Trifunctional Electrocatalysts Research Articles

Interfacial electronic engineering of Ru/FeRu nanoparticles as efficient trifunctional electrocatalyst for overall water splitting and Zn-air battery

Rational design of multi-functional electrocatalyst for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is critical to energy conversion and storage technologies such as water splitting and metal-air batteries. However, explorations of specific interface structures for catalysts are still limited and challenging. Herein, a novel core–shell architecture comprising of Ru and FeRu hybrid enwrapped with a carbon shell anchored on nitrogen-doped carbon substrate (Ru-FeRu@C/NC) was constructed. Specifically, the interfacial electronic interaction between Ru and FeRu regulate the electron configuration and broaden the electron transfer pathway to boost its electrocatalytic performance. Particularly, Ru-FeRu@C/NC required ultralow overpotentials of 23 and 345 mV to drive a current density of 10 mA cm−2 for HER and OER, respectively, and a positive half-wave potential of 0.90 V versus reversible hydrogen electrode (RHE) for ORR. Furthermore, an electrocatalytic water splitting cell powered by a Zn–air battery was successfully fabricated using Ru-FeRu@C/NC as the “one-in-all” electrocatalyst. The present work paves the way for design and construction of efficient multifunctional electrocatalyst in energy conversion and storage.

Exploiting the Multifunctionality of M2+/Imidazole-Etidronates for Proton Conductivity (Zn2+) and Electrocatalysis (Co2+, Ni2+) toward the HER, OER, and ORR.

This work deals with the synthesis and characterization of one-dimensional (1D) imidazole-containing etidronates, [M2(ETID)(Im)3]·nH2O (M = Co2+ and Ni2+; n = 0, 1, 3) and [Zn2(ETID)2(H2O)2](Im)2, as well as the corresponding Co2+/Ni2+ solid solutions, to evaluate their properties as multipurpose materials for energy conversion processes. Depending on the water content, metal ions in the isostructural Co2+ and Ni2+ derivatives are octahedrally coordinated (n = 3) or consist of octahedral together with dimeric trigonal bipyramidal (n = 1) or square pyramidal (n = 0) environments. The imidazole molecule acts as a ligand (Co2+, Ni2+ derivatives) or charge-compensating protonated species (Zn2+ derivative). For the latter, the proton conductivity is determined to be ∼6 × 10–4 S·cm–1 at 80 °C and 95% relative humidity (RH). By pyrolyzing in 5%H2–Ar at 700–850 °C, core–shell electrocatalysts consisting of Co2+-, Ni2+-phosphides or Co2+/Ni2+-phosphide solid solution particles embedded in a N-doped carbon graphitic matrix are obtained, which exhibit improved catalytic performances compared to the non-N-doped carbon materials. Co2+ phosphides consist of CoP and Co2P in variable proportions according to the used precursor and pyrolytic conditions. However, the Ni2+ phosphide is composed of Ni2P exclusively at high temperatures. Exploration of the electrochemical activity of these metal phosphides toward the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) reveals that the anhydrous Co2(ETID)(Im)3 pyrolyzed at 800 °C (CoP/Co2P = 80/20 wt %) is the most active trifunctional electrocatalyst, with good integrated capabilities as an anode for overall water splitting (cell voltage of 1.61 V) and potential application in Zn–air batteries. This solid also displays a moderate activity for the HER with an overpotential of 156 mV and a Tafel slope of 79.7 mV·dec–1 in 0.5 M H2SO4. Ni2+- and Co2+/Ni2+-phosphide solid solutions show lower electrochemical performances, which are correlated with the formation of less active crystalline phases.

Interfacial coupling porous cobalt nitride nanosheets array with N-doped carbon as robust trifunctional electrocatalysts for water splitting and Zn-air battery

Compositional and structural engineering of high-performance catalysts is vital for electrochemical catalysis, but challenges remain in their facile synthesis and efficient controls. Herein, a novel vaporization-nitridation synthesis strategy with simple operation is developed to prepare hierarchically porous cobalt nitride hybrid nanosheets grown on Ni foam by coupling cobalt nitride with N-doped carbon (CoN@NC). Benefitting from the highly open 3D hierarchical porous architecture and strong coupling effect between CoN and NC, the obtained CoN@NC electrode possesses accelerated ion and electron transfer. Moreover, the transform from CoN to CoOOH during water oxidation is confirmed by in-situ Raman characterizations, which together with NC and CoN species afford multiple active sites. The optimized CoN@NC-300 exhibits remarkable trifunctional catalytic activity towards OER, HER and ORR. Consequently, a two-electrode electrolyzer based on CoN@NC-300 needs only a voltage of 1.53 V to achieve the current density of 10 mA cm−2. Moreover, the flexible Zn-air battery assembled with CoN@NC exhibits high performance and superior durability. This work offers a novel method for designing metal nitride hybrids as highly efficient multifunctional electrocatalysts towards electrocatalysis and energy storage.

Strategic design of cellulose nanofibers@zeolitic imidazolate frameworks derived mesoporous carbon-supported nanoscale CoFe2O4/CoFe hybrid composition as trifunctional electrocatalyst for Zn-air battery and self-powered overall water-splitting

A novel “Nucleation growth & Spatial isolation” strategy is reported to construct the high-efficient multifunctional electrocatalyst via pyrolysis of the cellulose nanofibers (CNFs) coating with Fe embedded bimetal-zeolitic imidazolate frameworks (ZIFs) of ZIF-67/ZIF-8. Taking advantages of strategically structural design effectively inhibits Fe/Co metal species migration and agglomeration during the pyrolysis process, deriving the nanoscale-dispersed CoFe 2 O 4 /CoFe active sites and abundant mesoporous structure which ensures more effective exposure in the optimized FeZn 4 Co@CNFs sample. With a half-wave potential E 1/2 of 0.84 V for oxygen reduction reaction (ORR), small overpotential 0.36 V and 0.20 V for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, FeZn 4 Co@CNFs presents the one of most Fe/Co-based trifunctional electrocatalysts reported to date, also is comparable to the benchmark Pt/C and RuO 2 catalysts. Furthermore, a rechargeable FeZn 4 Co@CNFs-based Zn-air battery endows a high power density of 107.6 mW cm −2 and an outstanding cycling stability. Remarkably, the overall water-splitting is successfully driven by FeZn 4 Co@CNFs-based Zn-air batteries for generating H 2 and O 2 bubbles. Our finding provides a new guidance to strategic design and develop nanoscale-dispersed active sites in non-noble metal trifunctional electrocatalysts. • A novel “Nucleation growth & Spatial isolation” strategy is developed. • The nanoscale-dispersed CoFe 2 O 4 /CoFe active sites are obtained. • FeZn 4 Co@CNFs exhibits the outstanding ORR, OER and HER activities. • The assembled rechargeable Zn-air battery provides a high power density. • The overall water-splitting is driven by FeZn 4 Co@CNFs based Zn-air batteries.

In situ simultaneously integrating Co-N-C sites and Co9S8 nanoparticles into N,S-doped porous carbon as trifunctional electrocatalysts for Zn–air batteries driving water splitting

Developing cost-effective, but efficient and stable trifunctional catalysts synchronously for oxygen reduction (ORR), oxygen evolution (OER) and hydrogen evolution reaction (HER) under same electrolytes is essential for the real application of renewable energy systems. Herein, we report the synthesis of a cheap and high-efficiency electro-catalyst based on Co9S8 nanoparticles decorated with Co-N-C sites well anchored to metal-porous organic polymer (MPOP)-derived N, S-codoped carbon (Co-IM-POP-1000), which exhibits pronounced trifunctional electrocatalytic activity for ORR, OER and HER, simultaneously, in alkaline media. Consequently, breathing Zn–air batteries (ZABs) employing Co-IM-POP-1000 as the sole catalysts present prominent performance, i. e., the charge/discharge voltage, power and energy density, specific capacity, rate performance as well as the lifetime, outperforming that of Pt/C 20% + RuO2 counterparts, which could be regenerated and maintained at the same performance level for subsequent runs by simply replenishing the Zn anode and electrolyte. An alkaline water splitting system using the IM-POP-Co-1000 as catalyst for overall water splitting affords a cell voltage as low as 1.60 V at 10 mA cm−2. A self-driven water splitting system powered by the home-made ZABs is demonstrated using IM-POP-Co-1000 as the sole catalyst in 0.1 M KOH, giving a high H2 evolution rate of 0.244 mmol h−1. These novel metal-POPs provides an effective strategy to prepare high-performance POPs for special applications. Therefore, this study shows a promising approach for the utilization of low cost and massive producible POPs as precursor for the preparation of stable and efficient trifunctional electro-catalyst toward clear energy applications.

Heterointerface Engineering of Hierarchically Assembling Layered Double Hydroxides on Cobalt Selenide as Efficient Trifunctional Electrocatalysts for Water Splitting and Zinc-Air Battery.

Engineering of structure and composition is essential but still challenging for electrocatalytic activity modulation. Herein, hybrid nanostructured arrays (HNA) with branched and aligned structures constructed by cobalt selenide (CoSe2) nanotube arrays vertically oriented on carbon cloth with CoNi layered double hydroxide (CoSe2@CoNi LDH HNA) are synthesized by a hydrothermal‐selenization‐hybridization strategy. The branched and hollow structure, as well as the heterointerface between CoSe2 and CoNi LDH guarantee structural stability and sufficient exposure of the surface active sites. More importantly, the strong interaction at the interface can effectively modulate the electronic structure of hybrids through the charge transfer and then improves the reaction kinetics. The resulting branched CoSe2@CoNi LDH HNA as trifunctional catalyst exhibits enhanced electrocatalytic performance toward oxygen evolution/reduction and hydrogen evolution reaction. Consequently, the branched CoSe2@CoNi LDH HNA exhibits low overpotential of 1.58 V at 10 mA cm−2 for water splitting and superior cycling stability (70 h) for rechargeable flexible Zn‐air battery. Theoretical calculations reveal that the construction of heterostructure can effectively lower the reaction barrier as well as improve electrical conductivity, consequently favoring the enhanced electrochemical performance. This work concerning engineering heterostructure and topography‐performance relationship can provide new guidance for the development of multifunctional electrocatalysts.

Valence Engineering of Polyvalent Cobalt Encapsulated in a Carbon Nanofiber as an Efficient Trifunctional Electrocatalyst for the Zn-Air Battery and Overall Water Splitting.

The rapid development of electrochemical power systems has prompted high demand for nonprecious trifunctional electrocatalysts with superior performance, prolonged stability, and low cost for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Here, a valence engineering strategy is devised to construct a morphology with polyvalent cobalt encapsulated in nitrogen-doped carbon nanofibers (Co/N-CNFs). The diverse cobalt valence states of the Co/N-CNF catalysts contribute to their excellent catalytic effect and high durability in multiple electrochemical processes. The optimal Co/N-CNF catalyst fabricated exhibits a high half-wave potential of ORR (0.86 V) and low overpotentials of OER (380 mV) and HER (241 mV) at 10 mA cm-2. The Co/N-CNF-based Zn-air battery possesses a high charge-discharge efficiency as well as a good cycle stability (50 h at 10 mA cm-2 and 120 h at 20 mA cm-2), much superior to the Pt/C-based batteries. Furthermore, the Co/N-CNF catalyst could perform efficient overall water splitting.

Construction of three-dimensional cobalt sulfide/multi-heteroatom co-doped porous carbon as an efficient trifunctional electrocatalyst.

Exploring cost-effective non-precious metal electrocatalysts is vital for the large-scale application of clean energy conversion devices (i.e., fuel cells, metal-air batteries and water electrolysers). Herein, we present the construction of a three-dimensional cobalt sulfide/multi-heteroatom co-doped carbon composite as a trifunctional electrocatalyst for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) through one-step sulfidation of zeolitic-imidazolate frameworks (ZIFs) using sulfur powder as a sulfur source. By virtue of the distinct periodic metal-nitrogen coordination structure and the abundant micropores within the ZIF precursor, sub-10 nm Co9S8 nanoparticles (NPs) are homogenously anchored on a Co, S and N multi-heteroatom co-doped carbon framework with a large specific surface area that exposes sufficient reactive sites for these electrocatalytic reactions. The optimized Co9S8/CoNSC exhibits outstanding ORR, OER and HER performance, comparable or even superior to those of commercial Pt/C and RuO2. The small Co9S8 NPs and Co-Nx species embedded in the carbon matrix cooperatively catalyze the OER and ORR, while the HER catalysis is mainly contributed by Co9S8 NPs. Furthermore, the Co9S8/CoNSC shows outstanding anti-poisoning capability towards sulfur species during ORR catalysis with no obvious activity degradation observed in 0.1 M KOH containing 50 μM SO32- species, significantly outperforming commercial Pt/C. The assembled rechargeable Zn-air battery using the Co9S8/CoNSC as a cathode shows a high power density (150 mW cm-2) and the assembled water electrolyzer only requires 1.585 V at a current density of 10 mA cm-2 when using this material as an anode and a cathode. This work provides an effective strategy to design and synthesize efficient, durable and anti-poisoning cobalt chalcogenide-based trifunctional electrocatalysts for the large-scale application of clean energy conversion devices.

Recent advances in the metal-organic framework-based electrocatalysts for trifunctional electrocatalysis.

The sustainable energy technology is in great demand due to the depletion and the risks associated with the use of fossil fuels. Various energy technologies like regenerative fuel cells, zinc-air batteries, and overall water-splitting devices have a huge scope in the growth of green energy. The efficiency of these devices is reliant upon the multifunctional electrocatalysts, which include both bifunctional and trifunctional electrocatalysts. Among the different categories of the materials used for such multifunctional electrocatalysis, metal-organic-frameworks (MOFs) occupy a very consolidated place because of their high surface area, porosity, and many other unique physicochemical properties. However, the use of MOFs for the trifunctional electrocatalytic applications is in the budding phase and needs to be explored more. Further, most of these MOF-based trifunctional electrocatalysts are derived by pyrolyzing MOFs at high temperatures. Therefore, there is a need to develop more conductive MOFs which can be directly utilized for the trifunctional applications. In this frontier article, we present the latest reports on the MOF-based materials for trifunctional applications. The material design strategies of the MOF-based materials for trifunctional electrocatalysis have been discussed. The progressive improvements made with MOFs in electrocatalytic applications have been provided with emphasis on the structural, active site and compositional requirements. Finally, the challenges and viewpoints on the future development of the MOF-based materials for trifunctional electrocatalysis have been provided.

Three-dimensional nano-framework CoP/Co2P/Co3O4 heterojunction as a trifunctional electrocatalyst for metal–air battery and water splitting

Three-dimensional nano-framework CoP/Co2P/Co3O4 heterojunctions exhibit superior trifunctional electrocatalyst performances toward metal–air batteries and water splitting.

Facile synthesis of Fe2P/Co embedded trifunctional electrocatalyst for high-performance anion exchange membrane fuel cells, rechargeable Zn–air batteries, and overall water splitting

A trifunctional electrocatalyst was synthesized via a facile one-pot pyrolysis process. The synergistic effect of Fe2P and Co nanoparticles significantly enhances the electrocatalytic performances of fuel cells, Zn–air batteries and overall water splitting.

Dimethylimidazole and dicyandiamide assisted synthesized rich-defect and highly dispersed CuCo-Nx anchored hollow graphite carbon nanocages as efficient trifunctional electrocatalyst in the same electrolyte

This paper introduces a facile method to disperse rich-defect CuCo-N x active sites onto hollow graphite carbon nanocages, through one-pool dicyandiamide-assisted pyrolysis of porous CuCo-PBA-2MI precursor. The as-prepared CuCo-N x @N-CCs composites exhibit favorable electrocatalytic activity and robust durability for oxygen reversible catalysis (ORR/OER) and hydrogen evolution reaction (HER) in the same low concentration alkaline electrolyte (0.1 M KOH), including E ORR, 1/2 = 0.80 V, E OER, 10 = 1.58 V and E HER, 10 = −0.319 V. The nanocomposites show the superior electrocatalytic practical application in Zn-air batteries self-driven overall water splitting. Insights into the experimental analyses reveal that during the pyrolysis process, CuCo-PBA-2MI precursor captures volatile CN x active species from dicyandiamide, eventually forming high dispersed CuCo-N x active sites with unique N-doped porous hollow carbon scaffolds structure. Such hollow nanocage structures can effectively protect the active site from agglomeration and uneven distribution. It also prevents nanomaterials corrosion from alkaline electrolyte in the electrocatalytic reaction process. We believe that this strategy will offer useful guidelines to researchers who are interested in developing advanced and performance-oriented multifunctional electrocatalysts for clean energy devices. • Dimethylimidazole promoted the generation of hollow nanocage. • Dimethylimidazole acts as both a competitive ligand and a carbon/nitrogen source. • The dimethylimidazole and dicyandiamide make CuCo-N x active sites uniformly dispersed. • Unique hollow nanocage structure can prevent agglomerate and shedding of active sites. • CuCo-N x @N-CCs has excellent trifunctional electrocatalytic properties in same electrolyte.

Popcorn-like Co3O4 nanoparticles confined in a three-dimensional hierarchical N-doped carbon nanotube network as a highly-efficient trifunctional electrocatalyst for zinc–air batteries and water splitting devices

A novel unique 3D hierarchical structural electrocatalyst is synthesized, where popcorn-like Co3O4 nanoparticles coated with N-doped amorphous carbon anchor onto the tips of N-doped carbon nanotubes (NCNTs), and the NCNTs grow on carbon nanofiber.

Vacancies and interfaces engineering of core–shell heterostuctured NiCoP/NiO as trifunctional electrocatalysts for overall water splitting and zinc-air batteries

The electronic structures and properties of electrocatalysts, which depend on the physicochemical structure and metallic element components, could significantly affect their electrocatalytic performance and their future applications in Zn-air battery (ZAB) and overall water splitting (OWS). Here, by combining vacancies and heterogeneous interfacial engineering, three-dimensional (3D) core–shell NiCoP/NiO heterostructures with dominated oxygen vacancies have been controllably in-situ grown on carbon cloth for using as highly efficient electrocatalysts toward hydrogen and oxygen electrochemical reactions. Theoretical calculation and electrochemical results manifest that the hybridization of NiCoP core with NiO shell produces a strong synergistic electronic coupling effect. The oxygen vacancy can enable the emergence of new electronic states within the band gap, crossing the Fermi levels of the two spin components and optimizing the local electronic structure. Besides, the hierarchical core–shell NiCoP/NiO nanoarrays also endow the catalysts with multiple exposed active sites, faster mass transfer behavior, optimized electronic strutures and improved electrochemical performance during ZAB and OWS applications.

Carbon-based iron-cobalt phosphate FeCoP/C as an effective ORR/OER/HER trifunctional electrocatalyst

Efficient catalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are of paramount importance for electrochemical energy applications. Herein, a high-efficient carbon-based trifunctional electrocatalyst FeCoP/C is synthesized through a simple one-step supramolecular-assisted method, in which a supramolecular gel structure is formed by phosphoric acid and melamine to allow the efficient and homogeneous incorporation of highly active species. Experimentally, the as-obtained catalysts exhibit practical trifunctional activities in the ORR, OER, and HER. In alkaline electrolytes, requiring overpotentials of 95 and 282 mV to deliver a current density of 10 mA cm−2 for HER and OER, respectively, and presents the significantly increased alkalic ORR activity, with the half-wave potential of 0.849 V. Furthermore, the FeCoP/C also showed good integrated capabilities for Zn-air batteries. This supramolecular-assisted strategy could bring new inspiration to boost the electrocatalytic performance of transition metal-based electrocatalysts for energy conversion applications.

Supramolecular Modulation of Molecular Conformation of Metal Porphyrins toward Remarkably Enhanced Multipurpose Electrocatalysis and Ultrahigh‐Performance Zinc–Air Batteries (Adv. Energy Mater. 46/2021)

Zn–Air Batteries In article number 2102062, Yuxi Xu and co-workers report a supramolecular assembly strategy to induce molecular flattening of metal porphyrin molecules, which allows the metal porphyrin to act as a tri-functional electrocatalyst for the first time and achieve the best Zn–air battery based on molecular catalysts. This work demonstrates the concept of modulating molecular conformation for enhancing the intrinsic activity of molecular catalysts.

Double shelled hollow CoS2@MoS2@NiS2 polyhedron as advanced trifunctional electrocatalyst for zinc-air battery and self-powered overall water splitting

Electrocatalysts play important role in various energy conversion and storage devices. The catalytic performance of electrocatalysts can be enhanced through the increasement of intrinsic catalytic activity by optimizing electronic structure and the improvement of exposed active sites by designing proper nanostructures. In this work, CoS2@MoS2@NiS2 nano polyhedron with double-shelled structure was prepared using metal organic framework as a precursor. Due to the rational integration of multifunctional active center, the strong electronic interaction of the various component, the high electrochemical surface area and shortened mass transport induced by the special structure, CoS2@MoS2@NiS2 exhibits high catalytic activity for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Specifically, low overpotentials of 156 and 200 mV was achieved to deliver a current density of 10 mA cm−2 for HER and OER, and a high half-wave potential of 0.80 V was observed for ORR. More importantly, the Zn-air battery assembled by CoS2@MoS2@NiS2 exhibits a high-power density of 80.28 mW cm−2 and could effectively drive overall water splitting. This work provides a new platform for designing multifunctional catalysts with high activity for energy conversion and storage.

RuCoOx Nanofoam as a High-Performance Trifunctional Electrocatalyst for Rechargeable Zinc-Air Batteries and Water Splitting.

Designing high-performance trifunctional electrocatalysts for ORR/OER/HER with outstanding activity and stability for each reaction is quite significant yet challenging for renewable energy technologies. Herein, a highly efficient and durable trifunctional electrocatalyst RuCoOx is prepared by a unique one-pot glucose-blowing approach. Remarkably, RuCoOx catalyst exhibits a small potential difference (ΔE) of 0.65 V and low HER overpotential of 37 mV (10 mA cm-2), as well as a negligible decay of overpotential after 200 000/10 000/10 000 CV cycles for ORR/OER/HER, all of which show overwhelming superiorities among the advanced trifunctional electrocatalysts. When used in liquid rechargeable Zn-air batteries and water splitting electrolyzer, RuCoOx exhibits high efficiency and outstanding durability even at quite large current density. Such excellent performance can be attributed to the rational combination of targeted ORR/OER/HER active sites into one electrocatalyst based on the double-phase coupling strategy, which induces sufficient electronic structure modulation and synergistic effect for enhanced trifunctional properties.

Strong coordination ability of sulfur with cobalt for facilitating scale-up synthesis of Co9S8 encapsulated S, N co-doped carbon as a trifunctional electrocatalyst for oxygen reduction reaction, oxygen and hydrogen evolution reaction

High activity trifunctional non-noble electrocatalysts, targeting oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER), are rationally designed by integrating the merits of both Co9S8 nanoparticles and carbons nanosheets. Herein, Co9S8 loaded with S, N co-doped carbon core–shell catalyst (Co9S8@SNC) was reasonably designed and synthesized by using the strong coordination effect between Co2+ and CS at the molecular level. The significant synergistic effect between the S, N co-doped carbon shell and Co9S8 core endows the catalyst with excellent catalytic performance for ORR, HER, and OER reactions. The carbon shell enhances the conductivity of the hybrid material, while the Co9S8 core provides the main catalytic active sites. More specifically, the half-wave potential for ORR is 0.846 mV, and the overpotential at 10 mA cm−2 for OER and HER are 320 mV and 170 mV, respectively. To test its practical application, zinc-air battery assembled by Co9S8@SNC shows a high power density of 239 mW cm−2, excellent rechargeability, and long cyclic stability. This work provides a promising and extensible method to in-situ synthesize core–shell metal sulfides loaded S, N co-doped carbon composites, which can be a promising candidate for electrocatalytic material in energy storage and conversion devices.

Accelerating Triple Transport in Zinc-Air Batteries and Water Electrolysis by Spatially Confining Co Nanoparticles in Breathable Honeycomb-Like Macroporous N-Doped Carbon.

Rational engineering electrode structure to achieve an efficient triple-phase contact line is vital for applications such as in zinc-air batteries and water electrolysis. Herein, a facile "MOF-in situ-leachingandconfined-growth-MOF" strategy is developed to construct a breathable trifunctional electrocatalyst based on N-doped graphitic carbon with Co nanoparticles spatially confined in an inherited honeycomb-like macroporous structure (denoted as Co@HMNC). The unique orderly arranged macroporous channels and the "ships in a bottle" confinement effect jointly expedite the triple transport, endowing the catalysts with fast reaction kinetics. As a result, the obtained Co@HMNC catalyst presents superb trifunctional performance with a positive half-wave potential (E1/2 ) of 0.90 V for oxygen reduction reaction (ORR), and low overpotentials of 318 and 51 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at 10 mA cm-2 , respectively. The Co@HMNC-based liquid Zn-air battery reaches a large specific capacity of 859 mA h gZn -1 , a high-power density of 198 mW cm-2 , and long-term stability for 375 h, suggesting its promise for actual applications.