Systematic Density Functional Theory Calculations Research Articles

Graphite-N reinforced sludge biochar electrode: A experimental and DFT theoretical analysis of efficient evolution and in-situ utilization of H2O2

Rational reuse of municipal sludge to produce electro-Fenton electrode can not only save resources, but also produce superior peroxide and degradation pollutants simultaneously. Herein, a novel electro-Fenton electrode derived from sludge biochar loaded on Ni foam (SBC@Ni) was constructed via high temperature pyrolysis and chemical coating for efficient H2O2 evolution and pollutant degradation. Systematic experiments and density functional theory calculations (DFT calculation) explained that the production of graphite C and graphite N during high-temperature pyrolysis of municipal sludge can greatly enhance the oxygen reduction reaction of SBC@Ni electrode and promote the evolution of H2O2. And the hybrid heterojunctions, such as FeP, also played a key role in electrocatalytic processes. Notably, the electrode still exhibited excellent performance after 1000 linear scans and 12 hours of continuous current stimulation, which demonstrated the excellent stability of the electrode. Moreover, SBC@Ni electrode can not only effectively oxidize 4-chlorophenol through the electro-Fenton effect, but also fully mineralize organic matter, indicating promising environmental application. The free radical quenching experiment also revealed that the ·OH is the main active species for 4-CP degradation in SBC@Ni electro-Fenton system.

Superconductivity in CH4 and [formula omitted] containing compounds derived from the high-pressure superhydrides

Inspired by the synthesis of the high-pressure Fm3̄m LaH10 superconducting superhydride, systematic density functional theory (DFT) calculations are performed to study ternaries that could be derived from it by replacing two of the hydrogen atoms with boron or carbon and varying the identity of the electropositive element. Though many of the resulting alkali-metal and alkaline-earth MC2H8 phases are predicted to be dynamically stable at mild pressures, their superconducting critical temperatures (Tcs) are low because their metallicity results from the filling of an electride-like band. Substitution with a trivalent element leads to phases with substantial metal d-character at the Fermi level whose Tcs are typically above 40 K. Among the MB2H8 phases examined, KB2H8, RbB2H8 and CsB2H8 are predicted to be dynamically stable at very mild pressures, and their stability is rationalized by a DFT-Chemical Pressure analysis that elucidates the role of the M atom size. Quantum anharmonic effects strongly affect the properties of KB2H8, the highest predicted Tc compound, near 10 GPa, but molecular dynamics simulations reveal it would decompose below its Tc at this pressure. Nonetheless, at ca. 50 GPa KB2H8 is predicted to be thermally stable with a superconducting figure of merit surpassing that of the recently synthesized LaBeH8.

Enhanced visible light photocatalytic performance of carbon and oxygen co-doped carbon nitride with a three-dimensional structure: Performance and mechanism study

As a cost-effective photocatalyst, carbon nitride (g-C3N4) holds tremendous promise for addressing energy shortages and environmental pollution. However, its application is limited by disadvantages such as low specific surface area and easy recombination of photogenerated electron-hole pairs. This study introduces C and O co-doped g-C3N4 with a three-dimensional (3D) structure achieved through a straightforward one-step calcination process, demonstrating excellent photocatalytic activity of hydrogen production and oxytetracycline degradation, with superoxide radicals as the primary active species. We propose a plausible enhanced mechanism based on systematic characterizations and density functional theory calculations. The 3D structure confers a substantial specific surface area, enhancing both the adsorption area and active sites of catalysts while bolstering structural stability. Co-doping optimizes the band structure and electric conductivity of the catalyst, facilitating rapid migration of photogenerated charges. The synergistic effects of these enhancements significantly elevate the photocatalytic performance. This study presents a convenient and feasible method for the preparation of dual-regulated photocatalysts with outstanding performance.

Enhanced electrocatalytic conversion of tellurium with MnO hollow nanospheres modified hierarchical n-doped carbon nanosheets in high-performance aqueous Zn-Te battery

Rechargeable aqueous zinc batteries (AZBs) are increasingly recognized as an alternative to conventional energy storage systems due to their environmentally safe nature, abundant zinc resources, and high theoretical capacity. However, the intercalation or surface redox mechanisms limit the development of AZBs cathode materials due to low specific capacity and energy density. The tellurium-based (Te) materials with conversion mechanisms are promising cathode materials for AZBs. Nevertheless, the slow kinetics are detrimental to the increase in specific capacity and energy density for Zn-Te battery. Therefore, a hierarchical structure of manganese oxide (MnO) hollow nanospheres loaded on nitrogen-doped carbon nanosheets (MnO@NC) was rationally designed and used as Te hosts (Te/MnO@NC) for Zn-Te battery. This hierarchical structure facilitates the loading of more Te species. Meanwhile, the MnO hollow nanospheres can expose more active sites, which can promote the kinetics of Te redox reactions thereby lowering the reaction energy barrier. The Te/MnO@NC cathode exhibits high specific capacity and high energy density (429 mAh g−1 and 407 Wh Kg−1 at 0.1 A g−1). Additionally, the conversion mechanism was investigated by systematic characterization and density functional theory (DFT) calculations. This study presents a new design platform for developing AZBs with high specific capacity and energy density.

Built-in electric field and selenium vacancies synergistically enhance NiSe2@Co0.85Se high-performance supercapacitors

Sluggish kinetics and poor cycling stability are two major obstacles limiting large-scale energy storage in battery-type supercapacitors. Herein, a novel strategy has been proposed to address these issues, which is to use a simple two-step electrodeposition technology to prepare the NiSe2@Co0.85Se/NF(denoted as NS@CS/NF) core-shell heterostructure, generate built-in electric field, and subsequently introduced anionic vacancies to successfully construct unique Se vacancies-rich composites (denoted as Sev-NS@CS/NF). Systematic characterisation analysis and density functional theory (DFT) calculations confirm that Se vacancies and heterogeneous interfaces can modulate electronic structure and promote fast reaction kinetics to achieve excellent supercapacitor performance, with a specific capacitance of 1530 C g−1 at 1 A g−1, and a capacity retention of 86.35% even after undergoing 10,000 charge-discharge cycles. Furthermore, a hybrid supercapacitor (HSC) was constructed using Sev-NS@CS/NF as the cathode and activated carbon (AC) as the anode, exhibiting an energy density of 80 Wh kg−1 at 812 W kg−1 and maintained impressive performance metrics. Notably, when two HSC units were connected in series, they successfully illuminated an LED diode for a duration of 15 min, showcasing the considerable potential of this HSC device for various energy storage applications.

Enhancing Metallicity and Basal Plane Reactivity of 2D Materials via Self-Intercalation.

Intercalation (ic) of metal atoms into the van der Waals (vdW) gap of layered materials constitutes a facile strategy to create materials whose properties can be tuned via the concentration of the intercalated atoms. Here we perform systematic density functional theory calculations to explore various properties of an emergent class of crystalline 2D materials (ic-2D materials) comprising vdW homobilayers with native metal atoms on a sublattice of intercalation sites. From an initial set of 1348 ic-2D materials, generated from 77 vdW homobilayers, we find 95 structures with good thermodynamic stability (formation energy within 200 meV/atom of the convex hull). A significant fraction of the semiconducting host materials are found to undergo an insulator to metal transition upon self-intercalation, with only PdS2, PdSe2, and GeS2 maintaining a finite electronic gap. In five cases, self-intercalation introduces magnetism. In general, self-intercalation is found to promote metallicity and enhance the chemical reactivity on the basal plane. Based on the calculated H binding energy, we find that self-intercalated SnS2 and Hf3Te2 are promising candidates for hydrogen evolution catalysis. All the stable ic-2D structures and their calculated properties can be explored in the open C2DB database.

Benzotrithiophene-based sp2 carbon-conjugated microporous polymers for green light-triggered oxidation of amines to imines

To optimize the activity at the molecular level, conjugated microporous polymers (CMPs) can be tailored through monomers for visible light photocatalysis. Benzotrithiophene (BTT) is the select monomer for CMPs because of its planar and electron-rich properties. Notably, the sp2-carbon conjugation of BTT is highly desirable to facilitate electron transfer. Herein, the condensation of 1,4-phenylenediacetonitrile and 4,4′-biphenyldiacetonitrile with benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde assembles two CMPs, sp2c-BTT-CMP-1 and sp2c-BTT-CMP-2, respectively. Systematic materials characterizations and density functional theory calculations on sp2c-BTT-CMP-1 and sp2c-BTT-CMP-2 are performed to interpret the essential optoelectronic attributes. Due to the different linkages and π-conjugations, sp2c-BTT-CMP-2 presents a better built-in electric field than sp2c-BTT-CMP-1, edging toward facile dissociation and fast transport of charge carriers. Consequently, sp2c-BTT-CMP-2 is superior to sp2c-BTT-CMP-1 for the green light-triggered oxidation of amines to imines with dioxygen. This study underlines the promising aspect of BTT-based CMPs with a fitting linkage as state-of-the-art functional materials for semiconductor photocatalysis.

Enhancing heat generation ability and magnetic properties of MgFe2O4 with Ni substitutes for biomedical applications

Herein, using the systematic experimental characterization and density functional theory calculations, the effects of Ni elemental substitution on the crystal structure, cation distribution, magnetic properties, and heat generation ability of Mg1–xNixFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) have been reported. We demonstrate that the presence of Ni can lead the lattice shrinkage, phase transition from partially to fully inverse spinel structure, and multi-domain structures in the samples. Moreover, Ni substitutional atoms make magnetically harder ferrite, associated with increasing magnetic inhomogeneity. Remarkably, anomalous enhancements of magnetic anisotropic and coercivity have been observed in Mg0.4Ni0.6Fe2O4. Heat generation ability (SAR) increases from 242 W g−1 for x = 0–391 W g−1 for x = 0.6 at an AC magnetic field of 370 kHz frequency. Thus, the magnetic hyperthermia of Mg0.4Ni0.6Fe2O4 sample on HeLa shows promising results that the viability of cells decreases to 25 % after 5 sessions. The present experimental and theoretical systematic studies provide novel avenue and paradigm for the development of ferrite nanoparticles with high heat generation ability and magnetic properties for biomedical applications.

Rational design of bidirectional electrocatalysts and accelerated sulfur redox reactions in lithium-sulfur batteries

Lithium–sulfur (Li–S) batteries have emerged as one of the most promising energy storage solutions. However, its commercial application still faces a significant challenge: the sluggish redox reaction kinetics of the reversible lithium polysulfide (LiPS) conversion process. The strategic design of cathode structures and electrocatalysts can help accelerate polysulfide conversion. In this study, systematic density functional theory (DFT) calculations predict that the incorporation of platinum (Pt) nanoparticles, as a model electrocatalyst, into biomass carbon materials can effectively promote the bidirectional conversion of polysulfides. Detailed kinetic analyses reveal that Pt-doped biomass carbon materials possess exceptional electrocatalytic abilities for Li2S nucleation and dissociation. These findings are further elucidated by ex situ X–ray photoelectron spectroscopy measurements, elucidating the bidirectional mechanism of Pt. The sulfur cathode delivers a remarkable specific discharge capacity of 1386.9 mAh g–1 at 0.1 C. Even more impressive is its potential for practical applications, exemplified by a high initial capacity of 1218.7/1015.3 mAh g−1 and excellent cycling stability under a high sulfur loading of 4.5/7.5 mg cm−2, which achieved substantial capacity retention (83.9/81.1%) after 100 cycles. This bidirectional electrocatalysis, achieved through the synergy of metal with biomass carbon materials, presents an attractive approach for advancing Li–S systems.

Non-Stoichiometric <i>fcc</i>-Base GdO<i><sub>x</sub></i> Precipitations in a Mg–Zn–Gd Alloy

We have found that, during in-situ scanning transmission electron microscopy observations, heating of a Mg97Zn1Gd2 (at.%) alloy at 623K leads to dynamic precipitations of face-centered-cubic (fcc)-based Gd nanoparticles. With the aid of density-functional theory (DFT) calculations, the observed lattice constant of 5.32 Å, which is larger than that expected for pure fcc-Gd of 5.06 Å, is likely to be due to oxygen atoms inserted at tetrahedral interstitial sites with essentially a fractional occupation. Systematic DFT calculations show that the fcc-base GdOx can be stable configurations in a wide composition range, where the O atoms behave like a solute up to x ~ 1.5 to provide continuously the non-stoichiometric GdOx solid-solution phase.

Dynamic Electronic and Ionic Transport Actuated by Cobalt-Doped MoSe2 /rGO for Superior Potassium-Ion Batteries.

Molybdenum selenium (MoSe2 ) has tremendous potential in potassium-ion batteries (PIBs) due to its large interlayer distance, favorable bandgap, and high theoretical specific capacity. However, the poor conductivity and large K+ insertion/extraction in MoSe2 inevitably leads to sluggish reaction kinetics and poor structural stability. Herein, Coinduced engineering is employed to illuminate high-conductivity electron pathway and mobile ion diffusion of MoSe2 nanosheets anchored on reduced graphene oxide substrate (Co-MoSe2 /rGO). Benefiting from the activated electronic conductivity and ion diffusion kinetics, and an expanded interlayer spacing resulting from Co doping, combined with the interface coupling with highly conductive reduced graphene oxide (rGO) substrate through Mo-C bonding, the Co-MoSe2 /rGO anode demonstrates remarkable reversible capacity, superior rate capability, and stable long-term cyclability for potassium storage, as well as superior energy density and high power density for potassium-ion capacitors. Systematic performance measurement, dynamic analysis, in-situ/ex-situ measurements, and density functional theory (DFT) calculations elucidate the performance-enhancing mechanism of Co-MoSe2 /rGO in view of the electronic and ionic transport kinetics. This work offers deep atomic insights into the fundamental factors of electrodes for potassium-ion batteries/capacitors with superior electrochemical performance.

Broad-bandgap porous graphitic carbon nitride with nitrogen vacancies and oxygen doping for efficient visible-light photocatalytic degradation of antibiotics

Effective degradation methods are required to address the issue of antibiotics as organic pollutants in water resources. Herein, a two-stage thermal treatment method was used to prepare porous graphitic carbon nitride (g-C3N4) modified with nitrogen vacancies and oxygen doping at the N–(C)3 position and deep in the g-C3N4 framework. Compared with bulk g-C3N4 (BCN) (7 ± 1 m2/g), the modified sample (RCN-2h) possesses a larger specific surface area (224 ± 1 m2/g), a larger bandgap (by 0.19 eV), and a mid-gap state. In addition, RCN-2h shows 15.4, 11.2, and 9.5 times higher photodegradation rates than BCN for the degradation of 100% ofloxacin (OFX) (within 15 min), tetracycline (within 15 min), and sulfadiazine (within 35 min), respectively. The RCN-2h catalyst also exhibits superior stability and reusability. Systematic characterization and density functional theory calculations demonstrate that the synergistic effect of the porous structure, nitrogen vacancies, and oxygen doping in RCN-2h provides additional reaction sites, improved charge separation efficiency, and shorter diffusion paths for reactants and photogenerated charge carriers. Trapping experiments reveal that •O2− is the main active species in OFX photodegradation, and a possible photodegradation pathway is identified using liquid chromatography–mass spectrometry. Benefiting from the simplicity of synthesis methods and the superiority of elemental doping, carbon nitride materials with functional synergy have great potential for environmental applications.

Adsorption performance and mechanisms of MgO-modified palygorskite/biochar composite for aqueous Cd (II): Experiments and theoretical calculation

The treatment of Cd2+ pollution in water has been a hot topic of research, while the studies for the preparation and application of biochar composites to treat Cd2+ and the corresponding micro-mechanisms were still lacking. In this study, a novel MgO-modified palygorskite/biochar derived from rice straw composite (MPBC) was synthesized to remove Cd2+ in the aqueous solution. Batch experiments were conducted to evaluate the adsorption ability for Cd2+ on MPBC. The results showed that the maximum adsorption capacity of MPBC was 441.1 mg/g, which was 4.6 times higher than that of the original biochar (BC). Adsorption mechanisms were clarified combine systematic characterization and density functional theory (DFT) calculations. Precipitation, complexation, ion exchange, and Cd-π interaction were the main adsorption mechanisms, and the contribution of the ion exchange, compared with 12.08% of BC, increased to 37.82%. The O atom of the MgO group performed negative electrostatic potentials as an electrophilic active site. The nucleophilic Cd tends to transfer electrons to the electrophilic O atom of the MgO group. Furthermore, the density of state (PDOS) identified that hybrid overlap occurred between MgO and Cd, and a new chemical bond was formed in the adsorption process. Overall, this work offers a new approach to removing aqueous Cd2+ and uses biowaste to create a sustainable environment.

Rational construction of S-scheme Pt-MnO2/TiO2@Ti3C2Tx via Ti-O-Mn bond for distinguished charge transfer in photocatalytic wastewater environmental governance and hydrogen production

Exploring and adjusting the migration pathway of photogenerated electron-hole pairs in novel semiconductor composites is vital to enhance the charge separation efficiency and transferability in photocatalytic environmental governance and hydrogen generation performance. Herein, an electrostatic self-assembly combining with a low-temperature hydrothermal strategy for forming the Ti-O-Mn bond was designed to rationally construct the S-scheme Pt-MnO2/TiO2@Ti3C2Tx composite. Through the systematic characterization and density functional theory calculations, the metastable marginal Ti atoms and the electrostatic adsorbed Mn2+ ions on Ti3C2Tx surface are oxidized and in situ form TiO2/MnO2 nanoparticles (NPs) due to its fitted lattice energy and low adsorption energy, which are intercalated on the conductive Ti3C2Tx multilayer surfaces and construct a new-fashioned S-scheme TiO2/MnO2 heterojunction via the Ti-O-Mn bond, for affecting the density of charge states, promoting the charge separation and shortening migration carrier distance. Also, Pt NPs as the cocatalyst is selectively decorated on MnO2/TiO2@Ti3C2Tx surface for further improving the charge carrier transfer and visible light absorption. Benefiting from the extraordinary composition and structure, the obtained Pt-MnO2/TiO2@Ti3C2Tx composite exhibits high photocatalytic degradation of organic pollutants (more than 90%), hydrogen generation activity (3610 μmol g−1 h−1) and wonderful cycle stability.

The efficient degradation of high concentration phenol by Nitrogen-doped perovskite La2CuO4 via catalytic wet air oxidation: Experimental study and DFT calculation

Herein, N-doped perovskite La2CuO4 (LCO) (N-LCO(M)) was fabricated by sol–gel rapid calcination method using melamine (M) as N source/ligand, and applied for the catalytic wet air oxidation (CWAO) to degrade high-concentration phenol-containing simulated wastewater. The experimental results exhibited that N-LCO(M) illustrated enhanced phenol degradation efficiency. Thereinto, 87.9% COD degradation efficiency was achieved in simulated wastewater containing 8000 mg/L phenol, while for undoped LCO prepared with citric acid (CA) as ligand (LCO(CA)) was only 43.8%. The systematic characterizations and density functional theory (DFT) calculations were utilized to verify the above results. The results revealed that N doping favored the formation of more oxygen vacancies (*) and facilitated the charge transfer between Cu and O. More oxygen vacancies (*) reinforced the ability of N-LCO(M) to adsorb O2 to form reactive oxygen species (O*), and meanwhile, the charge transfer between Cu and O was manifested as the redox cycle of the catalytic active metal Cu2+/Cu1+. The redox cycle also promoted the formation of O2− and HO, making the more exhaustive degradation of phenol. This successfully proved that N doping was core to improving the activity and stability of N-LCO(M). Moreover, a possible mechanism of phenol degradation was proposed based on the experimental results and DFT calculations. Eventually, the toxicity of the intermediate products was further evaluated by quantitative structure–activity relationship (QSAR) analysis, showing the significantly reduced toxicity of the intermediate products. Overall, the proposed CWAO technique is a green and promising wastewater treatment method.

Ferroelectric control of magnetic anisotropy of 5d transition metal monolayers

Electric field control of magnetism using ferroelectric materials offers promising applications in low-power spintronics. We have conducted systematic density functional theory calculations to investigate the magnetic properties of epitaxial $5d$ transition metal monolayers on a ferroelectric substrate: $\mathrm{PbTi}{\mathrm{O}}_{3}$ (PTO). Our study reveals that the magnetocrystalline anisotropy energy of the osmium monolayer is significantly enhanced to 18.1 meV/Os in the upward polarization state and, moreover, the anomalous Hall coefficient of osmium/PTO film is tunable by reversing the electric polarization of the PTO substrate. Additionally, the electric polarization reversal in PTO rotates the easy magnetization axis of the iridium and platinum monolayers by ${90}^{\ensuremath{\circ}}$, which is attributed to the rearrangement of interfacial charges. Our findings suggest an efficient approach to control the magnetization direction of monoatomic layers and provide valuable insights for the development of low-energy spintronics devices.

Cooperation between Dual Metal Atoms and Nanoclusters Enhances Activity and Stability for Oxygen Reduction and Evolution

We have achieved the synthesis of dual-metal single atoms and atomic clusters that co-anchor on a highly graphitic carbon support. The catalyst comprises Ni4 (and Fe4) nanoclusters located adjacent to the corresponding NiN4 (and FeN4) single-atom sites, which is verified by systematic X-ray absorption characterization and density functional theory calculations. A distinct cooperation between Fe4 (Ni4) nanoclusters and the corresponding FeN4 (NiN4) atomic sites optimizes the adsorption energy of reaction intermediates and reduces the energy barrier of the potential-determining steps. This catalyst exhibits enhanced oxygen reduction and evolution activity and long-cycle stability compared to counterparts without nanoclusters and commercial Pt/C. The fabricated Zn-air batteries deliver a high power density and long-term cyclability, demonstrating their prospects in energy storage device applications.

Understanding Li interaction in TiO2/graphene composites for high-performance Li-ion battery anodes: A first principles study

Composite materials consisting of TiO2 and graphene (TiO2/GR) have exciting properties that could make them suitable as anode material for Li-ion batteries. Systematic density functional theory (DFT) calculations were performed to investigate the TiO2/GR energy-storage mechanism, adsorption sites and diffusion pathways of Li ions in TiO2/GR. Its interface and the region outside graphene were studied for identifying stable surface sites. The adsorption energies are dominated by van der Waals interactions. Li diffusion along the graphene plane was the most favorable with a diffusion energy barrier of 0.24 eV, whereas the probability of diffusion at the interface is low, due to the barrier of 3 eV. The composite exhibited a higher specific charge-storage capacity than other van der Waals heterostructures. The TiO2/GR interface retains a large amount of charge implying that the TiO2/GR composite shows suitable electrochemical properties for use as anode in lithium-ion batteries.

Catalytic multivariable metal-organic frameworks for lithium-sulfur batteries

Metal-organic frameworks (MOFs) hold potential for promoting the redox reaction of sulfur species (RRS) and suppressing the shuttle effect in lithium–sulfur batteries (LSBs). However, except for a limited number of frameworks, most MOFs are found to be inert in accelerating RRS, which is largely related to the fact that their design principles and mechanism of catalysis have not been fully understood. Systematic density functional theory (DFT) calculations and experimental results reveal that the lack of exposed polar catalytic sites restricts MOF’s potential in promoting RRS. Herein, based on a series of multivariable MOFs containing ligands with different thermal stability, selective ligand removal and ligand exchange (LE) strategies were applied successively to expose the catalytic metal clusters and introduce extra adsorption sites, rendering inert MOFs into catalytic ones. Such post-modified multivariable MOFs were shown to yield LSBs with remarkably improved specific capacity and cycling stability realizing 7.9 mAh cm−2 of capacity after 100 cycles at high sulfur loading of 8.1 mg·cm−2 under a lean electrolyte condition. The universal strategy proposed in this work will guide the design of catalytic MOFs for RRS and promote the development of advanced catalysts for high-performance LSBs.

Co–Pyridinic-N Bond Constructed at the Interface of CoxP and N-Doped Carbon to Effectively Facilitate Oxygen Reduction

The construction of bonding interfaces between cobalt-base phosphides and N-doped carbon is considered an effective means to promote ORR catalytic performance. However, the role of different nitrogen configurations in promoting the ORR performance of cobalt-base phosphides is currently unknown. Herein, the honeycomb-like CoxP@N-doped carbon catalyst was constructed to systematically investigate the effect of different nitrogen configurations on improving the catalytic performance of CoxP. Systematic experimental investigations and density functional theory (DFT) calculations indicate that the interaction of Co with pyridinic-N not only regulates the atomic Co coordination environment but also induces strong orbital hybridization between N-p orbitals and Co-d orbitals, significantly increasing the electron density on pyridinic-N sites, which greatly increases the attraction to oxygen-containing intermediates and lowers the reaction energy barrier, thus promoting the catalytic activity for ORR. Furthermore, honeycomb morphology not only reduces the internal diffusion resistance of reactants and products as well as the relative concentration of surface reactants but also exposes more accessible active sites and increases the contact area with the electrolyte, thus greatly enhancing the oxygen reduction reaction. As expected, the as-prepared catalyst exhibits ultrahigh ORR activity with a half-wave potential of 0.88 V, which is superior to that of the noble metal Pt and most previously reported non-noble metal catalysts. This study perfectly explains why cobalt-base phosphide embedded in N-doped carbon can improve its ORR catalytic performance.