Efficient Transport Pathways Research Articles

Cu3Se2 nanomeshes constructed by enoki-mushroom-like Cu3Se2 and their application to quantum dot-sensitized solar cells

Novel copper selenide (Cu3Se2) nanomeshes are synthesized on F-doped SnO2 (FTO) glass substrates via a facile single-step potentiodynamic electrodeposition method for efficient counter electrode (CE) in quantum dot-sensitized solar cells (QD-SSCs). The electrodeposited FTO/Cu3Se2 films consist of vertically standing Cu3Se2 nanomeshes, constructed by vertically and laterally grown enoki-mushroom-like Cu3Se2. The FTO/Cu3Se2 electrodes exhibit excellent electrocatalytic activity and good electrochemical stability for the S2−/Sn2− redox couple, even better than those of FTO/Cu2S and FTO/Pt. This is because the vertically standing Cu3Se2 nanomeshes provide not only high electrochemical active sites but also efficient charge transport pathways. Besides, high crystalline Cu3Se2 phase and widened pores between nanomeshes improve the electronic conduction and make ionic transport more efficient into and out of the film. As a result, the CdSe-based QD-SSC containing the optimized FTO/Cu3Se2 CE achieves a significantly increased power conversion efficiency of 5.5%, compared to those containing FTO/Cu2S and FTO/Pt CEs (4.52 and 2.62%, respectively).

One-dimensional mesoporous Co3O4 tubules for enhanced performance supercapacitor and enzymeless glucose sensing

One-dimensional hollow Co3O4 tubules have been synthesized by using a template method followed by a simple thermal annealing treatment. The obtained hollow Co3O4 nanomaterial displays one-dimensional architecture with a highly mesoporous nature and hollow interiors, leading to better electrolyte/electrode contact and more efficient transport pathways. Our experimental results demonstrate that the hollow Co3O4 nanostructures exhibit enhanced electrochemical performance for charge storage and enzymeless glucose sensing applications. Supercapacitor electrodes employing mesoporous hollow Co3O4 tubules exhibit specific capacitance of 326 F g−1 at a current density of 1 A g−1, a high capacity retention of 73.6% at 10 A g−1, and a long stable cycling performance of retaining ~ 91.6% after 5000 cycles. Compared with the bulk Co3O4, it also has good sensing ability for glucose with high sensitivity of 994.6 μA mM−1 cm−2 and 369.7 μA mM−1 cm−2 for the lower and higher concentration of glucose, fast response time of 5 s, detection limit as low as 0.84 μM, good selectivity, stability, and reproducibility. These results show that the hollow Co3O4 tubules is a versatile material for various applications.

Preciously Determining Energy Levels and Screening Extraction Medium to Design Highly Efficient Carriers Transport Pathways for Zn‐CuInS2 Quantum Dots Based H2 Generation Application

AbstractWith the creation of long‐lived defect states‐related donor‐acceptor pair (DAP) recombination pathway, the Zn doped CuInS2 quantum dots (CIZS QDs) sensitized TiO2 photoelectrode displayed a good photocurrent response ability with a density of 2.7 mA/cm2. Further introduction Au nanoparticles (NPs) between CIZS and TiO2, and the outermost layer CdS, the photocurrent of CdS‐CIZS−Au‐TiO2 reached 7.5 mA/cm2 with an increase of 75% and 175%, respectively. The enhancements both in photo‐conversion ability and photoelectrochemical hydrogen generation reactivity can be mainly attributed to the functions of Au NPs acting as electron traps to help separate the long‐lived carriers of CIZS QDs and subsequently improve interfacial charge transfer, as well as CdS's ability to enhance holes extraction.

One Dimensional Nanomaterials for Emerging Energy Storage

One-dimensional nanomaterials can offer large surface area, facile strain relaxation upon cycling and efficient electron transport pathway to achieve high electrochemical performance. Hence, nanowires have attracted increasing interest in energy related fields. We designed the single nanowire electrochemical device for in situ probing the direct relationship between electrical transport, structure, and electrochemical properties of the single nanowire electrode to understand intrinsic reason of capacity fading. The results show that during the electrochemical reaction, conductivity of the nanowire electrode decreased, which limits the cycle life of the devices. We have developed a facile and high-yield strategy for the oriented formation of CNTs from metal−organic frameworks (MOFs). The appropriate graphitic N doping and the confined metal nanoparticles in CNTs both increase the densities of states near the Fermi level and reduce the work function, hence efficiently enhancing its oxygen reduction activity. In addition, we demonstrated the critical role of structural H2O. The results suggest that the H2O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2O5 framework, effectively promoting its diffusion. We also identified the exciting electrochemical properties (including high electric conductivity, small volume change and self-preserving effect) and superior sodium storage performance of alkaline earth metal vanadates through preparing CaV4O9 nanowires. Furthermore, a novel assembled nanoarchitecture was also presented, which consists of V2O3 nanoparticles embedded in amorphous carbon nanotubes that are then coassembled within a reduced graphene oxide network. The naturally integrated advantages of each subunit exhibit highly stable and ultrafast sodium-ion storage. Our work presented here can inspire new thought in constructing novel one-dimensional structures and accelerate the development of energy storage applications.

High-performance supercapacitors based on reduced graphene oxide -wrapped carbon nanoflower with efficient transport pathway of electrons and electrolyte ions

Despite that a variety of carbon materials have been explored for electrochemical energy storage, rationally design the carbon structure for efficient electrons transfer and ions diffusion to further improve its performance is still a challenge. In this report, a novel three-dimension hybrid carbon material (NCNF/RGO) prepared from reduced graphene oxide (RGO) and N-doped carbon nanoflower (NCNF) consisting of carbon nanosheets has been fabricated by a hydrothermal treatment and freeze-drying method, and demonstrated as supercapacitor's electrode. Benefiting from such structure design with thin porous nanosheets, interworking mesoporous channel and RGO wrapping for efficient electrolyte ions diffusion and electrons transfer, the resulting hybrid electrode displays high specific capacitance of 344 F g−1 at a current density of 0.5 A g−1 and 179 F g−1 even at 50 A g−1 in the KOH electrolyte, and 152 F g−1 at 1 A g−1 in the ionic liquid electrolyte with a wide voltage range. Significantly, the assembled symmetric supercapacitor using the NCNF/RGO as electrode materials reaches a large energy density of 84.2 Wh Kg−1 at a power density of 1.0 kW kg−1, indicating its great potential application.

Humidity sensor based on heterogeneous CoTiO3/TiO2 film with vertically aligned nanocrystalline structure

Vertically aligned nanocrystalline films with heterojunctions have attracted much attention as gas sensors because they provide high efficient transport pathways for carriers and large surface area with high activity for adsorption. In this work, a heterogeneous CoTiO3/TiO2 film is prepared by radio frequency sputtering TiO2 on prefabricated CoTiO3 film with a post annealing process. The vertically aligned nanocrystalline surface is achieved by atom inter diffusion and growth competition of the two phases. The obtained CoTiO3/TiO2 film shows nano-columnar arrays structure with dominant (104) orientation. As a humidity sensor, the film shows ultra-high response with fast response/recovery and good stability. The response value reaches 157.23 to 95% relative humidity, which is 38 times that of the pristine CoTiO3 film. Such excellent sensing performance is attributed to the corporation of vertically aligned nanocrystalline surface, advanced hydrophilicity and uniformly distributed heterojunctions.

Multimodal porous and nitrogen-functionalized electrode based on graphite felt modified with carbonized porous polymer skin layer for all-vanadium redox flow battery

Novel nitrogen-functionalized multimodal porous graphite felt (GF) electrodes for all-vanadium redox flow batteries (VRFB) have been developed using a simple binder-free fabrication method. We synergistically combined a polymer of intrinsic microporosity (PIM), as a carbon and nitrogen precursor, with vapor-induced phase separation. The GF with a carbonized PIM skin layer showed a high surface area and multimodal pore architecture featuring interconnected micro-, meso-, and macropores. The enhanced electrochemical reactivity and wettability, and excellent electronic conductivity of the prepared electrodes successfully improved the overall kinetics of the redox reactions of the vanadium ion species by providing highly active catalytic sites and efficient ion and electron transport pathways. This resulted in the outstanding performance of VRFB single cells using this material as electrodes.

One-pot synthesis of SnS/C nanocomposites on carbon paper as a high-performance free-standing anode for lithium ion batteries

A novel and one-pot calcination method is applied for the fabrication of SnS nanoparticles coated by ultrathin carbon layer on carbon paper, resulting in a SnS/C-carbon paper free-standing electrode for lithium ion batteries. In this hierarchical structure, the carbon layer has dual function of buffering the volume change of SnS and anchoring SnS nanoparticles on the substrate compactly. Besides, it also can boost charge transfer kinetic in the electrode. Meanwhile, the carbon paper with three-dimensional structure allows for fully absorption of electrolyte and provides efficient transport pathways for electrons. Benefiting from these structure features, the binder-free SnS/C-carbon paper electrode exhibits excellent cyclability and delivers a reversible capacity of 696.2 mAh g−1 at a current density of 0.5 A g−1 after 200 cycles. Besides, SnS/C-carbon paper free-standing electrode achieves a reversible capacity of 562.3 mAh g−1 at a current density of 2.0 A g−1, demonstrating a promising rate ability which is significant for high power applicants. Such one-pot and novel route to synthesize SnS/C-carbon paper free-standing electrode with excellent electrochemical performance can pave the way for the development of low-cost and time-saving fabrication of free-standing anode for high-performance lithium ion batteries.

Hierarchical porous carbon materials from bio waste-mango stone for high-performance supercapacitor electrodes

Porous activated carbon was successfully fabricated from bio waste-mango stone via a two-step chemical etching strategy. The optimized carbon material (denoted as MGKZ-2) displayed a high specific capacitance of 353.8 F g−1 at 0.5 A g−1 and a satisfactory rate capability in the three-electrode supercapacitor system. Moreover, MGKZ-2-based symmetric cell presented a high energy density of 27.6 Wh kg−1 at 159.9 W kg−1, as well as long-term cycling stability due to its hierarchical pores to offer large ion-accessible surface area, efficient ion diffusion and electron transport pathways.

(Invited) One Dimensional Nanomaterials for Emerging Energy Storage

One-dimensional nanomaterials can offer large surface area, facile strain relaxation upon cycling and efficient electron transport pathway to achieve high electrochemical performance. Hence, nanowires have attracted increasing interest in energy related fields. We designed the single nanowire electrochemical device for in situ probing the direct relationship between electrical transport, structure, and electrochemical properties of the single nanowire electrode to understand intrinsic reason of capacity fading. The results show that during the electrochemical reaction, conductivity of the nanowire electrode decreased, which limits the cycle life of the devices. We have developed a facile and high-yield strategy for the oriented formation of CNTs from metal−organic frameworks (MOFs). The appropriate graphitic N doping and the confined metal nanoparticles in CNTs both increase the densities of states near the Fermi level and reduce the work function, hence efficiently enhancing its oxygen reduction activity. Then, we fabricated a field-tuned hydrogen evolution reaction (HER) device with an individual MoS2 nanosheet to explore the impact of field effect on catalysis. In addition, we demonstrated the critical role of structural H2O on Zn2+ intercalation into bilayer V2O5·nH2O. The results suggest that the H2O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2O5 framework, effectively promoting its diffusion. We also identified the exciting electrochemical properties (including high electric conductivity, small volume change and self-preserving effect) and superior sodium storage performance of alkaline earth metal vanadates through preparing CaV4O9 nanowires. Our work presented here can inspire new thought in constructing novel one-dimensional structures and accelerate the development of energy storage applications. L. Q. Mai, Y. J. Dong, L. Xu and C. H. Han. Nano Lett. 10, 4273 (2010). L. Q. Mai, M. Y. Yan and Y. L. Zhao, Nature. 546, 469(2017). J. S. Meng, C. J. Niu, L. H. Xu, J. T. Li, X. Liu, X. P. Wang, Y. Z. Wu, X. M. Xu, W. Y. Chen,Q. Li, Z. Z. Zhu, D. Y. Zhao and L.Q. Mai. J. Am. Chem. Soc. 139, 8212 (2017). J. H. Wang, M. Y. Yan, K. N. Zhao, X. B. Liao, P. Y. Wang, X. L. Pan, W. Yang, L. Q. Mai. Adv. Mater. 29 (2016 ). M. Y. Yan, P. He, Y. Chen, S. Y. Wang, Q. L. Wei, K. N. Zhao, X. Xu, Q. Y. An, Y. Shuang, Y. Y. Shao, K. T. Mueller, L. Q. Mai, J. Liu, and J. H. Yang. Adv. Mater. 1703725 (2017). X. M. Xu, C. J. Niu, M. Y. Duan, X. P. Wang, L. Huang, J. H. Wang, L. T. Pu, W. H. Ren, C. W. Shi, J. S. Meng, B. Song and L. Q. Mai. Nature Commun. 8, 460 (2017).

Microporous/mesoporous cobalt hexacyanoferrate nanocubes for long-cycle life asymmetric supercapacitors

Metal hexacyanoferrates with both microporosity and mesoporosity are highly desirable for supercapacitors because efficient transport pathways of metal ions can be provided by mesopores. Here, we have successfully synthesized microporous/mesoporous cobalt hexacyanoferrate (CoHCF) nanocube by tuning the molar ratios of reactants. The CoHCF nanocube is characterized by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption and electrochemical techniques. The results show that the K3[Fe(CN)6]/CoCl2 molar ratios have great influence on texture, morphology and electrochemical performance. The CoHCF nanocube with the average size of around 250 nm has a Brunauer–Emmett–Teller specific surface area of 572 m2 g−1. And the material possesses a specific capacitance as high as 441 F g−1 at 1 A g−1 in 1 M Na2SO4 electrolyte. In addition, an asymmetric supercapacitor is assembled by using the CoHCF nanocube as the positive electrode and activated carbon as the negative electrode. The device exhibits good supercapacitor performance with a specific capacitance of 61.8 F g−1 (1 A g−1) and an energy density of 12.9 Wh kg−1 (632 W kg−1). Long-term cycling stability tests demonstrate that the capacity retains 91% after 6000 charge–discharge cycles.

2D‐Layered MoS2‐Incorporated TiO2‐Nanofiber‐ Based Dye‐Sensitized Solar Cells

AbstractAtomically thin layers of molybdenum disulfide (MoS2) were examined to facilitate electron transport in titanium dioxide (TiO2) nanofiber network for dye sensitized solar cell (DSSC) applications. Raman active modes observed at 382 cm−1 and 406 cm−1 confirmed the presence of atomically thin MoS2 in TiO2 and transmission electron microscopic studies showed MoS2 with a lattice spacing of 3.12 Å. DSSCs using MoS2 incorporated TiO2 nanofiber as a photo‐anode resulted in 27% enhancement in photo‐conversion efficiency (η) than that of the DSSC using only TiO2 as an electron acceptor. A 26% enhancement in the short circuit current density (JSC) achieved by incorporating 0.1 weight % of MoS2 nanoflakes in the bulk of TiO2 confirmed efficient electron transport achieved by suppressing the probability of electron‐hole capture by TiO2 surface states due to the additional electron transport pathways established by MoS2 which facilitated the photo‐generated electrons to reach the transparent electrode by skipping the TiO2 surface states. Results suggest that further increase in the quantity of MoS2 in TiO2 impedes the electron transport in the bulk as observed with 7% and 38% reduction in η for 0.2 and 0.3 weight % of MoS2 in TiO2. This suggests that the DSSC performance can be increased for an optimum concentration of MoS2 in TiO2 by establishing efficient transport pathways towards the transparent electrode.

Scalable fabrication of ultrathin free-standing graphene nanomesh films for flexible ultrafast electrochemical capacitors with AC line-filtering performance

The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering have low specific capacitances, making them usually the largest components in electronic circuits. Herein, an ultrathin free-standing graphene nanomesh film (GMF) with uniform and dense nanoholes has been successfully fabricated by an in-situ carbothermal reduction strategy on the basis of spontaneously assembled graphene hybrid film. Due to the carbothermal reduction reaction between carbon atoms of graphene and the metal oxide nanoparticles in-situ generated during assembly process, in-plane nanopores are generated within graphene film. The pore size and density of GMF can be conveniently tuned by annealing temperature. With large ion-accessible surface area, efficient ion diffusion and electron transport pathways, the typical GMF-based electrochemical capacitor (EC) exhibits a high volumetric capacitance of up to 7.6 F cm−3 at 120 Hz, unprecedented power density of up to 3000 W cm−3, ultrafast frequency response with a phase angle of −82.3°, and a short resistor-capacitor time constant of 0.32 ms at 120 Hz, as well as long-term cycling stability. The performances of these ECs are superior to those of the state-of-the-art carbon-based ECs for this purpose; thus, it is promising to replace commercialized AECs for AC line-filtering in future electronics.

Scallop-Inspired Shell Engineering of Microparticles for Stable and High Volumetric Capacity Battery Anodes.

Building stable and efficient electron and ion transport pathways are critically important for energy storage electrode materials and systems. Herein, a scallop-inspired shell engineering strategy is proposed and demonstrated to confine high volume change silicon microparticles toward the construction of stable and high volumetric capacity binder-free lithium battery anodes. As for each silicon microparticle, the methodology involves an inner sealed but adaptable overlapped graphene shell, and an outer open hollow shell consisting of interconnected reduced graphene oxide, mimicking the scallop structure. The inner closed shell enables simultaneous stabilization of the interfaces of silicon with both carbon and electrolyte, substantially facilitates efficient and rapid transport of both electrons and lithium ions from/to silicon, the outer open hollow shell creates stable and robust transport paths of both electrons and lithium ions throughout the electrode without any sophisticated additives. The resultant self-supported electrode has achieved stable cycling with rapidly increased coulombic efficiency in the early stage, superior rate capability, and remarkably high volumetric capacity upon a facile pressing process. The rational design and engineering of graphene shells of the silicon microparticles developed can provide guidance for the development of a wide range of other high capacity but large volume change electrochemically active materials.

Three-dimensional amine-terminated ionic liquid functionalized graphene/Pd composite aerogel as highly efficient and recyclable catalyst for the Suzuki cross-coupling reactions

In this work, three-dimensional (3D) amine-terminated ionic liquid (IL) covalently functionalized graphene/Pd composite aerogels are successfully fabricated via a facile and green reduction-inducing self-assembly method. The morphology and composition of the obtained 3D IL-rGO/Pd composite aerogels are studied by means of TEM, SEM, XRD, FTIR, XPS, BET, and Raman spectroscopy. In those composites, the cations of NH2-IL introduced to the surface of graphene sheets can avoid the restacking of graphene sheets and enlarge the specific surface area, which provide efficient transport pathways for improving the catalytic performance. The negatively charged Pd precursors (PdCl42−) are adsorbed on positively charged imidazolium ring moiety of NH2-IL to engender Pd NPs with small particle sizes uniformly distributed on the graphene sheets, which can maximize the active surface area of catalysts and enhance their catalytic activity. The catalytic studies show that the 3D IL-rGO/Pd composite aerogels can be used as efficient, easy separation, recyclable, and stable catalysts for the Suzuki cross-coupling reactions under mild conditions, and the catalytic efficiency shows no obvious loss even after ten repeated cycles.

Three-dimensional N- and S-codoped graphene hydrogel with in-plane pores for high performance supercapacitor

Rationally designed electrodes with a high specific surface area, conductivity, and ion diffusion rate are essential for high performance supercapacitors. Hereby, we report the construction of a three-dimensional (3D) N- and S-codoped graphene hydrogel with abundant in-plane pores (NS-HGH). In NS-HGH, its highly interconnected network structure largely restrains the restacking of the graphene sheets, offering a specific surface area of as high as 317 m2 g−1. The abundant intimate graphene sheet-sheet contacts and in-plane pores created provide efficient electron transport pathways and ion transport pathways, respectively. The dopants of N and S heteroatoms further improve the porosity and conductivity of the resultant NS-HGH. With these characteristics, the NS-HGH electrode exhibits a high specific capacitance of 320.0 F g−1 at 1 A g−1 and retains 96.4% of the initial capacitance upon 10000 potential cycles at 10 A g−1. Whiles, the supercapacitors made from the NS-HGH electrodes deliver an impressive gravimetic energy density of 24.7 Wh kg−1 at 1 A g−1. To understand the high capacitive performance of the NS-HGH, we further performed first-principle simulations. It is revealed that heteroatom doping offers additional capacitance to NS-HGH because its density of states (DOS) near the Fermi energy level can be largely increased as a result of abundant polarized sites produced. These results suggest that NS-HGH shows great potential for practical application.

Hierarchical NiAl LDH nanotubes constructed via atomic layer deposition assisted method for high performance supercapacitors

Layered double hydroxides (LDHs) have attracted wide attentions in supercapacitor fields owing to their versatile physical and chemical properties. In this work, hierarchical NiAl LDH nanotubes consisting of ultrathin nanosheets were synthesized by integrating an atomic layer deposition (ALD) technique with a simple hydrothermal treatment. The present NiAl LDH has the unique structural features that offer large ion-accessible surface area and efficient ion transport pathways. The developed NiAl LDH nanotubes exhibit an excellent electrochemical performance including high specific capacitance, excellent rate performance and outstanding cycling stability as a battery-type electrode for supercapacitors. Thereinto, the 10NiAl-LDH-based electrodes can provide an initial specific capacitance of 2123.7Fg−1 at a current density of 0.5Ag−1, and 91.9% of the initial capacitance is retained after 10000 cycles at a current density of 5Ag−1. We believe that the excellent electrochemical performance for 10NiAl-LDH should mainly be ascribed to the appropriate Ni2+/Al3+ ratio, diameter of nanotubes and thickness of nanosheets determined by thickness of ALD Al2O3, and the detailed mechanism is discussed.

Fast charge rate supercapacitors based on nitrogen-doped aligned carbon nanosheet networks

Achieving high electrochemical energy density while retaining high power density still remains a great challenge for porous carbons as the electrodes for supercapacitors. We report a facile and scalable synthesis of N-doped aligned carbon nanosheet network (N-ACN10) with high surface area and efficient 3D ion and electron transport pathways. Moreover, 3D interconnected nanochannels parallel to the graphene planes are beneficial for the increased ion accessible surface area and fast ion diffusion. Benefiting from fast ion and electron transport kinetics, the N-ACN10 electrode exhibits excellent frequency response with a scan rate up to 5Vs−1, high capacitance of 331Fg−1 at 2mVs−1 and superior rate capability (203Fg−1 at 5Vs−1), as well as excellent cycling stability (98% of capacitance retention after 10,000 cycles) in 6M KOH. More importantly, the assembled N-ACN10//N-ACN10 supercapacitors exhibit outstanding electrochemical performances in 1M Na2SO4 and EMIMBF4 electrolytes with maximum energy densities of 20.6 and 120.4Whkg−1 based on the mass of total active material, respectively.

Silicon/polypyrrole nanocomposite wrapped with graphene for lithium ion anodes

ABSTRACTHerein, silicon nanoparticles (SiNPs) are coated with conducting hydrogel and wrapped with reduced graphene oxide (rGO) sheets via a facile and scalable solution-based sol-gel process. The in-situ polymerized polypyrrole (PPy) hydrogel forms an interconnected three-dimensional (3D) fiber matrix. Amine and hydroxyl groups from the hydrogel assist the encapsulation of the SiNPs through hydrogen bonding. The electro-conductive PPy fiber network and the wrapping of rGO offer efficient electron and ion transport pathways. The PPy/SiNPs/rGO electrodes can produce highly reversible capacities of 1312, 1285 and 1066 mAh g-1 at 100, 250 and 500 cycles at a current density of 2.1 A g-1, respectively.

One-Step Conversion from Core-Shell Metal-Organic Framework Materials to Cobalt and Nitrogen Codoped Carbon Nanopolyhedra with Hierarchically Porous Structure for Highly Efficient Oxygen Reduction.

Rational design of porous structure is an effective way to fabricate the nonprecious metal electrocatalysts (NPMCs) toward oxygen reduction reaction (ORR) with high activity comparable or even superior to Pt-based electrocatalysts. Herein, we demonstrate a facile synthetic route to fabricate cobalt and nitrogen codoped carbon nanopolyhedra with hierarchically porous structure (Co,N-HCNP) by one-step carbonization of core-shell structured ZIF-8@ZIF-67 crystals. The resultant Co,N-HCNP electrocatalyst possesses a unique hierarchically micro/mesoporous structure with internal micropores and external mesopores, of which sufficient exposure and accessibility of ORR active sites can be achieved due to the large specific surface area and efficient transport pathway. More importantly, the existence of ZIF-8 core in the core-shell structured ZIF-8@ZIF-67 can promote the homogeneous pyrolysis of ZIF-67 shell, leading to a uniform distribution of Co-Nx active sites for Co,N-HCNP. As a result, the well-designed Co,N-HCNP electrocatalyst exhibits remarkable ORR activity with a high onset potential comparable to the commercial Pt/C, a half-wave potential of 0.855 V (9 mV more positive than that of Pt/C), and a kinetic current density of 63.84 mA cm-2 at 0.8 V (2.3-fold enhancement compared with that of Pt/C) in alkaline electrolyte. Furthermore, the Co,N-HCNP electrocatalyst also presents outstanding electrochemical durability and methanol tolerance in comparison with Pt/C. The unique hierarchically porous structure of Co,N-HCNP achieved in this work provides a new insight into the design and synthesis of nanoarchitecture with targeted pore structure and opens a new avenue for the synthesis of highly efficient NPMCs for ORR.