Tailoring Auger Recombination Dynamics in CsPbI3 Perovskite Nanocrystals via Transition Metal Doping.

Auger recombination is a pivotal process for semiconductor nanocrystals (NCs), significantly affecting charge carrier generation and collection in optoelectronic devices. This process depends mainly on the NCs' electronic structures. In our study, we investigated Auger recombination dynamics in manganese (Mn2+)-doped CsPbI3 NCs using transient absorption (TA) spectroscopy combined with theoretical and experimental structural characterization. Our results show that Mn2+ doping accelerates Auger recombination, reducing the biexciton lifetime from 146 to 74 ps with increasing Mn doping concentration up to 10%. This accelerated Auger recombination in Mn-doped NCs is attributed to increased band edge wave function overlap of excitons and a larger density of final states of Auger recombination due to Mn orbital involvement. Moreover, Mn doping reduces the dielectric screening of the excitons, which also contributes to the accelerated Auger recombination. Our study demonstrates the potential of element doping to regulate Auger recombination rates by modifying the materials' electronic structure.

Rationally Construction of Mn-Doped RuO2 Nanofibers for High-Activity and Stable Alkaline Ampere-Level Current Density Overall Water Splitting.

Nowadays, highly active and stable alkaline bifunctional electrocatalysts toward water electrolysis that can work at high current density (≥1000 mA cm-2) are urgently needed. Herein, Mn-doped RuO2 (MnxRu1-xO2) nanofibers (NFs) are constructed to achieve this object, presenting wonderful hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances with the overpotentials of only 269 and 461 mV at 1 A cm-2 in 1 m KOH solution, and remarkably stability under industrial demand with 1 A cm-2, significantly better than the benchmark Pt/C and commercial RuO2 electrocatalysts, respectively. More importantly, the assembled Mn0.05Ru0.95O2 NFs||Mn0.05Ru0.95O2 NFs electrolyzer toward overall water splitting reaches the current density of 10 mA cm-2 with a cell voltage of 1.52 V and also delivers an outstanding stability over 150 h of continuous operation, far surpassing commercial Pt/C||commercial RuO2, RuO2 NFs||RuO2 NFs and most previously reported exceptional electrolyzers. Theoretical calculations indicate that Mn-doping into RuO2 can significantly optimize the electronic structure and weaken the strength of O─H bond to achieve the near-zero hydrogen adsorption free energy (ΔGH*) value for HER, and can also effectively weaken the adsorption strength of intermediate O* at the relevant sites, achieving the higher OER catalytic activity, since the overlapping center of p-d orbitals is closer to the Fermi level.

Constructing Multi-Electron Reactions by Doping Mn2+ to Increase Capacity and Stability in K3.2V2.8Mn0.2(PO4)4/C of Phosphate Cathodes for Potassium-Ion Batteries.

Vanadium-based phosphate cathode materials (e.g., K3V2(PO4)3) have attracted widespread concentration in cathode materials in potassium-ion batteries owing to their stable structure but suffer from low capacity and poor conductivity. In this work, an element doping strategy is applied to promote its electrochemical performance so that K3.2V2.8Mn0.2(PO4)4/C is prepared via a simple sol-gel method. The heterovalent Mn2+ is introduced to stimulated multiple electron reactions to improve conductivity and capacity, as well as interlayer spacing. Galvanostatic intermittent titration technique (GITT) and in situ X-ray diffraction results further confirm that Mn-doping in the original electrode can obtain superior electrode process kinetics and structural stability. The prepared K3.2V2.8Mn0.2(PO4)4/C exhibits a high-capacity retention of 80.8% after 1 500 cycles at 2 C and an impressive rate capability, with discharge capacities of 87.6 at 0.2 C and 45.4 mA h g-1 at 5 C, which is superior to the majority of reported vanadium-based phosphate cathode materials. When coupled K3.2V2.8Mn0.2(PO4)4/C cathode with commercial porous carbon (PC) anode as the full cell, a prominent energy density of 175 Wh kg-1 is achieved based on the total active mass. Overall, this study provides an effective strategy for meliorating the cycling stability and capacity of the polyanion cathodes for KIB.

Efficiently photocatalysis activation of peroxymonosulfate by bimetallic metal-organic frameworks Mn-MIL-53(Fe) for ibuprofen degradation: Synergistic efficiency, mechanism and degradation pathways.

In this study, a UV-driven photocatalytic activation of peroxymonosulfate (PMS) system was constructed using bimetallic metal-organic frameworks to degrade pharmaceuticals and personal care products (PPCPs). Mn-MIL-53(Fe) was successfully synthesised by adjusting the doping ratio of Mn using solvothermal method. The removal of ibuprofen (IBP) by UV/Mn-MIL-53(Fe)/PMS process was as high as 79.7% in 30 min with a Mn doping ratio of 1.0 (molar ratio of Mn to Fe), and the reaction rate constant was 26.9% higher than undoped. Mn-MIL-53(Fe) had been systematically characterized in terms of its physical structure, microscopic morphology, surface functional groups and photoelectric properties. The mechanism investigation revealed that the cycling of Mn and Fe accelerated the rate of electron transfer in the system, which significantly increased the activation efficacy of PMS to generate more hydroxyl and sulfate radicals for IBP degradation. A total of 13 transformation products were detected during the degradation of IBP by the UV/Mn-MIL-53(Fe)/PMS process. Theoretical calculations were used to predict the sites on the IBP molecule that were vulnerable to attack, and four possible degradation pathways were deduced. The excellent stability and efficient catalytic properties of Mn-MIL-53(Fe) provided a promising solution to the problem of water treatment contaminated with PPCPs.

Stabilizing Lattice Oxygen through Mn Doping in NiCo2O4-δ Spinel Electrocatalysts for Efficient and Durable Acid Oxygen Evolution.

Design the electrocatalysts without noble metal is still a challenge for oxygen evolution reaction (OER) in acid media. Herein, we reported the manganese (Mn) doping method to decrease the concentration of oxygen vacancy (VO) and form the Mn-O structure adjacent octahedral sites in spinel NiCo2O4-δ (NiMn1.5Co3O4-δ), which highly enhanced the activity and stability of spinel NiCo2O4-δ with a low overpotential (η) of 280 mV at j=10 mA cm-2 and long-term stability of 80 h in acid media. The isotopic labelling experiment based on differential electrochemical mass spectrometry (DEMS) clearly demonstrated the lattice oxygen in NiMn1.5Co3O4-δ is more stable due to strong Mn-O bond and shows synergetic adsorbate evolution mechanism (SAEM) for acid OER. Density functional theory (DFT) calculations reveal highly increased oxygen vacancy formation energy (EVO) of NiCo2O4-δ after Mn doping. More importantly, the highly hydrogen bonding between Mn-O and *OOH adsorbed on adjacent Co octahedral sites promote the formation of *OO from *OOH due to the greatly enhanced charge density of O in Mn substituted sites.

Introducing Mn into ZIF-8 nanozyme for enhancing its catalytic activities and adding specific recognizer for detection of organophosphorus pesticides.

In order to design and establish a highly efficient and selective nanozyme-based sensing platform for the UV-vis detection of organophosphorus pesticides (OPs), Mn was introduced into ZIF-8 nanozyme for enhancing its catalytic activities and adding specific recognizer. The Mn-doped ZIF-8 (Mn-ZIF-8) nanocomposites were synthesized with a very facile one-pot method by heating the mixture of ZnO, 2-methylimidazole (Hmin) and Mn(CH3COO)2·4H2O in a solvent-free system at 180 °C for 8 h. The Mn-ZIF-8 nanocomposite showed a higher peroxidase activity and an additional thiocholine (TCh)-degradable property compared to the pristine ZIF-8. OPs could inhibit acetylcholinesterase (AChE) to catalyze the hydrolysis of acetylthiocholine (ATCh) to produce TCh, thus blocking the degradation of Mn-ZIF-8 and protecting the catalysis of the oxidation of colorless 3,3',5,5'-tetramethylbenzydine (TMB) to blue oxidized TMB (ox-TMB). Accordingly, a detection method for OPs with high sensitivity and selectivity was designed and established on the basis of the Mn-ZIF-8 nanozyme with a linear range of 0.1-20 nM and a limit of detection (LOD) as low as 54 pM.

Doping Mn2+in hybrid Ruddlesden-Popper phase of layered double perovskite (BA)4AgBiBr8.

The layered hybrid double perovskites emerged as excellent semiconductor materials owing to their environment compatibility and stability. However, these materials are weakly luminescent, and their photoluminescence (PL) properties can be modulated via doping. While Mn2+doping in perovskites is well known, but to the best of our knowledge the doping of Mn2+in layered double perovskites (LDPs) is yet to be explored. Herein, for the first time, we demonstrate the doping of Mn2+in hybrid inorganic-organic two-dimensional (2D) LDPs, (BA)4AgBiBr8(BA = n-butyl amine) via a simple solid-state mechanochemical route. The powder x-ray diffraction pattern, and electron paramagnetic resonance analysis confirm the successful incorporation of Mn2+ions inside (BA)4AgBiBr8lattice. The Mn2+doped 2D LDP shows energy transfer from host excitons to d-electrons of Mn2+ions, which results in red-shifted broad Mn2+emission band centered at 625 nm, attributed to thespin-forbidden4T1to6A1internal transition. This work opens up new possibilities to dope metal ions in 2D LDPs to tune the optical as well as magnetic properties.

A sulfur defective Mn-doped Ni3S2-xnanosheet for enhanced overall water splitting.

Non-precious and stable electrocatalysts towards both oxygen and hydrogen evolution reaction (OER/HER) are essential for effective overall water splitting in alkaline solution. In this study, a sulfur defective and manganese-doped nickel sulfide nanosheet that uniformly grown on nickel foam substrate (Mn-Ni3S2-x@NF) is synthesized. In alkaline solution, the Mn-Ni3S2-x@NF showed a low overpotential of 76 and 110 mV for OER and HER at 10 mA cm-2, respectively, together exhibiting excellent stability for both OER and HER reaction. It was confirmed by the experimental results that sulfur defects and Mn-doping synergistically optimized the electronic structure of Mn-Ni3S2-xwith increased electrical conductivity and enhanced OER/HER activity. Moreover, amorphous nickel oxyhydroxide (NiOOH) was observed byin situRaman during the OER condition, suggesting NiOOH is the active phase for OER reaction. Furthermore, the electrolyzer assembled by Mn-Ni3S2-x@NF merely needs 1.46 V to reach 10 mA cm-2and shows good stability as well. This study provides a feasible way to prepare high-efficiency bifunctional catalysts for overall water splitting.

Mn-Doped AgZnInS/ZnS Nanocrystals (NCs): Effects of Zn Etching on the NC Optical Properties.

Mn-doped I(II)-III-VI NCs (e.g., Mn-doped AgZnInS/ZnS NCs) possessing low-energy excitation, high brightness and long fluorescence lifetimes have been desired for time-gated fluorescence biosensing/imaging. In this type of NCs, their optical properties are significantly affected by the microscopic interactions between Mn and Mn and between Mn and host NC, the compositions of NCs, and the defects in NCs. On the other hand, it is known that Zn etching to core I(II)-III-VI NCs in NC synthesis can significantly enhance the NC brightness because Zn can exchange surface atoms (e.g., Ag and In) in NCs to minimize NC surface-defects. But for Mn-doped I(II)-III-VI NCs, Zn etching could etch out not only surface-atoms of host NCs (e.g., Ag and In) but also Mn in NCs. As a result, it could significantly affect the NC compositions and the microscopic interactions between Mn and Mn as well as between Mn and host NC, and thus the optical properties of NCs (like lifetime and absorption/emission spectra). Therefore, it is needed to investigate how Zn etching would affect the optical properties of such Mn-doped NCs. In this study, a series of Mn-doped AgZnInS NCs with different Mn doping levels were prepared through nucleation doping, and then Zn etching was applied to etch these core NCs. To identify the effects of Zn etching on NC optical properties, ZnS coating (a different ZnS shelling approach by injecting Zn precursor and S precursor alternately in synthesis) was performed on the same Mn:AgZnInS NCs, and the optical properties of NCs with these two different ZnS shelling approaches were compared. Experimental results showed that under appropriate Mn doping levels in synthesis, Zn etching instead of ZnS coating can produce low-energy excitable NCs with higher QYs and longer lifetimes, which would further facilitate the use of such NCs in time-gated fluorescence measurement. To understand the reasons for the different optical properties under different ZnS shelling approaches, the material characteristics of the prepared NCs were further measured/analyzed and the possible fluorescence mechanisms were discussed.

Tailoring Electrochemical Performance of Co3O4 Electrode Materials by Mn Doping.

Reasonable design of electrode materials is the key to solving the low energy density of the supercapacitors. Transition metal oxide Co3O4 material is commonly used in the field of supercapacitors, but the poor cycle stability limits its practical application. Herein, we report 0.3Mn-Co3O4 nanostructures grown on nickel foam by a facile one-step hydrothermal approach. The morphology of the samples can be regulated by the introduction of different amounts of Mn ions. The specific capacitance reaches 525.5 C/g at 1 A/g. The performance of 0.3Mn-Co3O4 material is significantly improved due to its excellent stability and conductivity, which makes it a suitable electrode material for supercapacitors. A flexible asymmetric device is also fabricated using the sample as the cathode. The assembled capacitor still possesses a desirable cycle stability after charging and discharging of 10,000 times, and its capacitance retention rate can reach 83.71%.

Interfacial Manganese-Doping in CsPbBr3 Nanoplatelets by Employing a Molecular Shuttle.

Mn-doping in cesium lead halide perovskite nanoplatelets (NPls) is of particular importance where strong quantum confinement plays a significant role towards the exciton-dopant coupling. In this work, we report an immiscible bi-phasic strategy for post-synthetic Mn-doping of CsPbX3 (X=Br, Cl) NPls. A systematic study shows that electron-donating oleylamine acts as a shuttle ligand to transport MnX2 through the water-hexane interface and deliver it to the NPls. The halide anion also plays an essential role in maintaining an appropriate radius of Mn2+ and thus fulfilling the octahedral factor required for the formation of perovskite crystals. By varying the thickness of parent NPls, we can tune the dopant incorporation and, consequently, the exciton-to-dopant energy transfer process in doped NPls. Time-resolved optical measurements offer a detailed insight into the exciton-to-dopant energy transfer process. This new approach for post-synthetic cation doping paves a way towards exploring the cation exchange process in several other halide perovskites at the polar-nonpolar interface.

Exciton-to-Dopant Energy Transfer in Mn-Doped Cesium Lead Halide Perovskite Nanocrystals.

We report the one-pot synthesis of colloidal Mn-doped cesium lead halide (CsPbX3) perovskite nanocrystals and efficient intraparticle energy transfer between the exciton and dopant ions resulting in intense sensitized Mn luminescence. Mn-doped CsPbCl3 and CsPb(Cl/Br)3 nanocrystals maintained the same lattice structure and crystallinity as their undoped counterparts with nearly identical lattice parameters at ∼0.2% doping concentrations and no signature of phase separation. The strong sensitized luminescence from d-d transition of Mn2+ ions upon band-edge excitation of the CsPbX3 host is indicative of sufficiently strong exchange coupling between the charge carriers of the host and dopant d electrons mediating the energy transfer, essential for obtaining unique properties of magnetically doped quantum dots. Highly homogeneous spectral characteristics of Mn luminescence from an ensemble of Mn-doped CsPbX3 nanocrystals and well-defined electron paramagnetic resonance spectra of Mn2+ in host CsPbX3 nanocrystal lattices suggest relatively uniform doping sites, likely from substitutional doping at Pb2+. These observations indicate that CsPbX3 nanocrystals, possessing many superior optical and electronic characteristics, can be utilized as a new platform for magnetically doped quantum dots expanding the range of optical, electronic, and magnetic functionality.

Red-Tuned Mn d-d Emission in Doped Semiconductor Nanocrystals.

Light-emitting Mn-doped semiconductor nanocrystals have been extensively studied for the last three decades for their intense and stable Mn d-d emission. In principle, this emission should be fixed at 585 nm (yellow), but recent studies have shown that the emission can be widely tuned even to 650 nm (red). This is a spectacular achievement as this would make Mn-doped nanocrystals efficient and tunable light emitters. Keeping these developments in view, the chemistry of the synthesis of these materials, their photophysical processes and the expected origins of their red emission are summarized in this Minireview. All the related important studies from 1992 onwards are chronologically discussed, and one particular case is elaborated on in detail. As these materials are potentially important for biology, and photovoltaic, sensing and light-emitting devices, this Minireview is expected to help researchers investigating the chemistry, physics and applications of these materials.

Chemodynamic PtMn Nanocubes for Effective Photothermal ROS Storm a Key Anti-Tumor Therapy in-vivo.

Background: Chemodynamic therapy (CDT) is a new treatment approach that is triggered by endogenous stimuli in specific intracellular conditions for generating hydroxyl radicals. However, the efficiency of CDT is severely limited by Fenton reaction agents and harsh reaction conditions. Methods: Bimetallic PtMn nanocubes were rationally designed and simply synthesized through a one-step high-temperature pyrolysis process by controlling both the nucleation process and the subsequent crystal growth stage. The polyethylene glycol was modified to enhance biocompatibility. Results: Benefiting from the alloying of Pt nanocubes with Mn doping, the structure of the electron cloud has changed, resulting in different degrees of the shift in electron binding energy, resulting in the increasing of Fenton reaction activity. The PtMn nanocubes could catalyze endogenous hydrogen peroxide to toxic hydroxyl radicals in mild acid. Meanwhile, the intrinsic glutathione (GSH) depletion activity of PtMn nanocubes consumed GSH with the assistance of Mn3+/Mn2+. Upon 808 nm laser irradiation, mild temperature due to the surface plasmon resonance effect of Pt metal can also enhance the Fenton reaction. Conclusion: PtMn nanocubes can not only destroy the antioxidant system via efficient reactive oxygen species generation and continuous GSH consumption but also propose the photothermal effect of noble metal for enhanced Fenton reaction activity.

Hybrid Surface Modification and Bulk Doping Enable Spent LiCoO2 Cathodes for High-Voltage Operation.

The emerging market demand for high-energy-density of energy storage devices is pushing the disposal of end-of-life LiCoO2 (LCO) to shift toward sustainable upgrading into structurally stable high-voltage cathode materials. Herein, an integrated bulk and surface commodification strategy is proposed to render spent LCO (S-LCO) to operate at high voltages, involving bulk Mn doping, near surface P gradient doping, and Li3PO4/CoP (LPO/CP) coating on the LCO surface to yield upcycled LCO (defined as MP-LCO@LPO/CP). Benefiting from hybrid surface coating with Li+-conductive Li3PO4 (LPO) and electron conductive CoP (CP) coupled with Mn and P co-doping, the optimized MP-LCO@LPO/CP cathode exhibits enhanced high-voltage performance, delivering an initial discharge capacity of 218.8 mAh g-1 at 0.2 C with excellent capacity retention of 80.9% (0.5 C) after 200 cycles at a cut-off voltage of 4.6 V, along with 96.3% of capacity retention over 100 cycles at 4.5 V. These findings may afford meaningful construction for the upcycling of commercial S-LCO into next-generation upmarket cathode materials through the elaborate surface and bulk modification design.

Facile Al2O3 coating suppress dissolution of Mn2+ in Mn-substituted Na3V2(PO4)3 with outstanding electrochemical performance for full sodium ion batteries.

Na3V2(PO4)3 (NVP) encounters significant obstacles, including limited intrinsic electronic and ionic conductivities, which hinder its potential for commercial feasibility. Currently, the substitution of V3+ with Mn2+ is proposed to introduce favorable carriers, enhancing the electronic conductivity of the NVP system while providing structural support and stabilizing the NASICON framework. This substitution also widens the Na+ migration pathways, accelerating ion transport. Furthermore, to bolster stability, Al2O3 coating is applied to suppress the dissolution of transition metal Mn in the electrolyte. Notably, the Al2O3 coating serves a triple role in reducing HClO4 concentration in the electrolyte, inhibiting Mn dissolution, and functioning as the ion-conducting phase. Likewise, carbon nanotubes (CNTs) effectively hinder the agglomeration of active particles during high-temperature sintering, thereby optimizing the conductivity of NVP system. In addition, the excellent structural stability is investigated by in situ XRD measurement, effectively improving the volume collapse during Na+ de-embedding. Moreover, the Na3V5.92/3Mn0.04(PO4)3/C@CNTs@1wt.%Al2O3 (NVMP@CNTs@1wt.%Al2O3) possesses unique porous structure, promoting rapid Na+ transport and increasing the interface area between the electrolyte and the cathode material. Comprehensively, the NVMP@CNTs@1wt.%Al2O3 sample demonstrates a remarkable reversible specific capacity of 122.6 mAh/g at 0.1 C. Moreover, it maintains a capacity of 115.9 mAh/g at 1 C with a capacity retention of 90.2 mAh/g after 1000 cycles. Even at 30 C, it achieves a capacity of 87.9 mAh/g, with a capacity retention rate of 84.87 % after 6000 cycles. Moreover, the NVMP@CNTs@1wt.%Al2O3//CHC full cell can deliver a high reversible capacity of 205.5 mAh/g at 0.1 C, further indicating the superior application potential in commercial utilization.

Mono- and Co-Doped Mn-Doped CsPbCl3 Perovskites with Enhanced Doping Efficiency and Photoluminescent Performance.

To investigate the effect of Mn and other metal dopants on the photoelectronic performance of CsPbCl3 perovskites, we conducted a series of theoretical analyses. Our findings showed that after Mn mono-doping, the CsPbCl3 lattice contracted and the bonding strength increased, resulting in a more compact structure of the metal octahedral cage. The relaxation of the metal octahedral cage, along with the Jahn-Teller effect, results in a decrease in lattice strain between the octahedra and a reduction in the energy of the entire lattice due to the deformation of the metal octahedron. These three factors work together to reduce intrinsic defects and enhance the stability and electronic properties of CsPbCl3 perovskites. The solubility of the Mn dopant is significantly increased when co-doped with Ni, Fe, and Co dopants, as it compensates for the lattice strain induced by Mn. Doping CsPbCl3 perovskites reduces the band gap due to the decreased contributions of 3d orbitals from the dopants. Our analyses have revealed that strengthening the CsPbCl3 lattice and reducing intrinsic defects can result in improved stability and PL properties. Moreover, increasing Mn solubility and decreasing the bandgap can enhance the PLQY of orange luminescence in CsPbCl3 perovskites. These findings offer valuable insights for the development of effective strategies to enhance the photoelectronic properties of these materials.

Electrochemically activated 3D Mn doped NiCo hydroxide electrode materials toward high-performance supercapacitors.

Metal doping and electrochemical reconstruction had been demonstrated to play a significant role in the preparation of advanced electrode materials, which is helpful to achieve high-performance supercapacitors. However, there was no report about the combination of two technologies to construct electrode materials and their applications in supercapacitors. Herein, a rational Mn doped NiCo sulfide compound with open structure composed of 2D ultra-thin nanosheets was designed via a Mn doping route. In order to further improve the energy storage performance of the resulted product, we adopted a simple electrochemical activation strategy to reconstruct it. It was found that the reconstructed sample not only exhibited an irreversible evolution of structure (from 2D sheet to 3D channel), but also the phase transformation (from metal sulfide to metal hydroxide). Benefiting from the stable 3D curved structure with numerous channels, multitudinous charge transfer provided by numerous valence states of metals and copious active sites by low crystalline state, the in-situ self-reconstructed sample exhibited superior capacitance. In details, the optimized product delivered excellent specific capacitance of 1462C g-1 (3655F/g) at 1 A g-1 and high rate capability of 66 % even at 5 A g-1. Moreover, the corresponding assembled asymmetric supercapacitor exhibited an excellent energy density of 141.8 Wh kg-1 at a power density of 850.1 W kg-1, and the capacitance retention rate was 96.6 % even after 5000 cycles, which was distinctly superior than thoseofthe previous similarmaterialsreported. In a word, this work provided a feasible and effective strategy to construct 3D Mn doped NiCo hydroxide electrode materials toward high-performance supercapacitors.

Study on Enhancing the Thermoelectric Stability of the ß-Cu2Se Phase by Mn Doping.

Cu2Se is a promising thermoelectric (TE) material due to its low cost, Earth abundance, and high thermoelectric properties. However, the biggest problem of Cu2Se is its unstable chemical properties. In particular, under the action of an electric field or gradient temperature field, the chemical potential of copper ions inside the material increases. When the external field is strong enough, the chemical potential of copper ions at the negative end of the material reaches the chemical potential of elemental copper. Under these conditions, copper ions must precipitate out, causing Cu2Se to be unstable, and making it unsuitable for use in applications. In this study, we prepared Cu2-xMnxSe (x = 0, 0.02, 0.04 and 0.06) series bulk materials by vacuum melting-annealing and sintered by spark plasma sintering (SPS). We investigated the effects of Mn doping on the composition, microstructure, band structure, scattering mechanism, thermoelectric properties, and stability of Cu2Se. The results show that Mn doping can adjust the carrier concentration, promote the stabilization of the ß-phase structure and improve the electrical properties of Cu2Se. When x = 0.06, the highest power factor (PF) value of Cu1.94Mn0.06Se at 873 K was 1.62 mW m-1 K-2. The results of carrier scattering mechanism analysis based on the conductivity ratio method show that the sample doped with Mn and pure Cu2Se had the characteristics of ionization impurity scattering, and the scattering factor was 3/2. However, the deterioration in thermal conductivity was large, and a superior zT value needs to be obtained. The cyclic test results of high-temperature thermoelectric properties show that Mn doping can hinder Cu+ migration and improve its thermoelectric stability, which preliminarily verifies the feasibility of using the stable zirconia mechanism to improve the thermoelectric stability of Cu2Se.

Mechanistic insight into the charge carrier separation and molecular oxygen activation of manganese doping BiOBr hollow microspheres.

High-efficiency separation of photogenerated charges and molecular oxygen activation is very important for photocatalytic removal of organic pollutants. However, the current understanding of the effect mechanism of metal substitution for the separation of photo-generated charges and molecular oxygen activation is still poor. Herein, efficient manganese (Mn)-doped BiOBr hollow microspheres synthesis, systematic characterizations, and theoretical calculation discovered that Mn-doping could not only induce produce oxygen vacancies (OVs), but also can act as active sites for catalytic reactions. The induced production of OVs and Mn2+/Mn3+ by Mn optimal doping introduced into BiOBr can synergistic promote the separation of photogenerated charges and molecular oxygen activation leads to significantly enhances degradation of crystal violet (CV). Upon analysis, Mn-doping introducing unsaturated d-orbital with bridging O2- formation π-donation accelerated the separation of photo-generated charges. Meanwhile, the larger overlap of Mn-3d orbitals with O2-2p orbitals forms a π-donation bond with charge transfer from metal to O2 leading to the oxygen-oxygen (OO) bond length and molecular oxygen activation. Finally, we proposed a possible mechanism to explain the highly efficient photocatalytic degradation performance of the acquired photocatalysts. This study provides not only a novel strategy for the rational design of highly active photocatalysts, but also in-depth insights into the separation of photo-generated charges and molecular oxygen activation.