Multivalent Mn Research Articles

Fiber temperature sensor based on dual-wavelength emitting Mg0.388Al2.408O4: Mn2+/Mn4+ phosphors for real-time temperature monitoring

Single doped Mg0.388Al2O3.408O4 phosphor was prepared and multivalent Mn ion (Mn2+ and Mn4+) emission was achieved in a single host. The structure, morphology, and luminescence characteristics of Mn ions in Mg0.388Al2O3.408O4 were discussed in detail, especially the temperature dependent emission characteristics of Mn ions. Based on the fluorescence intensity ratio (FIR) of Mn2+versus Mn4+ and the decay lifetime of Mn4+ emission as the temperature readout, a dual-mode optical temperature-sensing mechanism was proposed and studied in the temperature range of 293–473 K. The maximum relative sensitivities (Sr) are derived as 2.83 % K−1 (at 373 K based on FIR) and 3.40 % K−1 (at 473 K based on decay lifetime), respectively. The temperature sensing characteristics of Mg0.388Al2.408O4: Mn2+/Mn4+ powders in a full fiber system were studied, which can provide thermal-sensitive emissions at dual-wavelengths for stable ratiometric temperature sensing with good precision and repeatability. The constructed all fiber temperature sensing system has been applied in the on-line monitoring of CPU temperature.

Enhancing Photoreduction of Cr(VI) through a Multivalent Manganese(II)-Organic Framework Incorporating Anthracene Moieties.

Exploiting a photocatalyst with high stability and excellent activity for Cr(VI) reduction under mild conditions is crucial yet challenging. Herein, the rigid aromatic multicarboxylate ligand with chromophore anthracene was selected to coordinate with multivalent metal ion manganese and to obtain a stable two-dimensional (2D) Mn-based metal-organic framework (MOF), LCUH-120, which can efficiently and quickly convert Cr(VI) into Cr(III) under light without the need for any additional photosensitizer. The efficient photosensitive anthracene group serves as a photosensitizer center and multivalent Mn(II) ion as a photocatalyst center in LCUH-120, and the conversion of Cr(VI) to Cr(III) can be realized completely in just 40 min. Specifically, the rate constant (k) and reduction rate of the Cr(VI) photocatalytic reaction can be high up to 0.134 min-1 and 2.50 mgCr(VI) g-1cata min-1 in an acidic environment (pH = 2), respectively. Compared to our previously reported three-dimensional (3D) Sm-MOF, LCUH-120 exhibits a significantly higher catalytic reaction rate, which might be ascribed to the fact that the photocatalyst center Mn node can improve the rate of electron transfer and promote the separation of holes and photogenerated electrons. In an acidic environment, the reaction mechanism can be verified through various contrast experiments and theoretical simulations.

Surface Engineering Enhances Vanadium Carbide MXene-Based Nanoplatform Triggered by NIR-II for Cancer Theranostics.

Despite the advantages of high tissue penetration depth, selectivity, and non-invasiveness of photothermal therapy for cancer treatment, developing NIR-II photothermal agents with desirable photothermal performance and advanced theranostics ability remains a key challenge. Herein, a universal surface modification strategy is proposed to effectively improve the photothermal performance of vanadium carbide MXene nanosheets (L-V2C) with the removal of surface impurity ions and generation of mesopores. Subsequently, MnOx coating capable of T1-weighted magnetic resonance imaging can be in situ formed through surface redox reaction on L-V2C, and then, stable nanoplatforms (LVM-PEG) under physiological conditions can be obtained after further PEGylation. In the tumor microenvironment irradiated by NIR-II laser, multivalent Mn ions released from LVM-PEG, as a reversible electronic station, can consume the overexpression of glutathione and catalyze a Fenton-like reaction to produce ·OH, resulting in synchronous cellular oxidative damage. Efficient synergistic therapy promotes immunogenic cell death, improving tumor-related immune microenvironment and immunomodulation, and thus, LVM-PEG can demonstrate high accuracy and excellent anticancer efficiency guided by multimodal imaging. As a result, this study provides a new approach for the customization of 2D surface strategies and the study of synergistic therapy mechanisms, highlighting the application of MXene-based materials in the biomedical field.

Transforming Plain LaMnO3 Perovskite into a Powerful Ozonation Catalyst: Elucidating the Mechanisms of Simultaneous A and B Sites Modulation for Enhanced Toluene Degradation.

Herein, we propose preferential dissolution paired with Cu-doping as an effective method for synergistically modulating the A- and B-sites of LaMnO3 perovskite. Through Cu-doping into the B-sites of LaMnO3, specifically modifying the B-sites, the double perovskite La2CuMnO6 was created. Subsequently, partial La from the A-sites of La2CuMnO6 was etched using HNO3, forming novel La2CuMnO6/MnO2 (LCMO/MnO2) catalysts. The optimized catalyst, featuring an ideal Mn:Cu ratio of 4.5:1 (LCMO/MnO2-4.5), exhibited exceptional catalytic ozonation performance. It achieved approximately 90% toluene degradation with 56% selectivity toward CO2, even under ambient temperature (35 °C) and a relatively humid environment (45%). Modulation of A-sites induced the elongation of Mn-O bonds and decrease in the coordination number of Mn-O (from 6 to 4.3) in LCMO/MnO2-4.5, resulting in the creation of abundant multivalent Mn and oxygen vacancies. Doping Cu into B-sites led to the preferential chemisorption of toluene on multivalent Cu (Cu(I)/Cu(II)), consistent with theoretical predictions. Effective electronic supplementary interactions enabled the cycling of multiple oxidation states of Mn for ozone decomposition, facilitating the production of reactive oxygen species and the regeneration of oxygen vacancies. This study establishes high-performance perovskites for the synergistic regulation of O3 and toluene, contributing to cleaner and safer industrial activities.

Significantly enhanced OER and HER performance of NiCo-LDH and NiCoP under industrial water splitting conditions through Ru and Mn bimetallic co-doping strategy

High-performance electrocatalysts play a crucial role in promoting the development of industrial water splitting. Reasonable electronic structure design is key to improving the performance of electrocatalysts. This study proposed a Ru and Mn bimetallic co-doping strategy to achieve rational electronic structure design of both NiCo-LDH (RMNCL) and NiCoP (RMNCP). Specifically, we first obtained Ru and Mn bimetallic co-doped NiCo-LDH through a one-step electrodeposition, exhibiting superior catalytic activity (342 mV at 500 mA/cm2) for the oxygen evolution reaction in alkaline solution. Subsequently, we prepared Ru and Mn co-doped NiCoP by a simple phosphorization treatment of RMNCL, demonstrating impressive low overpotentials (200 mV at 500 mA/cm2) for hydrogen evolution reaction in alkaline solution. Furthermore, we constructed an anion exchange membrane electrolyzer using the prepared catalysts, achieving a high current density of 1 A/cm2 with only 2 V, maintaining stability over a prolonged 100 h duration. Further studies revealed the highly dispersed Ru atoms provided abundant active sites, while Mn modified the electron filling of anti-bonding orbitals in both catalysts, optimizing reactant adsorption. Additionally, multivalent Mn contributed to the improved catalytic performance. This study provides insights into rational electrocatalyst design and lays the foundation for catalyst development with outstanding activity under industrial-scale conditions.

Robust Room Temperature Thermoelectric Performance of Mg3(Sb, Bi)2‐Based Alloys via Multivalent Mn Doping

Abstractn‐type Mg3(Sb, Bi)2 has excellent room temperature thermoelectric performance, which is, however, severely restricted by the negatively charged Mg vacancies that significantly deteriorate the carrier mobility. Herein, by manipulating the threshold solubility and defect formation energy of Mn, multivalent Mn is selectively introduced that synergistically promotes the carrier conduction according to different Mg chemical potentials; In Mg‐rich areas, interstitial Mn dominates which effectively reduces the migration and accumulation of Mg vacancies, while in Mg poor areas, interstitial Mn switches to substitutional sites that directly compensate for the negative charge. All the Mn centers possess Jahn–Teller inactive positions, leading to an ultra‐stable room temperature thermoelectric performance with a leading ZT up to 0.97. This work reveals the critical effect of multivalent and multifunctional transition metal incorporation in Mg3(Sb, Bi)2‐based alloys toward high room‐temperature thermoelectric performance.

Biomass-based 3D micro-meso-macroporous carbon for hybrid-capacitance characteristics and incredible energy density: Reversible charge transfer of multivalent Mn ions

To achieve the coordination of energy density and power density, the metal oxide (MnO2) that endow pseudo-capacitance in 3D porous carbon can build high energy density and specific capacitance at high-power density. Here we have showed the synthetization of a composites (JSPCC-MnO2) with a specific capacitance of 310.6 F/g, an energy density of 42.4 Wh/kg, and a power density of 1425 W/kg. The percentage of pseudo-capacitance caused by the element Mn is 31.17 %, the pseudo-capacitance process of the JSPCC-MnO2 has involved reversible charge transfer from Mn (II) to Mn (IV) to achieve high specific capacitance and energy density via multiple charge transfer dynamics. And the 3D micro-meso-macro porous structure has provided the electrolyte sufficient active sites and smooth ion migration channels. Atomic-scale information has been provided by classical molecular dynamics. In polarized states, the non-polar water molecular layer is at a higher energy level, and the electrostatic adsorption force between carbon atom and K ion is higher than the hydrophobic force of carbon. The loading MnO2 has disturbed the density distribution in the local region, changed the ordered structure, and made the loading sites form defects. Green, affordable and renewable biomass has been used as the precursor achieving the high energy density of the carbon-based electrode.

Investigation of the dynamic interaction between dopants and oxygen vacancies in amorphous Nb2O5: Simulation and experimental study

Resistive random-access memory can potentially be used to construct high-speed, low-power, and high-density data-storage drives. Managing oxygen flow at the electrode-oxide interface is vital for improving endurance. Dopant-oxygen interactions govern ion diffusion and vacancy creation. The interactions between multivalent dopants and oxygen vacancies in Nb2O5 have been investigated in previous studies. In this study, we simulated the relationship between a multivalent dopant Mn and oxygen vacancies in amorphous Nb2O5. We introduced oxygen vacancies and Mn ions with different oxidation states to determine the effects of spin densities and band gaps. Experimental results obtained from deposited amorphous thin films validated the simulation results, demonstrating a close agreement between the experimentally obtained (1.11 eV) and predicted bandgaps (0.93 eV). The results of study illuminate the amorphous structure of Nb2O5, the interactions between multivalent Mn dopants and oxygen vacancies, and the resulting electronic properties, offering the potential for designing and optimizing functional materials.

La0.8Sr0.2Mn0.8Co0.2O3-δ perovskite as an efficient functional electrocatalyst for oxygen reduction reactions

The negative effects of the widespread and rough use of fossil energy have promoted the emergence of new energy technologies. Cost-effective electrocatalysts play an irreplaceable role in energy conversion and storage, especially oxygen reduction reactions (ORR) catalysts. While the reserves of precious metal catalysts are rare and expensive, it is of prime importance to develop catalysts that can replace precious metals. In the present work, La0.8Sr0.2Mn0.8Co0.2O3-δ (LSMC) with Mn and Co is successfully prepared by sol-gel method and subsequent calcination. The characterizations of physical phase, microstructure, BET and valence state of elements demonstrate that LSMC material possesses ample mesoporous structure, large specific surface area, and multivalent elements, which can provide abundant active sites for ORR. The electrochemical tests reveal that the LSMC delivers outstandingly higher electrocatalytic activity for ORR, relatively lower overpotential and Tafel slope and a better long-term stability than the other perovskites (LSM, LSC) under alkaline condition. Furthermore, the coupling effects of high content of high-valence Co, multivalent Mn and large amounts of adsorbed oxygen endow the catalyst excellent ORR electrocatalytic activity. The present work investigating the effect of Mn and Co elements on the electrocatalysis of LSMC perovskite, will provide the possibility of developing a new type of perovskite electrocatalyst with excellent ORR electrocatalytic activity and low cost.

Efficient degradation of 2,3,5-trimethylpyrazine by catalytic ozonation over MnOx supported on biochar derived from waste tea leaves

In this study, a series of biochars derived from waste tea leaves and loaded with MnOx (Mn-nWT) was fabricated for use in heterogeneous catalytic ozonation (HCO). Excellent degradation of 2,3,5-trimethylpyrazine (TMP) was achieved. Characterization data indicated that Lewis acid sites, including multivalent Mn sites, oxygen vacancies and surface hydroxyl groups, were the main active sites responsible for the HCO activity of Mn-nWT. The Mn-nWT catalysts exhibited superior HCO activity compared with bulk biochar and MnOx under various experimental conditions. In particular, 0.05 g L−1 Mn-5WT gave 95.3% degradation of 5 μM TMP in 30 min at pH 7.0. Reactive oxygen species (mainly •OH) generated from catalytic decomposition of ozone by Mn-nWT contributed to the enhanced HCO performance. The second-order degradation rate constants of TMP with O3 and •OH are 2.3 ± 0.13 and (7.3 ± 1.31) × 109 M−1 s−1. The reusability and stability of Mn-5WT was demonstrated by outstanding TMP degradation efficiency (88.8%), negligible metal dissolution and minor differences in physical characterization after four cycles. Additionally, the impacts of water matrices (catalyst dose, ozone dose, pH, temperature, carbonate and natural organic matter) on the Mn-5WT HCO process were investigated thoroughly. This study found that loading of metal oxides onto biochar synergistically promoted the HCO process by enhancing the physical and chemical properties.

The promotional roles of multivalent metal ions and oxygen vacancies on nitrogen-doped carbon-combined CuMn-based catalysts for cyclohexylbenzene oxidation

In this work, we fabricated nitrogen-doped carbon (NC)-combined CuMn-based catalysts derived from layered double hydroxide and melamine mixture precursor and further explored their activity in the aerobic oxidation of cyclohexylbenzene (CHB) to produce cyclohexylbenzene-1-hydroperoxide (CHBHP) using molecular oxygen as the oxidant. Series of structural characterizations demonstrated that multivalent Cu and Mn species and abundant surface defective oxygen vacancies could form in catalysts, due to comprehensive redox processes between Cu and Mn atoms upon high-temperature calcination of precursors under inert atmosphere, as well as the promotional effect of melamine added on the reduction of metal ions. As-fabricated NC-combined CuMn catalyst bearing a 1:1 Cu:Mn molar ratio showed a higher catalytic oxidation activity, in comparison to other NC-decorated CuMn-based catalysts, NC-free CuMn-based one, and pure single metal oxides (i.e., CuO, MnO2). It was revealed that the presence of favorable multivalent Cu and Mn ions and abundant oxygen vacancies was conducive to the effective adsorption and activation of CHB and oxygen molecules, thus accelerating the selective oxidation of CHB to form CHBHP. Moreover, surface NC overlayer on catalysts could protect surface structures of catalysts during the oxidation. The present study provides deep understanding of the roles of surface-active metal species and oxygen vacancies of CuMn-based catalysts for efficient oxidation of CHB to form CHBHP.

Magnetic Photocatalysts Based on Nanocrystalline Manganese-Doped Titanium Dioxide

Manganese-doped anatase with a nanosized morphology (as spherically shaped nanoparticles) has been synthesized under hydrothermal conditions. It has been shown that manganese is incorporated into the titanium dioxide structure to form substitutional solid solutions. At high dopant concentrations, part of the introduced manganese goes to the formation of α-MnO2. A significant increase in the optical activity in the visible range and a decrease in the bandgap width down to ~2.4 eV are observed for manganese-doped anatase because of the appearance of extrinsic (multivalent Mn ions) and intrinsic compensating (oxygen vacancies) defects. It has been found that manganese-doped samples are diluted magnetic semiconductors, and the magnetic characteristics increase with increasing manganese content. All manganese-containing samples demonstrate photocatalytic activity in the degradation reaction of indigo carmine when irradiated with visible light. The degree of dye degradation depends on the content of manganese in the samples and reaches 90%.

A three-step process of manganese acquisition and storage in the microalga Chlorella sorokiniana.

Metabolism of metals in microalgae and adaptation to metal excess are of significant environmental importance. We report a three-step mechanism that the green microalga Chlorella sorokiniana activates during the acquisition of and adaptation to manganese (Mn), which is both an essential trace metal and a pollutant of waters. In the early stage, Mn2+ was mainly bound to membrane phospholipids and phosphates in released mucilage. The outer cell wall was reorganized and lipids were accumulated, with a relative increase in lipid saturation. Intracellular redox settings were rapidly altered in the presence of Mn excess, with increased production of reactive oxygen species that resulted in lipid peroxidation and a decrease in the concentration of thiols. In the later stage, Mn2+ was chelated by polyphosphates and accumulated in the cells. The structure of the inner cell wall was modified and the redox milieu established a new balance. Polyphosphates serve as a transient Mn2+ storage ligand, as proposed previously. In the final stage, Mn was stored in multivalent Mn clusters that resemble the structure of the tetramanganese-calcium core of the oxygen-evolving complex. The present findings elucidate the bioinorganic chemistry and metabolism of Mn in microalgae, and may shed new light on water-splitting Mn clusters.

Efficient activation of peroxymonosulfate by MnS/Fe-MOF hybrid catalyst for sulfadiazine degradation: Synergistic effects and mechanism

In this work, MnS/Fe-MOF composites were synthesized by a mild one-pot method and employed as efficient activators of peroxymonosulfate (PMS) for sulfadiazine (SDZ) removal in water. The surface morphology and structure of MnS/Fe-MOF was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, flourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. As expected, the as-prepared MnS10/Fe-MOF presented complete SDZ degradation within 30 min in the presence of 0.2 g/L catalyst and 0.6 mM PMS, which was better than those with Co2S/Fe-MOF, CoS/Fe-MOF and MoS2/Fe-MOF as well as other reported catalysts. The effects of experimental conditions, co-existing anions and humic acid on catalytic performance of MnS/Fe-MOF were also investigated. Moreover, OH, SO4−, O2− and 1O2 were evidenced to participate in the activation process using quenching experiments and electro-spin resonance spectrometer. The results of XPS analysis of MnS10/Fe-MOF before and after the reaction confirmed the synergistic effects between multivalent Mn, Fe and S species in MnS/Fe-MOF, which was beneficial for the rapid Mn+1/Mn+ (M stands for Fe and Mn) recycling. This is the first work expounding the facile synthesis method of MnS/Fe-MOF composites and its synergistic mechanism as an efficient PMS activator for the degradation of antibiotics.

A non-specific surface area dominated catalytic ozonation with CuO modified β-MnO2 in efficient oxalic acid degradation

In this paper, a series of copper oxide supported manganese dioxide (CuXMnT) composites were prepared by the hydrothermal and deposition precipitation methods. The effects of different hydrothermal temperatures (100 °C–180 °C) and copper doping amounts (1–10 mM) on the structural and physicochemical properties of CuXMnT composites were systematically investigated. The BET, SEM, and XRD characterizations revealed that the CuXMnT composites exhibited a typical rod-like structure. Besides, with the increscent hydrothermal temperature, the BET specific surface area decreased and the crystal form of the composites changed from α-MnO2 to β-MnO2. The Cu1Mn180 with low specific surface area (3.277 m2 g−1) exhibited the splendid catalytic ozonation activity and the oxalic acid (OA) removal rate reached 87.5% in O3/Cu1Mn180 process compared with single ozonation (3.2%). Additionally, it was noteworthy that the excellent catalytic performance of Cu1Mn180 (91.8% of OA removal rate) at pH 3.0 was resulted from the electrostatic adsorption. While, the complexation played a vital role for OA degradation at pH 6.0 and 9.0 with the OA removal efficiencies of 87.5 and 70.3% within 30 min, respectively. Furthermore, Cu1Mn180 could obtain more than 90.9% of OA removal rate during multiple consecutive cycles, representing the satisfactory stability and reusability. Moreover, the multivalent Mn, the structural oxygen species, and Cu species played the key roles for OA degradation in O3/Cu1Mn180 process at pH 6.0 via the TEM, ESR, XPS and O2-TPD characterizations. Overall, the results presented a promising alternative material for efficient catalytic ozonation application in water.

Persistent luminescence induced by the introduction of multi-valent Mn ions in K2LiBF6 (B = Al, Ga and In) fluoride phosphors

Mn4+ – activated elpasolite fluorides K2LiBF6 (B = Al, Ga and In) are well-known red-emitting phosphors for white light emitting diodes (WLEDs) application. Such fluorides exhibit narrow emissions at around 630 nm under near ultraviolet (NUV) or blue excitations, but in this work, we introduced an unusually broad emission band in the green to orange region under NUV excitation at low temperature by introducing impurity to the elpasolite structure. The nature of this photoluminescence (PL) has been verified to be from Mn2+ species, so we observed the multi-valence of Mn ions (Mn2+ and Mn4+) in fluorides, which is rarely discussed in literatures. Besides, the influence of Mn2+ on Mn4+ was studied in samples with different Mn4+/Mn2+ ratios. The configuration-coordinate model and crystal theory were employed to help us to get a deeper understanding that the presence of Mn2+ affects the stretching vibration mode ν2 of Mn4+ in octahedra. Furthermore, the thermal quenching of Mn2+ and Mn4+ was studied for ratiometric optical thermometer application. In addition, persistent luminescence (PersL) was found in the proposed fluorides. For example, Under NUV irradiation, white PL was achieved in K2LiGaF6: Mn, and the emission turned to the green once excitation ceased. We herein demonstrated a novel multi-valence synthetic method for dual-color emitting elpasolite fluorides and propose a mechanism for the observation of white PL and green PersL based on the multi-valence properties.

Fermi level pinning in Co‐doped BaTiO3: Part I. DC and AC electrical conductivities and degradation behavior

AbstractWe explore the synergistic effects of co‐doping BaTiO3 with a judicious combination of acceptors and donors to control the point defect chemistry and electrical properties, with the goal of simultaneously limiting the electronic and ionic conductivities over broad temperature and oxygen partial pressure (pO2) ranges. Specifically, we compare the temperature‐ and pO2‐dependent electrical properties of BaTiO3 ceramics acceptor‐doped with either Mn or Mg and co‐doped with a Y donor. This study, which is the first of a two‐part series, presents the electrical properties as a function of pO2, temperature, and time, focusing on the grain‐interior electrical response. The DC and AC electrical conductivity measurements reveal that co‐doping with Mn and Y can result in (1) increased electrical resistivity over a broad temperature range, (2) pO2‐independent electrical conductivity in oxidizing conditions, and (3) improved time‐dependent dielectric degradation resistance. These behaviors are attributed to a Fermi level pinning effect, as is explained in the companion paper, which presents complementary density functional theory (DFT)‐based grand‐canonical defect chemistry models. The collective experimental and computational studies demonstrate that the pO2‐independent electrical conductivity in the Mn and Y co‐doped BaTiO3 is attributed to a Fermi level pinning mechanism arising from the multivalent Mn dopant, and the background reservoir of positive charge provided by the predominant substitution of Y on the Ba sites. The enhanced degradation resistance is attributed to a reduced oxygen vacancy concentration relative to the other doping chemistries.

Unraveling the Role of CeO2 in Stabilization of Multivalent Mn Species on α-MnO2/Mn3O4/CeO2/C Surface for Enhanced Electrocatalysis

Unraveling the Role of CeO₂ in Stabilization of Multivalent Mn Species on α-MnO₂/Mn₃O₄/CeO₂/C Surface for Enhanced Electrocatalysis

The influence of Mn doping on the leakage current mechanisms and resistance degradation behavior in lead zirconate titanate films

The electrical reliability of lead zirconate titanate (PZT) films was improved by incorporating Mn; the time dependent dielectric breakdown lifetimes and the associated activation energy both remarkably increased with Mn concentration. The correlation between the defect chemistry and the resistance degradation was studied to understand the physical mechanism(s) responsible for enhanced electrical reliability. At lower electric fields, Poole-Frenkel emission was responsible for the leakage current. Beyond a threshold electric field, Schottky emission controlled the leakage. After electrical degradation of a 2 mol.% Mn doped PZT film, no significant change in potential barrier height for injecting electrons from the cathode into the anode was observed. This suggests that the degradation is mostly controlled by Poole-Frenkel conduction via some combination of hole migration between lead vacancies, small polaron hopping between Mn sites, and hole hopping between Pb2+ and Pb3+. No variation in the valence state of Ti near the cathode was observed in degraded Mn doped PZT films, implying that multivalent Mn provides trap sites for electrons and holes; free electron generation due to compensation of oxygen vacancies at the cathode and free hole formation at the anode region might be suppressed by the valence changes from Mn3+ to Mn2+ and Mn2+ to Mn3+ respectively.

Electrochemical sensor based on the Mn3O4/CeO2 nanocomposite with abundant oxygen vacancies for highly sensitive detection of hydrogen peroxide released from living cells.

Based on the strategy of increasing the number of oxygen vacancies to improve the catalytic performance, we have developed a novel electrochemical sensor based on the multivalent metal oxides cerium dioxide and manganous oxide (Mn3O4/CeO2) for reliable determination of extracellular hydrogen peroxide (H2O2) released from living cells. The Mn3O4/CeO2 nanocomposite was characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical performance of the Mn3O4/CeO2 nanocomposite modified glassy carbon electrode (Mn3O4/CeO2/GCE) was investigated. Owing to the abundant oxygen vacancies and strong synergistic effect between the multivalent Ce and Mn, the sensor exhibited excellent catalytic activity and selectivity for the electrochemical detection of H2O2 with a low quantitation limit of 2 nM. Moreover, Mn3O4/CeO2/GCE exhibited excellent reproducibility, repeatability, and long-term storage stability. Because of these remarkable analytical advantages, the constructed sensor was able to determine H2O2 released from living cells with satisfactory results. The results showed that the Mn3O4/CeO2 sensor is a promising candidate for a nanoenzymatic H2O2 sensor with the possibility of applications in physiology and diagnosis.