Mn Substitution Research Articles

Hydrogen storage behaviour of Cr- and Mn-doped Mg2Ni alloys fabricated via high-energy ball milling

This paper describes the efficient preparation of an Mg2Ni alloy for hydrogen storage via high-energy ball milling mechanical alloying for 2 h. The degree of alloy amorphisation increases with increasing ball-milling time. Ball milling for 4 h affords partially amorphous alloys exhibiting the best hydrogen storage performance. Partial substitution of Ni with Cr and Mn improves the hydrogen absorption/desorption thermodynamics, kinetics and cycling performance of the alloy. Specifically, partial Mn substitution improves the cycling performance and reduces the activation energy of the hydrogen desorption reaction, effectively improving the hydrogen desorption kinetic performance. Mg2Ni0.8Mn0.2 shows the best cycling and hydrogen absorption/desorption kinetic performances. Partial Cr substitution reduces the entropy and enthalpy changes of the hydrogen absorption/desorption reaction and effectively reduces the temperature of the initial hydrogen absorption/desorption reaction. In particular, Mg2Ni0.9Cr0.1 shows the best thermodynamic performance.

Improved resistive switching performance and in-depth mechanism analysis in Mn-doped SrTiO3-based RRAM

Since memristors have shown great application prospects in non-volatile memory, neural synapse, brain-like chips, artificial intelligence (AI) and quantum computers, the research of memristors has received extensive attention. In this work, the resistive switching (RS) device with Ag/SrTiO3 (STO)/Ti structure was fabricated, and it can significantly improve the RS performance of device by doping Mn ions into STO to replace part of Ti ions. That is to say, the Ag/Mn-doped SrTiO3 (SMTO)/Ti device exhibits larger resistance window and better retention at room temperature. Finally, through in-depth mechanistic analysis, a physical model of the conducting filament and Schottky emission was established to understand the charge transport mechanism and RS behavior of the device. In particular, it provides favorable factors for the migration of ions and electrons through the Mn doping because the substitution of Mn for Ti ions reduces the volume of the STO crystal while distorting its crystal shape since the ionic radius of Mn is smaller than that of Ti. This work provides an important way to improve the RS properties of ABO3-type perovskite-based resistive random access memory (RRAM), and helps to explore the cutting-edge applications of high-performance RS devices in information processing and AI.

Theoretical Study of Intrinsic and Extrinsic Point Defects and Their Effects on Thermoelectric Properties of Cu2SnSe3.

Current understanding of the intrinsic point defects and potential extrinsic dopants in p-type Cu2SnSe3 is limited, which hinders further improvement of its thermoelectric performance. Here, we show that the dominant intrinsic defects in Cu2SnSe3 are CuSn and VCu under different chemical conditions, respectively. The presence of VCu will damage the hole conduction network and reduce hole mobility. Besides, we find that the substitution of Al, Ga, In, Cd, Zn, Fe, and Mn for Sn can inhibit the formation of VCu; introducing CuSn, FeSn, MnSn, and NiCu defects can significantly enhance electronic density of states near the Fermi level due to the contribution of 3d orbitals. Therefore, increasing the Cu content and/or introducing the above beneficial dopants appropriately are expected to cause enhancement of carrier mobility and/or thermopower of Cu2SnSe3. Furthermore, introducing AgCu, AlSn, ZnSn, GeSn, and MnSn defects can induce large mass and strain field fluctuations, lowering lattice thermal conductivity remarkably. Present results not only deepen one's insights into point defects in Cu2SnSe3 but also provide us with a guide to improve its thermoelectric properties.

Magnetic studies of Mn2+substituted Zn-ferrite nanoparticles: Role of secondary phases, bond angles and magnetocrystalline anisotropy

Magnetic studies of MnxZn1–xFe2O4 (x = 0.5, 0.6, 0.7) nanoferrite particles prepared by sol-gel auto combustion method are presented. The deviation of the oxygen positional parameter (U) from the ideal value of 0.375 is an indicator for the cation redistribution in the present ferrite systems. The variation of bond angles estimated from the cation distribution seemed to be strengthening of A–B superexhange interaction. The nature of M − H loops revealed that the present ferrite nanoparticles are in the single domain state showing superparamagnetism. The saturation magnetization (Ms) increases while coercivity (Hc) decreases with the substitution of Mn2+ ion concentration. The highest value of Ms = 25 emu/g was reported for the composition x = 0.7. It was observed that the blocking temperature (TB) is decreasing and again increasing with the doping level of Mn2+. From FC-ZFC curves, the uneven variation of magnetization (M) at 10 K can be found. It attributes to the cation distribution in the ferrite samples at 10 K is different from those of at 300 K. The Mӧssbauer spectra revealed that the ferrite nanoparticles exhibited both quadruple and hyperfine interactions can be found in the composition x = 0.7 while the ferrite nanoparticles exhibited that only quadruple interaction can be in the compositions x = 0.5 and 0.6. The isomer shift (δ) values showed the presence of high spin Fe3+ ions only. The paramagnetic doublets having higher value of quadruple splitting (Δ) are assigned to the core structure while doublets lower value of quadruple splitting (Δ) is assigned to shell structure. The present results are incorporated in terms of cation distribution, magnetocrystalline anisotropy considering the core-shell morphology of ferrite nanoparticles.

Effect of Mo addition on the microstructural evolution and mechanical properties of Fe–Ni–Cr–Mn–Al–Ti high entropy alloys

High-strength alloys are in urgent demand for engineering applications. Inducing multiple strengthening phases in a ductile matrix by microalloying is an effective alloy-strengthening strategy, especially the simultaneous formation of geometrically close-packed (GCP) phases and topologically close-packed (TCP) precipitation in high entropy alloys (HEAs). In this study, the microstructural evolution and mechanical properties of a series of (FeNi)67Cr15Mn10-xAl4Ti4Mox HEAs with x values of 1, 2, 3, 4, and 5 were analyzed in detail, with the substitution of Mn by Mo. This substitution does not change the L12 phase forming elements (Ni, Al and Ti) in the alloy, and enhance the σ phase precipitation, which meantime does not modify the oxidation resistance in thermal mechanical treatment. After aging at a temperature of 1023 K for 5 h, the matrix of the HEAs still maintains a face-cubic-centered structure. However, as Mn is replaced by Mo, hard σ precipitates are introduced into the matrix and the grains are significantly refined when x < 5. Therefore, the yield strength monotonically increases with increasing x. However, the formation of the hard σ precipitates also hinders the sustainability of the work hardening process, and thereby decreases the plasticity of the HEAs. Hence, the elongation at break monotonically decreases with increasing x. However, the high density of σ phase precipitates obtained at x = 5 prematurely terminates the work hardening process. Therefore, the highest ultimate tensile stress is obtained at x = 4, rather than x = 5. This also changes the fracture morphology from a coarse grain morphology for x < 5 to a typical brittle fracture at x = 5. Accordingly, (FeNi)67Cr15Mn6Al4Ti4Mo4 obtains the optimal mechanical properties overall.

The cationic interstitials induced resistive switching: a case study on Mn-doped SnO2

This work has explored the possible defects in Mn-doped SnO2 and compared the effects of interstitial Mn and oxygen vacancies on the electronic structure of SnO2. Combining the DFT calculations and experimental measurements, we found that when the Mn-doped SnO2 is synthesised under Sn-rich or O-poor conditions, the defect pair of Mn substitution and interstitial rather than oxygen vacancy will be formed, which induces energy band across the Fermi level and significantly affects the electronic structure of SnO2. With the Mn interstitials, stable intrinsic multi-level resistive states and optical SET can be achieved in the Mn-doped SnO2 memristors. This result can provide guidance in the fabrications of defective metal oxides and promote the investigations on cationic interstitial triggered multi-level resistive switching and optoelectronic memristors.

First principles calculation to investigate the effect of Mn substitution on Cu site in CeCu3-x Mn x V4O12 (x = 0, 1, 2 and 3) system.

Structural, electronic, elastic and magnetic properties of CeCu3-x Mn x V4O12 (x = 0, 1, 2 and 3) system have been carried out through DFT using GGA, GGA+U and HF potential. The investigation of structural optimization reveals that lattice parameters of the understudy system is reliable with the reported results and are increasing with the Mn substitution due to their greater atomic radii as compare to Cu atom. Both the cohesive energy and the enthalpy show that CeCu3V4O12 is the most thermodynamically stable among these compounds. When Mn is replaced by Cu in these compounds, not only it become semi-metals, but the host compound also changes from non-magnetic to anti-ferromagnetic and their electrical resistance provides further credence to their electronic behavior. Mechanical stability, anisotropy, and ductility are all demonstrated through the elastic characteristics of these compounds. Due to anti-ferromagnetic ductile nature of the Mn base compounds, it is expected that the compounds in the system may use for spintronic application and in magnetic cloaking devices.

Competitive crystallization, in situ separation and solidification mechanism of Cr-spinel crystal from Cr-bearing slag

The competitive crystallization, in situ separation, and solidification mechanism of Cr-spinel crystals were studied and the occupancy of Cr in the Cr-spinel lattice remained constant with the substitution of Fe and Mn.

Boosting catalytic activity of SrCoO2.52 perovskite by Mn atom implantation for advanced peroxymonosulfate activation.

Material-enhanced heterogeneous peroxymonosulfate (PMS) activation for degradation of antibiotic in water has attracted intensive attention. However, one challenge is the electron transfer efficiency from the material to PMS for reactive oxygen species (ROS) production. Considering that the B-sites of perovskite oxides are closely associated with the catalytic performance, partial substitution of the B-sites of perovskite oxides can enhance the redox cycle of metals. Consequently, adjusting the ratio of each element at the B site can introduce oxygen vacancies on the surface of perovskite. Herein, a method was developed in which manganese (Mn) partially substitutes B-sites to modify surface properties of SrCoO2.52 perovskite oxides, resulting in the enhancement of catalytic activity. In degradation kinetics studies using SrCoMnO3-δ-0.5/PMS (SrCoMnO3-δ-0.5 denotes that the molar substitution of Mn at the B site of SrCoO2.52 perovskite oxide is 0.5) reaction system and sulfamethoxazole (SMX) as the target pollutant, it was found that the reaction rate constant (kobs) is 0.287min-1 which is 2.4 times that of SrCoO2.52/PMS system. Experimental and theoretical analyses revealed that Mn-O covalent bonding governs the intrinsic catalytic activity of SrCoMnO3-δ-0.5 perovskite oxides. The Mn sites exhibits stronger adsorption energy with PMS than the Co sites, facilitating the breaking of O-O bond. Simultaneously, oxygen vacancies and surface adsorbed oxygen species have a synergistic effect for PMS adsorption. This work can provide a potential route in developing advanced catalysts based on manipulation of the B-sites of perovskite oxides for PMS activation.

The effect of quenching and Mn substitution for Ni on the magnetic properties of Mn25+xNi50-xGa25.

Ni-Mn based Heusler alloys have attracted widespread attention due to their novel physical properties. However, the structure of Mn2NiGa is metastable at room temperature, making it difficult to obtain its intrinsic physical properties and limiting its application. In this study, we obtained Mn2NiGa by replacing Ni in the precursor alloy Ni2MnGa with Mn and studied its magnetic properties, structures, and phase transitions with floating composition. In addition, we focused on the compositional segregation characteristics of Mn2NiGa caused by different heat treatment and quenching conditions. It was found that the samples quenched after annealing at 773 K for 48 hours exhibited abnormalities in magnetism, phase transformation, and structure. The further electron probe scanning characterization results reveal that the changes in these physical properties were related to component segregation caused by heat treatment.

Magneto-dielectric properties of B-site doped (Fe3+, Zr4+) BiMnO3 perovskite ceramic

A Zirconium (Zr4+) and Iron (Fe3+) doped perovskite compound i.e., BiMn1-x(TE)xO3 (x = 0.0, 0.1 and TE = Fe, Zr) were successfully prepared by mechanical alloying route. The X-ray diffraction pattern and HRTEM confirms the formation of single-phase perovskite in the proposed compositions. The lattice parameters were found to be reduced with Fe3+ and increased for Zr4+ ions entering in the crystal structure by substitution of Mn3+ ion. Scanning Electron micrographs (SEM) depicted the grain refinement of the oxidex. The XPS analysis exhibited the isovalent (Fe3+) and tetravalent (Zr4+) status of doping on the B-site Their effect on the oxygen vacancies, and the reduction of Mn3+ ions are reported. The dielectric study at 100 Hz and 400 °C(max.) indicate the decrement in dielectric constant to 12.76 × 103 in Fe+3 doped ceramic and 10.68 × 103 in the case of Zr+4 doped ceramic concerning that of 13.02 × 103 in pristine ceramic. M−H loop study exhibited ferromagnetic characteristics in doped and pristine ceramics. The Ms measured as 0.135emu, 0.114emu and 0.096emu in Fe doped, Zr doped and pristine ceramics respectively. The coexistence of magnetic and dielectricity exhibited the justified modifications of manganates perovskite ceramics and competently met the challenge of replacing conventional materials.

UV–vis-enhanced photothermal catalytic reforming of biomass model tar via LaMnxNi1-xO3 perovskite catalyst

Tar formation during biomass gasification reduces energy efficiency and poses a negative impact on downstream applications. A photothermal steam reforming (PTR) system based on LaMnxNi1-xO3 (0 ≤ x ≤ 1) perovskite was developed to convert tar into combustible gas. The effects of Mn substitution, temperature, and the steam to carbon ratio on PTR activity were investigated. Mn substitution increased the content of surface adsorbed oxygen and maintained the perovskite structure of LaMn0.4Ni0.6O3 (LM4N6). Moreover, LM4N6 showed improved optical absorption and electron-hole separation properties. LM4N6 presented 90 % carbon conversion during PTR at 400 °C. Due to the introduction of ultraviolet–visible light (UV–vis), LM4N6 obtained better catalytic activity and stability in PTR than in the thermal catalytic reforming process. Detailed characterization and experiments proved that UV–vis effectively activated Ni sites and the oxygen species on LM4N6 and formed a photothermal synergistic effect, which inhibited carbon deposition and improved catalytic activity and stability. This work provides a novel concept for the conversion and utilization of biomass tar at low temperatures.

Controllable preparation of nickel cobalt manganese ternary metal-organic frameworks for high-performance supercapacitor

In this study, Ni, Co and Mn metal-organic frameworks (MOFs, Ni2Co1-XMnX-MOFs-S, X = 0, 0.25, 0.5) nanorods are successfully obtained by a one-step hydrothermal method under the aid of C12H25SO4Na (SDS). The morphology and the size of the nanorods can be controlled by changing the doping method and content of Mn, resulting in the different electrochemical performances. The study proves that SDS has a great influence on the capacitance of the ternary metal NiCoMn-MOFs. Research results show that the optimized Ni2Co0.75Mn0.25-MOFs-S displays a capacitance of 1428 F·g−1 at current density of 1 A·g−1. Meanwhile, controlling partial substitution of Mn is beneficial to improve the stability of MOFs, such as the charge-discharge cycle stability of Ni2Co0.75Mn0.25-MOFs-S is high to 83.5 % after 3000 cycles. The energy density of the asymmetric supercapacitor (Ni2Co0.75Mn0.25-MOFs-S//AC) is 38.10 Wh·kg−1 at a power density of 884.38 W·kg−1. In addition, the act of Mn on improving material stability is studied.

Synthesis and thermoelectric properties of Cr-substituted higher manganese silicides prepared by pack cementation

Higher manganese silicides are attractive low-cost thermoelectric materials finding application in middle to high-temperature power generation. However, for practical use their performance needs to be enhanced. Pack cementation is a simple, green and economic method applied so far on the preparation of pure thermoelectric metal silicide powders. In this study, pack cementation is employed for the synthesis of doped thermoelectric powder for the first time as a promising single-step process. Compounds Mn1-xCrxSi1.80 (0.02≤x ≤ 0.15) at which Cr substitutes Mn site in the matrix are prepared and examined regarding their composition, microstructure and performance. Considerable amounts of CrSi2 impurity are present for x ≥ 0.07. The highest thermoelectric efficiency is achieved for Cr 4% substitution of Mn leading to the peak figure of merit ZTmax=0.59 at 814 K (∼35% enhancement). The measured oxidation resistance in this temperature region is high. Pack cementation has been successfully utilized to synthesize high-performance Cr-substituted higher manganese silicide powder.

First-principles calculations of Mn incorporation into GaAs(110)

Mn substitution reaction on the GaAs(110), observed in experiments, has been verified by first-principles pseudopotential calculation based on the spin density functional theory. Adsorption energy, substitution energy, desorption energy, and migration energies have been evaluated, and energy changes in each process were investigated in detail. We have found that the adsorption and substitution processes proceed with decreasing the total energy. However, it is considered that the Ga released by the substitution reaction migrate on the surface because the desorption energy of Ga atom is large. Furthermore, it has been found that spin densities of adsorbed Ga on the GaAs(110) surface distribute in the direction parallel to the surface, and the most stable position of adsorption Ga is slightly away from Mn site due to the magnetic interaction with the topmost surface Mn.

A comparative study on the structural, optical, and magnetic behavior of transition metal (Co and Mn) ions substituted Cr2O3 nanoparticles

A comparative study on structural, optical, and magnetic properties of TMxCr2−xO3 (TM = Co and Mn) nanoparticles was synthesized using a simple co-precipitation method with subsequent heat treatment. The structural characterizations of as-prepared nanoparticles were performed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. XRD pattern revealed the formation of rhombohedral Cr2O3 phase with space group R3¯c. The FTIR spectra illustrated the shifting of absorption bands of Cr2O3 nanoparticles with Co and Mn substitution due to strain induced within the crystal lattice. X-ray photoelectron spectroscopy (XPS) confirmed the presence of a mixed oxidation state of Cr and oxygen defects in the prepared nanoparticles. Furthermore, XPS spectra also demonstrated the presence of Co and Mn having +2 oxidation state. The reduction in optical band gap of host material was observed with Co and Mn substitution. The magnetic properties of as-synthesized nanoparticles were recorded using a SQUID magnetometer and temperature-dependent magnetic measurements illustrated the decrease of Neel temperature with Co and Mn substitution. It was also demonstrated that magnetization increases below about ∼ 120 K due to spin canting and spin frustration for both TM ions substituted Cr2O3 nanoparticles and is fitted using the 3D spin-wave model with Curie-Weiss law. The magnetic studies revealed the mixed paramagnetic (PM) and antiferromagnetic (AFM) order at room temperature and AFM mix with ferromagnetic (FM) order at low temperature explained using the bound magnetic polarons (BMP) model.

Ferromagnetic and antiferromagnetic orders in low dimensional PbBiFe1-xMxO4 (M = Mn and Co) solid solutions

A new solid solution of composition PbBiFe1-xMxO4 (M ​= ​Mn and Co, 0 ​≤ ​x ​≤ ​0.15–0.2) with low structural dimensions has been synthesized by solid-state reaction at 873–923 ​K. The crystal structures have been investigated using X-ray and neutron diffraction. The presence of Co2+/Co3+ on the Fe3+ sites and oxygen vacancies in PbBiFe1-xCoxO4 is revealed by its unusual volume increase and TGA, while the volume contraction of PbBiFe1-xMnxO4 indicates the substitution of Mn4+/Mn3+ on the Fe3+ sites. This leads to unexpected greater and smaller metal-metal distances inside the chains for the Co and Mn case, respectively, compared with the undoped materials. All the PbBiFe1-xMxO4 materials display long-range antiferromagnetic order but are suppressed by cationic substitution, as evidenced by a decrease in TN. Additional intrinsic short-range ferro- (or ferri-) magnetic transitions in the Co-doped materials are evidenced by magnetic hysteresis and frequency-dependent χ’ peak around TF. The introduction of ferromagnetic intrachain clusters in PbBiFe1-xCoxO4 is rationalized through a competitive mechanism between direct AFM exchange interaction and 90°- type FM superexchange interactions, which provided insights to tune the magnetic properties and design low dimensional functional materials.

High-rate performance and suppressed voltage decay of Li and Mn-rich oxide cathode materials upon substitution of Mn with Co for Li-ion batteries

In the current study, we found that the substitution of Mn in Li and Mn-rich oxides with Co results in the improved electrochemical performance in Li-ion batteries. The Co-containing Li and Mn-rich oxide, Li 1.2 Ni 0.2 Mn 0.48 Co 0.12 O 2 exhibit a specific capacity of about 205 mAh g -1 at C/5 rate with 83% capacity retention after 140 cycles along with a higher rate capability and also maintained a higher average discharge voltage upon cycling than that of Li 1.2 Ni 0.2 Mn 0.6 O 2 . • Influence of Co on the performance of Li and Mn-rich oxides has been tested. • Li 1.2 Ni 0.20 Mn 0.48 Co 0.12 O 2 exhibits a high specific capacity of 224 mAh g -1. • Interestingly, Li 1.2 Ni 0.2 Mn 0.48 Co 0.12 O 2 exhibits a specific capacity of 113 mAh g -1 at 4C rate, which is higher than Li 1.2 Ni 0.2 Mn 0.6 O 2 (70 mAh g -1 ) • EIS study indicates the low charge transfer resistance at high voltages for Li 1.2 Ni 0.2 Mn 0.48 Co 0.12 O 2. Layered Lithium and Mn-rich oxides, xLi 2 MnO 3 ·(1–x) LiMO 2 (M=Ni, Mn, Co) such as Li 1.2 Ni 0.2 Mn 0.6 O 2 (without Co) and Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 (upon substitution of both Mn and Ni with Co) are reported with high specific capacity. However, there is no report yet on the performance of Lithium and Mn-rich oxides when only Mn in these oxide cathodes is partially substituted with Co. In the current study, Lithium and Mn-rich cathodes such as Li 1.2 Ni 0.2 Mn 0.6 O 2 (LNMO) and Li 1.2 Ni 0.20 Mn 0.48 Co 0.12 O 2 (LNMCO) are synthesized by a sol-gel method followed by sintering at 900 o C for 12 h and their electrochemical performance has been evaluated at C/10 rate for 2 cycles (2.0 - 4.7 V) followed by 2.0-4.6 V at C/5 rate for 140 cycles. LNMO and LNMCO exhibit initial discharge capacities of around 210 and 224 mAh g -1 , respectively at the C/10 rate, with capacities retentions of 80.9 and 82.4 % after 140 cycles upon cycling at the C/5 rate. However, with an increase in the rate, Li 1.2 Ni 0.2 Mn 0.6 O 2 has a specific capacity around 70 mAh g -1 at 4C current rate, whereas Li 1.2 Ni 0.20 Mn 0.48 Co 0.12 O 2 exhibits 113mAh g -1 at the same current rate. This result clearly demonstrates that Li 1.2 Ni 0.20 Mn 0.48 Co 0.12 O 2 has a better rate capability than Li 1.2 Ni 0.2 Mn 0.6 O 2 material. During cycling, an excessive average discharge voltage is also maintained for Li 1.2 Ni 0.20 Mn 0.48 Co 0.12 O 2 .

Regulation of low-spin Fe of Mn-iron hexacyanoferrate for boosted potassium ion storage performance

K2Fe[Fe(CN)6] (KFHCF) is promising cathode material for potassium-ion batteries (PIBs). However, it suffers from limited capacity, poor cycling, and rate capability during cycling. Here, the low-spin Fe species coordinated with carbon atoms from cyanogen ligands (FeLS-C) are regulated and activated by manganese (Mn) substitution. The regulation is systematically investigated through theoretical simulation and experiments. The original electron configuration (t2g6eg0) of FeLS-C is changed with appropriate Mn-substitution (t2g3eg2), which improves the utilization of FeLS-C, accelerates the redox charge transfer and enhances the electrical conductivity of the material. The resultant K2Mn0.1Fe0.9[Fe(CN)6] (KMFHCF-0.1) delivers an improved reversible capacity of 135 mAh·g−1 at 100 mA g−1 while the capacity of pure KFHCF is only 118 mAh·g−1. It also demonstrates excellent rate performance (76 mAh·g−1 at 800 mA·g−1) and long cycling stability (0.3% capacity degradation per cycle over 200 cycles). Ex-situ measurements verify that the cathode undergoes a highly reversible solid solution process during K-ions insertion/extraction. The full cells with hard carbon anodes demonstrate a high reversible capacity of 110 mAh·g−1 and considerable energy density of 275 Wh·kg−1 as well as excellent cyclability and favorable rate performance. This work expands the design pathways for Prussian blue analogs cathode materials.

New insight of Mn(III) in δ-MnO2 for peroxymonosulfate activation reaction: Via direct electron transfer or via free radical reactions

Due to the increasing of industrial plastic waste and its refractory characteristics, it is extremely urgent to develop new degradation technology and environmentally friendly catalyst for industrial plastic waste. Manganese oxides are one of the most promising candidates for the catalytic degradation of plastic wastes. However, an improved understanding of the structural properties affecting their catalytic activity is required for high-efficient wastewater treatment. We herein report the surface reactivity effects of δ-MnO2 structural defects with regards to Bisphenol A (BPA) degradation/probe in the presence of peroxymonosulfate (PMS). Four δ-MnOx samples with different Mn(III) contents (different Mn(III)-deficient sample) were prepared and their structural properties as well as surface reactivity were characterized by batch test, ESR and XAFS analysis. For the Mn(III)-deficient sample, BPA removal was principally affected by direct electron transfer, with the adsorbed BPA degraded following hydroxylation. In contrast, a small fraction of Mn(III) substitution in δ-MnO2 could significantly encouraged the activation of PMS to produce SO4−☐and ☐OH, and a BPA degradation via beta scission. Moreover, the Mn(III)-rich δ-MnO2 demonstrate a high BPA removal rate even with a low sample load, which performed well following a reuse of five times. Our results provide a new way for the improvement of δ-MnO2 activity for the use of industrial plastic wastes treatment.