Cation Vacancies Research Articles

Hydrothermal-Induced Cationic Vacancies in NiAl Hydroxide for Enhanced Oxygen Evolution Activities through Optimization of eg* Band Broadening.

Nickel-based hydroxides [Ni(OH)2] have attracted significant attention as effective oxygen evolution reaction (OER) catalysts. In recent years, defect engineering has been extensively utilized in Ni(OH)2 modification research. Numerous studies have confirmed that the generation of defects can expose more active sites and regulate electronic states, particularly through the introduction of Al cationic vacancies, which enhance conductivity and thereby improve the catalytic performance. The traditional method for producing cationic vacancies is electrochemical etching. However, this method generates a limited number of vacancies in the catalysts and has the complex etching process. Herein, we found that when NiAl layered double hydroxides were treated using a hydrothermal process at 100 °C in a KOH solution, more Al cationic vacancies were generated. Compared to the traditional method with an Al leaching efficiency of 24%, our proposed method achieved an Al leaching efficiency of 44%. Meanwhile, the electrochemical results showed that the overpotential was reduced by 110 mV at 10 A/g. Further experiments showed that the enhanced OER activities resulting from an increased number of cationic defects lead to structural distortions, which broaden the eg* band, significantly affecting the rate of electron transfer between the electrocatalyst and external circuitry, thereby enhancing the OER activity. This work presents a promising approach to creating cationic defects in Ni(OH)2 for high-performance electrocatalysts.

P-Type AgAuSe Quantum Dots.

Control over the carrier type of semiconductor quantum dots (QDs) is pivotal for their optoelectronic device applications, and it remains a nontrivial and challenging task. Herein, a facile doping strategy via K impurity exchange is proposed to convert the NIR n-type toxic heavy-metal-free AgAuSe (AAS) QDs to p-type. When the dopant reaches saturation at approximately 22.2%, the Femi level shifts down to near the valence band, with the p-type carrier characteristics confirmed through photoluminescence, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy analysis. First-principles calculations reveal that K impurities preferentially occupy interstitial positions and form complex defects when combined with the abundant cationic vacancy in AAS caused by the high mobility of Ag, thereby functioning as a shallow acceptor to enhance p-type conductivity. A p-n homojunction based on AAS QDs has been fabricated and served as the active layer in a photodiode device, which demonstrates an excellent room-temperature detectivity of up to 2.29 × 1013 Jones and an outstanding linear dynamic range of over 103 dB. This study provides guidance for future design of the p-n homojunction using the toxic-metal-free Ag-based QDs and further unleashes their potential in advanced optoelectronic device applications.

Creating Cation Vacancies in BiOCl Nanosheets Toward Exceptional Visible-Light-Driven Photocatalytic CO2 Reduction.

BiOCl-based materials have emerged as promising photocatalysts for converting CO2 into valuable products and fuels. However, challenges such as low light absorption and inefficient charge carrier separation require effective solutions, with vacancy engineering offering a promising approach. Current research primarily focuses on anion vacancies, leaving cation vacancies less explored. In contrast, this study presents a novel method to enhance visible-light-driven photocatalysts by Bi cation vacancies in ultrathin BiOCl nanosheets through a straightforward hydrochloric acid etching process (HAE-BiOCl). These introduced Bi vacancies not only expand the light absorption range and enhance carrier separation, but also serve as active sites for CO2 adsorption. Additionally, Bi vacancies can effectively lower the activation energy of COOH- species and thereby enhance overall reaction activity. As a result, the HAE-BiOCl catalyst exhibits exceptional photocatalytic CO2 reduction performance without the need for co-catalysts or sacrificial agents. It achieves high CO generation rates of 68.39 and 17.43µmol g-1 h-1 under 300W Xe lamp and visible light irradiation, respectively. These rates are significantly higher compared to counterparts without vacancy creation and surpass those of most reported Bi-based photocatalysts. This study underscores the potential of inducing cation vacancies via acid etching as a valuable strategy for advancing photocatalysis.

Cation Vacancy-Mediated Ultrafast Hole Transport in CuBi2O4 Photocathodes.

In this study, the ultrafast transport dynamics of the valence band hole states in CuBi2O4 (CBO) photocathodes were investigated by varying the atomic composition and manipulating their p-type character. As a comprehensive ultrafast optical transient absorption spectroscopy (TAS) investigation of compositionally manipulated CBO that combines both ex situ and in situ TAS experiments with photoelectrochemical (PEC) performance tests, the study reveals the polaron formation tendencies of the valence band (VB) holes at cationic vacancy sites. Therefore, it draws a complete picture of the ultrafast hole transport dynamics and provides valuable insights into the hindrance of the photocurrent generated in CBO.

The mechanical and dielectric properties of high-density Ti-doped MgAl2O4 ceramic prepared by non-hydrolytic sol-gel combined with mechanochemical method

The synthesis of MgAl2O4 requires high calcination temperatures which generally result in larger grain sizes and smaller specific surface areas. These factors pose challenges in achieving high-density MgAl2O4 ceramic. This study introduces an innovative approach that has successfully sintered MgAl2O4 ceramic at 1500 ℃ with MgAl2O4 powder prepared using a Non-Hydrolytic Sol-Gel (NHSG) method combined with a mechanochemical method. The sintered MgAl2O4 ceramic with 2 wt% TiCl4 doping displays an apparent porosity of only 0.09 %, a flexural strength of 183 MPa, a relative permittivity of 8.7, a quality factor of 77000 GHz, and a frequency temperature coefficient of −59.4 ppm/℃. The introduction of titanium ions causes lattice distortion and cationic vacancies, which promotes sintering and improves the mechanical and dielectric properties of the resulting ceramic. This study demonstrates the effectiveness of NHSG combined with the mechanochemical method in preparing MgAl2O4 ceramic with enhanced sintering properties.

Enhancing electrode efficiency by tuning surface electronic properties and defects in NiFe layered double hydroxide nanosheets with Al or Zn cation vacancies

Layered double hydroxides (LDHs) containing transition metals have emerged as promising electrode materials for supercapacitors due to their low cost, strong redox activity, and environmental friendliness. In this study, we propose a novel approach by creating Zn-defect Zn(II) engineered D-NiFeZn-LDHs through cyclic voltammetry etching in an alkaline solution of NiFeZn-LDHs synthesized on a carbon cloth substrate. This defect engineering increases electrochemical active sites and improves ion diffusion within the layered structure. The D-NiFeZn-LDHs demonstrate an impressive specific capacitance of 1204.8 F g⁻1 at 1 A g⁻1 and retain 61.52 % of their initial capacity after 10,000 cycles at 10A g⁻1, showcasing excellent long-term cycling stability. Moreover, the all-solid-state asymmetric supercapacitor constructed using D-NiFeZn-LDHs delivers a high energy density of 31.63 Wh kg⁻1 at 125 W kg⁻1 and retains 65.95 % of its capacity after 5000 cycles at a high current density of 10 A g⁻1. These findings provide a new strategy for developing high-performance energy storage materials.

Photoluminescence and afterglow of Yb2+ doped CaAl2O4

The photoluminescence (PL) and afterglow properties of Yb2+ doped CaAl2O4 phosphors (0–2.0×104 ppm) are investigated. The 4f14–4f135d1 transitions of Yb2+ dopant are evidenced by a number of sharp lines in the excitation and emission spectra of Yb2+ doped CaAl2O4. As a contrast, the host emission of Yb2+ doped CaAl2O4 is characteristic of a broadband PL spectrum which can be deconvoluted into three overlapped subbands: an ultraviolet subband peaking at 3.30 eV (375.8 nm), a blue subband peaking at 2.81 eV (441.3 nm) and a green subband peaking at 2.35 eV (527.7 nm). The afterglow spectrum of Yb2+ doped CaAl2O4 consists of three discrete subbands: an ultraviolet subband centered at around 3.54 eV (350 nm), a blue subband centered at around 2.82 eV (440 nm) and a green subband centered at about 2.30 eV (540 nm). Depending on their intensities of the afterglow subbands, the perception color of the afterglow of Yb2+ doped CaAl2O4 evolves from blue to green, and the afterglow of Yb2+ doped CaAl2O4 lasts for 86 min at the optimal doping level of 20 ppm. Our results demonstrate that: (i) the ultraviolet and the blue afterglow subband of the phosphor originate from oxygen and cation vacancies in CaAl2O4; (ii) the green afterglow (PL) subband of Yb2+ doped CaAl2O4 originates from Mn2+ impurity in CaAl2O4; and (iii) instead of a luminescence center of afterglow, Yb2+ works as a luminescence center of PL and sensitizes CaAl2O4 by enhancing the ultraviolet light harvesting efficiency of the host.

Utilizing cationic vacancies to enhance nickel-cobalt layered double hydroxides for efficient electrocatalytic urea oxidation reaction

Electrocatalytic urea oxidation reaction (UOR) is a promising approach for urea-rich wastewater splitting, which benefits for reducing energy consumption in hydrogen production accompanying environmental protection and sustainable energy development. To address the limitations posed by the self-oxidation of nickel-based catalysts on the activity of UOR, we here developed a NiCo LDH nanosheet catalyst with abundant Ni vacancies to initiate the UOR process prior to nickel oxidation. Electrochemical impedance spectroscopy and In-situ spectroscopic characterizations confirm that the UOR process primarily occurs on the surface of the catalyst, rather than being driven by nickel oxidation products. The favorable electronic structure modulation induced by Ni vacancies makes the catalyst more energetically favorable for the UOR compared to nickel self-oxidation. The catalyst exhibits excellent UOR activity, only requiring 1.27 V vs. RHE at 10 mA cm−2 and 1.34 V vs. RHE at 100 mA cm−2, with no significant decay observed after over 120 h of operation. Furthermore, it can function as a bifunctional catalyst, requiring only 1.66 V to achieve 100 mA cm−2 for the UOR||HER system. This study expands the pathway for the application of cationic vacancies in UOR.

Unveiling the effect of bovine serum albumin on the corrosion resistance of high nitrogen stainless steel for cardiac stents

Herein, the effect of bovine serum albumin (BSA) on the corrosion resistance of high nitrogen stainless steel (HNS) is systematically investigated based on experimental characterizations and first-principle calculations. Electrochemical measurements firstly prove that the anodic dissolution rate of HNS has significantly increased due to BSA adsorption and the potential deterioration of the passive film. By subsequent morphology and composition characterizations, it is demonstrated that BSA forms a 1.9 μm porous adsorption layer on HNS surface via the peptide bond mostly in -helix and -turn structure. Furthermore, Mott-Schottky tests confirm that the carrier (cation vacancy) density in the passive film has dramatically risen from 6.29×1021 cm-3 to 1.97×1022 cm-3 after BSA adsorption, which could be ascribed to the detachment of Cr atom from its original lattice due to the preference interaction between BSA molecule and Cr atom. Most importantly, such an increased defects will further promote the dissolution process of both the passive film and HNS matrix according to point defect model (PDM), which will definitely undermine the protective ability of the passive film and eventually result in the declined corrosion resistance of HNS in BSA-contained solution.

Surface charge rearrangement modulation of N, P co-doped carbon induced by iron-cobalt phosphide with cationic vacancies for efficient contaminant removal

Surface charge rearrangement modulation of N, P co-doped carbon induced by iron-cobalt phosphide with cationic vacancies for efficient contaminant removal

Investigating base-catalyzed aldol condensation reactions on alkali-free hydrotalcites and the role of thermal decomposition

Aldolization is a crucial carbon–carbon coupling reaction used in the conversion of biomass-derived platform molecules into valuable chemicals and fuels. In this work, we combine experiment and theory to explore the role thermal decomposition has in controlling the structure of alkali-free Mg-Al layered double hydroxides (LDHs) and their subsequent performance in the base-catalyzed aldol condensation of acetone, focusing on the constituent aldolization and dehydration steps. LDHs were synthesized via co-precipitation and subjected to calcination at temperatures up to 600 °C to produce mixed metal oxides of the form Mg3AlOz which were further examined by SEM, N2 physisorption, XRD, and CO2-TPD. Aldolization and dehydration behaviors were examined in a batch reactor and fit with kinetic models to capture the sensitivities of both reactions to calcination temperature. Additional experiments involving the selective blocking of base sites by CO2 poisoning and reversal at varying temperatures showed that both aldolization and dehydration are likely driven by the strongest base sites, yielding a site density (0.19 μmol m−2) in agreement with separate propionic acid titration studies. Density functional theory (DFT) simulations of Mg5Al2O8 surfaces were employed to gain microscopic insights into these materials, revealing the importance of Al substitution in creating cation vacancies which can drive aldol condensation through enolate intermediates stabilized in the oxyanion resonance form. High-coverage simulations of the surface show participation of the vacancy in both aldolization and dehydration, rationalizing the coupling of rate trends observed experimentally. Ultimately, this study provides new insights and approaches useful in the design of heterogeneous aldolization catalysts.

Tailoring Cationic Cobalt Vacancies in Molybdenum-Cobalt Selenide Derived from POM@ZIF-67 for Enhanced Electrocatalysis in Lithium-Oxygen Batteries.

Slow reaction kinetics during redox reactions limits the utilization of the high theoretical energy density of lithium-oxygen batteries (LOBs). Vacancy engineering, a potential strategy for modulating active sites, is critical in the development of high performance catalysts. This study investigates cobalt vacancies in Mo-CoSe2 nanoparticles created by selenization of phosphomolybdic acid (POM) embedded into zeolitic imidazolate framework-67 (ZIF-67). The nanomaterial exhibits an outstanding electrochemical performance, characterized by high specific capacitance and excellent cycle durability. The LOBs with cobalt vacancies in the Mo-CoSe2 electrode material exhibit a discharge capacity of 21 836 mAh g-1 at a current density of 100 mA g-1 and exhibit stable cycling performance over 194 cycles at 300 mA g-1. Additionally, density functional theory (DFT) calculations suggest that the presence of cobalt vacancies increases the distance between the surface selenium atoms and the subsurface cobalt atoms. In addition, cobalt vacancies modify the electronic structure of the d-orbitals, lowering the energy barriers of the reaction and accelerating the reaction kinetics by improving the adsorption of the reactants. The research introduces a strategy for the rational design of efficient cathode materials in LOBs.

Realizing Ultrahigh Conversion Efficiency of ≈9.0% in YbCd2Sb2/Mg3Sb2 Zintl Module for Thermoelectric Power Generation.

Recently, YbCd2Sb2-based Zintl compounds have been widely investigated owing to their extraordinary thermoelectric (TE) performance. However, its p orbitals of anions that determined the valence band structure are split due to crystal field splitting that provides a good platform for band manipulation by doping/alloying and, more importantly, the YbCd2Sb2-based device has yet to be reported. In this work, single-phase YbCd1.5Zn0.5Sb2 is successfully obtained through precise chemical composition control. Then, YbMg2Sb2-alloying increases the cationic vacancy defect formation energy and further optimizes carrier concentration. Moreover, the band structure of YbCd1.5Zn0.5Sb2 is subtly manipulated, and the underlying mechanism is experimentally explored. Combined with the reduced lattice thermal conductivity, a high peak ZT value of ∼1.43 at 700K is obtained for YbCd1.425Zn0.475Mg0.1Sb2. Subsequently, choosing Fe90Sb10 as the diffusion barrier layer and adopting the transient liquid phase bonding technique, for the first time, it is demonstrated that YbCd2Sb2/Mg3(Sb, Bi)2 TE module with an ultrahigh conversion efficiency of ≈9.0% at a heat difference of 430K. More importantly, this module displays good thermal stability. This work paves the way for YbCd2Sb2 materials and devices in mid-temperature heat recovery.

Modifying the buried interface by a sulfamate enable efficient perovskite solar cells with high stability

The buried interface between the pivotal perovskite layer and the electron transfer layer (ETL) greatly affects the photoelectric property of perovskite layer and the final performance of a perovskite solar cell (PSC). Effectively modifying the buried interface is feasible to improve the photoelectric conversion efficiency (PCE) and stability of PSCs. Herein, we employ a sulfamate sodium 4-aminoazobenzene-4′-sulfonate (SABS) with zwitterion to modify the SnO2 film surface to improve the performance of PSCs. The post-treatment makes the surface of SnO2 film smoother and also passivate the anion and cation vacancies of SnO2, which are benefit to the growth of perovskite crystals and strengthen the interface contact between SnO2 layer and perovskite layer. Furthermore, SABS molecules can passivate defects of perovskite layer at the buried interface. By using this post-treating method, the PCE of the final PSC is increased from 21.76 % to 23.86 %, and the storage and operational stability are also significantly improved. This promotion the buried interface via post-treating the SnO2 film with a zwitterion passivator provides a convenient strategy to effectively improve the performance and stability of PSCs.

Defect-Enabled Superior Negative Thermal Quenching in Palmierite Ba9La(VO4)7:Eu3+ for WLED In Situ Temperature Measuring.

Negative thermal quenching (NTQ) of the phosphors is critically important for both scientific research and practical applications, but the design of efficient NTQ phosphors is still a challenging task. Herein, we report a new strategy for developing NTQ materials by cation-vacancy engineering. Specifically, a new color-tunable Ba9La1-x(VO4):xEu3+ (BLVO:xEu3+) phosphor with abundant intrinsic cation vacancy was developed, exhibiting superior NTQ behavior under 365 nm excitation. The NTQ performance can be modulated via adjusting Eu3+ doping levels, and the emission intensity of Eu3+ ions in the BLVO:0.20Eu3+ phosphor increased by 275% at 473 K compared to room temperature. Furthermore, the reported material emitting bright white light under 365 nm excitation was well-suited for use in white light-emitting diode (WLED) phosphor and fluorescent temperature sensors, exhibiting outstanding color-rendering index (90.1) in lighting and high sensitivity (Sa = 11.83% K-1, Sr = 2.33% K-1) in temperature detecting. Lastly, the operating temperature of WLED at different currents can be monitored and displayed in real time through emission spectroscopy. All of the results demonstrated that the designed NTQ BLVO:xEu3+ can be used as a single-phase white phosphor and optical thermometry. This work provides a fresh perspective for designing high-efficient NTQ phosphors and expands the application of phosphors in WLED in situ temperature detection.

Excess Energy Released Due To Proton-Proton Collisions in Condensed Matter Could Be Due To Laboratory-Made Micro Black Holes

While sodium metal dissolution in concentrated (2M) Epsom solution is very peaceful under stirring conditions in about 5 to 10s, its dissolution in a dilute (0.85) Epsom solution has turned very violent. Nearly 30s after the addition of Na, the solution exploded accompanied by the vaporization of the glass beaker. Only sodium aerosol and tiny molten needles of glass were seen around indicating a very high temperature (>1000 0C) has indeed been reached. The timing of the explosion has indicated that hydrogen released during sodium dissolution has got trapped in the salt solution and subsequent energy build-up has caused the excess energy release. A viable trapping mechanism involving the exchange of 2 hydrogen ions (H22+) with an Mg2+ ion in cavitation-induced nanocrystals of Epsom has been proposed in this regard. The two hydrogen ions are stabilized at the cation vacancy (cavity) by dative bonds with the two hydrogen ions in the water molecule trapped at a neighboring sulphate vacancy. Spring-like action between the two protons trapped at the cation vacancy due to oscillations caused by two opposing forces – one by cavitation and the other by coulombic repulsion eventually appear to have led to the collision of hydrogen ions at relativistic speeds in condensed matter. To start with, the two protons in the H22+ species are confined in a small space (72 pm cavity) at a single crystal cation lattice site in Na2SO4 nanocrystal which increases their head-on collision probability at high energies. There is no upper limit to the energies achieved through p-p collisions in this species as the Cavitation-Coulombic Repulsion Oscillations (CCRO) can continue until the endpoint is reached. Regeneration of a nanocrystal over a sufficiently small time scale and regeneration effect prior to cavitation collapse are all important so laws of thermodynamics are not violated. Extra dimensions of gravity at short distances, if present, could also assist in the high energies required for the production of mini black holes in condensed matter. Such black holes lose mass very quickly through the emission of Hawking radiation observed in the form of explosion with mass-energy equivalence of E = mc2. The possibility of tapping such explosive energy for peaceful purposes is discussed. As such it constitutes the third kind of atomic energy humans have entertained, the first two being fission and fusion.

Mn2+ doped aluminum-rich spinel transparent ceramic phosphor with higher performance for wide color-gamut backlight display

Due to the great potential of narrow-band green-emitting phosphors for wide color-gamut white light-emitting diodes (WLED) backlight displays, there is great interest in finding host materials with the desired luminescent properties and high quantum efficiency. Herein, a series of Mg0.98-xAl2(1+x/3)O4: 0.02Mn2+ (x = 0, 0.125, 0.25) powders were synthesized using high-temperature solid-phase reactions, followed by a combination of pressureless sintering and hot isostatic pressure sintering to fabricate transparent ceramic phosphors. The crystal structure refinement, NMR spectroscopy, and photoluminescence results show tetrahedral coordination of Mn2+ ions and an increase in cation vacancies and disorder with increasing x. These transparent ceramics exhibit narrow-band green emission, which shifts from 523 to 520 nm with increasing x. The Mg0.855Al2.08O4: 0.02Mn2+ ceramic sample has an in-line transmittance of over 80 % above 500 nm and internal quantum efficiencies as high as 96.2 %. The luminous intensity of the Mg0.855Al2.08O4: 0.02Mn2+ ceramic remains above 88.6 % at 425 K compared to room temperature, with a thermal conductivity of 12.4 W·m−1·K−1. A WLED device fabricated using the Mg0.855Al2.08O4: 0.02Mn2+ ceramic, K2SiF6:Mn4+ phosphors, and a blue chip show a wide color gamut of 126 % National Television System Committee standard. The results show that Mn2+-doped aluminum-rich spinel transparent ceramics have great potential for application in wide color gamut WLED backlight devices.

Origin of magnetism via cation vacancy defects in non-stoichiometric NiCo2O4 nanoparticles: A synchrotron-based x-ray absorption and x-ray magnetic circular dichroism spectroscopic study

The present study probes the effect of cation distributions in the structural, optical, electronic, and magnetic properties of mixed-valent inverse-spinel NiCo2O4 (NCO) nanoparticles (NPs). NCO NPs were prepared using the sol–gel combustion method and the grain size was obtained in the magnetic exchange length range assumed to be from single-ion anisotropy. The Raman and photoluminescence spectroscopies confirm the presence of an inverse-spinel structure with different oxidation states, and vibrating sample magnetometry clarifies the existence of ferromagnetism with the presence of magnetic anisotropy among the cations. These NPs annealed at a higher grain-growth temperature accumulate ferrimagnetic properties and produce magneto-crystalline anisotropy making NCO an assuring material for spintronic applications. A detailed x-ray absorption spectroscopy and x-ray magnetic circular dichroism studies reveal an indestructible correlation between the distribution of the present cations and the element-specific origin of ferrimagnetic behavior. Ni is found to be accountable for the magnetic moment and electronic conduction, whereas Co is associated mainly with the generation of the magnetic anisotropy even in the polycrystalline NP form. This describes the anti-ferromagnetic coupling between Co and Ni ions that is pivotal in demonstrating the exchange interaction between these cations. The above result signifies the site-dependent cation valence states for the magnetic properties, and the extent of growing conditions are related to such cation-site dysfunction. This depicts further tunability in NCO as a functional oxide material.

Quaternary Mixed Oxides of Non-Noble Metals with Enhanced Stability during the Oxygen Evolution Reaction.

Robust electrocatalysts required to drive the oxygen evolution reaction (OER) during water electrolysis are still a missing component toward the path for sustainable hydrogen production. Here a new family of OER active quaternary mixed-oxides based on X-Sn-Mo-Sb (X = Mn, Fe, Co, or Ni) is reported. These nonstoichiometric mixed oxides form a rutile-type crystal structure with a random atomic motif and diverse oxidation states, leading to the formation of cation vacancies and local disorder. The successful incorporation of all cations into a rutile structure was achieved using oxidizing agents that facilitates the formation of Sb5+ required to form the characteristic octahedral coordination in rutile. The mixed oxides exhibit enhanced stability in both acidic and alkaline environments under anodic potentials with no changes in their crystal structure after extensive electrochemical stress. The improved stability of these mixed oxides highlights their potential application as scaffolds to host and stabilize OER active metals.

Selection of high rate capability and cycling stability MnO anode material for lithium-ion capacitors: Effect of the carbon source

The N-doped carbon modified MnO composites were successfully prepared using K2MnO4 as the manganese source, CH4N2O as the nitrogen source, and glucose, sucrose, or reduced graphene oxide as the carbon sources. Among them, the composite (MPN) prepared using glucose as the carbon source exhibited excellent electrochemical performance, attributed to its relatively small particle size (6.4 nm), high specific surface area of 199.4 m2·g−1, and a high ID/IG ratio of 0.86. The MnO in MPN contained a significant amount of Mn3+, ∼16.8 %, which is ascribed to the incomplete reduction of high valence Mn during the process of synthesis. With the formation of Mn3+, a large number of cationic vacancies were generated, which increased the diffusion coefficient of Li+ from 2.12 × 10−14 cm2 s −1 to 5.94 × 10−13 cm2 s−1. The carbon layer with appropriate thickness, doped N and mesoporous structure suitable for electrolyte transport provide a fast ion/electron transport channels for MnO, and ensure a stable interface structure in the electrochemical reactions. Consequently, the MPN anode material exhibited remarkable high current discharge capacity (769.5 mAh·g−1 at a high current density of 2 A·g−1) and excellent cycling performance (882.2 mAh·g−1 after 200 cycles at 1 A·g−1), indicating its exceptional rate performance and cycle stability. Furthermore, the lithium ion capacitor constructed with MPN as anode and activated carbon as cathode demonstrated a high specific energy of 190 Wh·kg−1, a high specific power of 205.3 W·kg−1, and an impressive cycling lifespan of up to 3000 cycles without obvious degradation.