORR/OER catalyst for rechargeable zinc-air battery

Facile and rational design of high-efficient oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts is significant for rechargeable Zinc-air batteries. In this study, ZnS modified N, S dual-doped interconnected porous carbon (ZnS/NSC) derived from the dye sludge waste is successfully fabricated via a facile ZnCl2-assisted pyrolysis process. The effect of ZnCl2 and carbonization temperature on the microstructure and electrocatalytic performance is systematically investigated. By virtue of the synergistic effect between ZnS nanoparticles and N, S dual-doped porous carbon network, the obtained catalyst ZnS/NSC calcined at 1000 °C exhibits a decent bifunctional electrocatalytic performance with potential gap (ΔE=EOER,10-EORR,1/2) of 0.76 V comparable with commercial electrocatalysts (Pt/C and RuO2). In addition, a rechargeable zinc-air battery employed ZnS/NSC-1000 as the air cathode also displays the favorable electrochemical performance, in which the power density is 125 mW cm−2, the specific capacity is 763.27 mAh g−1 and the cycling stability at 10 mA cm−2 is more than 85 h, indicating a promising application prospect in rechargeable Zinc-air batteries.

Three-dimensionally ordered mesoporous trimetal sulfide as efficient electrocatalyst for rechargeable zinc-air batteries

Electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are indispensable in rechargeable zinc-air batteries. Herein, three-dimensional ordered macroporous N-doped trimetal sulfides (3DOM N-Co0.8Fe0.1Ni0.1Sx) bifunctional catalyst has been developed. The 3DOM porous structure provides rich channels for mass transportation and exposure of catalytic active sites. Together with the synergistic effect of trimetallic sulfide and N-doped carbon layer, this 3DOM catalyst exhibits excellent bifunctional catalytic activity, delivering an ORR half-wave potential of 0.80 V (vs RHE) and low OER overpotential of 370 mV at current density of 10 mA cm−2. The zinc-air battery with 3DOM N-Co0.8Fe0.1Ni0.1Sx achieves a stable cyclability with a lifetime of over 200 h at 10 mA cm−2. In-situ Raman analysis reveals that, during the OER process, surface reconstitution of the sulfide catalyst occurs, forming oxyhydroxides component. The latter is considered as the real OER catalytic phase. This study advances the design of efficient and durable nonprecious bifunctional catalysts for rechargeable zinc-air batteries.