Increase In Electron Density Research Articles

PCTS‐Controlled Synthesis of L10/L12‐Typed Pt‐Mn Intermetallics for Electrocatalytic Oxygen Reduction

AbstractPt‐based intermetallics are recognized as effective catalysts for oxygen reduction reaction (ORR) in fuel cells. However, the synthesis of intermetallics often requires prolonged annealing and the effect of different crystal structures on ORR still need to be investigated. Herein, L12‐Pt3Mn and L10‐PtMn intermetallics with Pt‐skin are rapidly synthesized through an emerging periodic carbothermal shock method to investigate their ORR‐activity difference. The formation of L12‐Pt3Mn and L10‐PtMn can be well‐controlled by the Pt/Mn feeding ratio, pulse cycles, and temperature. Electrocatalytic investigations show that L12‐Pt3Mn presents a more positive half‐wave potential (0.91 V vs RHE) and onset potential (1.02 V vs RHE) than those of L10‐PtMn. The mass activity and specific activity of L12‐Pt3Mn are respectively fourfold and threefold greater than those of L10‐PtMn. Theoretical calculations indicate that the L12‐Pt3Mn has a more substantial work function than L10‐PtMn, thereby conferring L12‐Pt3Mn with an increased electron density allocation for catalytic involvement. This electron confinement imparts L12‐Pt3Mn with a Pt d‐band center lower than that of L10‐PtMn, consequently attenuating the adsorption of strongly bonded *O intermediates during the rate‐determining step. This study not only employs a straightforward method for intermetallic preparation but also elucidates the discrepancies in ORR activity across intermetallics with distinct structures.

Understanding ion and atom fluxes during high-power impulse magnetron sputtering deposition of NbCx films from a compound target

A combination of time-averaged mass spectroscopy (MS), time-averaged optical emission spectroscopy (OES), and plasma transport modeling was employed to understand the transport processes of ions and atoms in high-power impulse magnetron sputtering discharges resulting in changes in the stoichiometry of NbCx films during their deposition from a stoichiometric NbC compound target at different repetition frequencies and duty cycles. Mass spectrometry showed that the fluxes of ions originating from the elements of the target increase with increasing pulse power density (and decreasing pulse length) due to an increasing electron density and, thus, electron-impact ionization probability. Due to the higher ionization energy and much lower ionization cross section of C (compared to Nb), it was found that the contribution of C+ ions to the deposition flux is practically negligible. Additionally, OES tracked the densities of ions and atoms at different distances from the target. The OES analysis revealed that the atom densities decreased as the pulse power density increased. In contrast, the ion densities exhibited an increase, which is consistent with the findings of MS. Using the data from MS, OES, and modeling, we were able to estimate the fluxes of atoms to the substrate. Our observations demonstrated a transition from C-rich toward Nb-rich flux of film-forming species with increasing pulse power density, corresponding to changes in the film composition. We further discuss the role of internal plasma processes that are responsible for this transition.

Accelerating σ-Bond Metathesis at Sn(II) Centers.

Molecular main-group hydride catalysts are attractive as cheap and Earth-abundant alternatives to transition-metal analogues. In the case of the latter, specific steric and electronic tuning of the metal center through ligand choice has enabled the iterative and rational development of superior catalysts. Analogously, a deeper understanding of electronic structure-activity relationships for molecular main-group hydrides should facilitate the development of superior main-group hydride catalysts. Herein, we report a modular Sn-Ni bimetallic system in which we systematically vary the ancillary ligand on Ni, which, in turn, tunes the Sn center. This tuning is probed using Sn L1 XAS as a measure of electron density at the Sn center. We demonstrate that increased electron density at Sn centers accelerates the rate of σ-bond metathesis, and we employ this understanding to develop a highly active Sn-based catalyst for the hydroboration of CO2 using pinacolborane. Additionally, we demonstrate that engineering London dispersion interactions within the secondary coordination sphere of Sn allows for further rate acceleration. These results show that the electronics of main-group catalysts can be controlled without the competing effects of geometry perturbations and that this manifests in substantial reactivity differences.

Nitrogen modification enhances conductivity and reactivity of sulfidated zero-valent iron: Mechanism and Cr(VI) removal

The incorporation of electronegative elemental nitrogen into zero-valent iron (ZVI)/sulfidated zero-valent iron (S-ZVI) has emerged as an outstanding and promising way to improve decontamination performance. However, the impact of nitrogen modification on the electrical structure of ZVI/S-ZVI remains unclear. Herein, nitrogen-modified sulfidated zero-valent iron (S-N-ZVI) was successfully obtained utilizing cheap and accessible ammonium chloride as the nitrogen source. Raman spectra, FTIR, and density functional theory (DFT) calculations demonstrated that NH3 acts as the dominant nitrogen species. According to the projected density of states and charge-density difference calculations, N is successfully bound to Fe, resulting in a redistribution of surface charge and an increase in electron density of S-N-ZVI, which is reflected in the improved conductivity of S-N-ZVI. Compared with S-ZVI, S-N-ZVI demonstrates better performance in terms of Cr(VI) removal kinetics (kobs improved by 2.075 folds), resistance to air aging, reusability and ability to preserve FeSX stability. This study highlights that the electronic structure significantly impacts the physicochemical properties of S-ZVI and reveals the mechanism of nitrogen modification on the electronic structure of S-ZVI.

Amorphization-induced abundant coordinatively unsaturated Ni active sites in NiCo(OH)2 for boosting catalytic OER and HER activities at high current densities for water-electrolysis

The large overpotential required for oxygen evolution reaction (OER) is one of the major factors limiting the efficiency of electrochemical water-electrolysis for hydrogen production. In this work, to decrease OER energy barrier and obtain low overpotential, amorphous-crystalline NiCo(OH)2 nanoplates are in-situ grown on nickel foam surface to form a catalyst-based electrode (ac-NiCo(OH)2/NF) for water-electrolysis application. As the inner amorphization of NiCo(OH)2 results in increased electron density of the metal sites, leading to the formation of tensile Ni-O bond, the coordinatively unsaturated Ni sites in the down-shift d-band centers toward Fermi level can lower the antibonding states. This can lead to optimized adsorption and desorption energies for oxygen-containing intermediates for OER. As expected, the prepared ac-NiCo(OH)2/NF electrode presents a low overpotential of 364 mV to deliver 1000 mA cm−2 toward OER with impressively high robust stability. When this electrocatalyst electrode serves as both the anode and cathode, the assembled anion exchange membrane (AEM) electrolyser only needs a cell voltage of 1.68 V to drive the overall water-electrolysis process at a current density of 10 mA cm−2.

Seasonal morphology and solar activity dependence analysis of mid-latitude post-midnight enhancement using Global Ionospheric Map

In the mid-latitude ionosphere, the anomalous enhancement during nighttime is defined by an increase in electron density of the F2 region and/or total electron content. Studying this phenomenon is important because it enriches our understanding of the complex physical processes responsible for ionosphere formation. Furthermore, long-term investigations can reveal patterns and trends in ionospheric behavior, enabling more accurate predictions and improvements in ionosphere models. In this paper, we have investigated the mid-latitude post-midnight enhancement (MPE) utilizing Global Ionosphere total electron content (TEC) Maps (GIMs) during Low Solar Activity (LSA) years 2009, 2020 and High Solar Activity (HSA) year 2014. The investigation is done in the Northern and Southern Hemispheres during post-midnight hours (0–6 LT) focusing on the occurrence and strength of the MPE according to its seasonal morphology, in addition to the MPE occurrence dependence on the Interplanetary Magnetic Field (IMF) and the influence of the F10.7 on the strength of MPE. The findings indicate that the MPE occurrence and strength are more frequent and stronger during the winter solstice and depend on season, longitude, latitude, and level of solar activity. The MPE occurrence rate and strength reduce when solar activity is higher. The MPE occurrence rate shows a correlation with the IMF's By and Bz components. The negative correlation between F10.7 and MPE strength emphasizes solar activity's impact on MPE.

Tuning Redistribution of CuOx Nanoparticles on TiO2 Support.

Nanoparticles exhibit unique catalytic performance, depending on their nanoscale size. However, controlling the particle size of the supported catalysts is still challenging. Here, we present a method for tunable redistribution of CuOx nanoparticles on rutile TiO2 support by physically adding pristine TiO2. The redistribution is driven by the work function difference (WFD) between the TiO2 support and the TiO2 additive, both of which exhibit distinct values, as determined through Kelvin probe force microscopy and electron binding energy analysis. Addition of TiO2 with lower work function (rutile) promotes electron transfer toward the CuOx/TiO2 composite, resulting in nanoparticle aggregation, while addition of TiO2 with higher work function (anatase) results in smaller CuOx on TiO2. The increase in particle size and electron density of CuOx, driven by the addition of rutile TiO2, promoted the complete conversion of nitrobenzene (100%) within 5 h. This is 2.7 times that of dispersed and degraded CuOx driven by mixing with anatase TiO2 (36.9%).

High-Index Faceted Cu2 O@CuO Mesocrystals Act as Efficient Catalyst for Si Hydrochlorination to Trichlorosilane.

Mesocrystals (MCs) with high-index facets may have superior catalytic properties to those with low-index facets and their nanocrystal counterparts. However, synthesizing such mesocrystal materials is still very challenging because of the metastability of MCs and energetic high-index crystal facets. This work reports a successful solvothermal method followed by calcination for synthesizing copper oxide-based MCs possessing a core-shell structure (denoted as Cu2 O@CuO HIMCs). Furthermore, these MCs are predominantly bounded by the high-index facets such as {311} or {312} with a high-density of stepped atoms. When used as catalysts in Si hydrochlorination to produce trichlorosilane (TCS, the primary feedstock of high-purity crystalline Si), Cu2 O@CuO HIMCs exhibit significantly enhanced Si conversion and TCS selectivity compared to those with flat surfaces and their nanostructured counterparts. Theoretical calculations reveal that both the core-shell structure and the high-index surface contribute to the increased electron density of Cu sites in Cu2 O@CuO HIMCs, promoting the adsorption and dissociation of HCl and stabilizing the dissociated Cl* intermediate. This work provides a simple method for synthesizing high-index faceted MCs and offers a feasible strategy to enhance the catalytic performance of MCs.

One-step synthesis of S-doped C-vacancy g-C3N4 with honeycomb porous nanosheets structure for efficient visible-light-driven hydrogen evolution

A defective construction method was applied to design the molecular framework from the source and use the intermolecular forces of the raw materials to connect the long chains. The S-doped honeycomb g-C3N4 nanosheets were prepared by selective volatilization at elevated temperatures using melamine-tricyanuric acid-thiourea supramolecular liquid as precursor and template. In addition to significantly increasing the high surface area, the S-doped honeycomb g-C3N4 nanosheets also modify the band gap structure and shape. The introduction of the C defect also increased the number of reaction sites, improved visible light responsiveness, broadened the photoresponse range, and accelerated the segregated transfer of photogenerated carriers. The experimental results showed that the hydrogen production efficiency of S-PDCN-3 (The best sample of S-doped C-vacancy g-C3N4) is 23.78 mmol‧g−1‧h−1, which was 21.8 times that of BCN, namely Bulk g-C3N4 (1.1 mmol‧g−1‧h−1). After adding the photosensitizer (Erythrosin B) to the photocatalytic reaction system, EB + S-PDCN-3 (the best sample of S-doped honeycomb g-C3N4 nanosheets with the sensitizer) precipitated hydrogen up to 63.8 mmol‧g−1‧h−1, which was 17.78 times greater than the hydrogen production of the EB + BCN sample (3.59 mmol‧g−1‧h−1). Furthermore, the sample was observed to experience a reduction in band gap energy, an increase in electron density near VB and a reduction of H* adsorption–desorption barrier, all of which are essential for the enhancement of the hydrogen evolution reaction. Successful preparation of S-doped honeycomb g-C3N4 nanosheets provides a simple and efficient method for developing efficient g-C3N4 photocatalysts—potential applications in the development process of hydrogen energy and pollutant degradation.

Response of the F2-peak electron density and height to plasma depletion bays in the equatorial nighttime ionosphere observed by FORMOSAT-7/COSMIC-2

FORMOSAT-7/COSMIC-2 (F7/C2) satellite cluster, launched in June 2019, performs radio occultation experiments observing the vertical electron density profiles in the low-latitude ionosphere. The F7/C2 F2-peak electron density (NmF2) and height (hmF2) are used to identify and examine the behavior of the plasma depletion bay (PDB) structures in the equatorial nighttime ionosphere. The NmF2 reveals three distinct PDBs within 60°W–15°E, 30−90°E, and 110−160°E during June solstice, while a single PDB appears within 150−60°W during December solstice. All the four PDBs’ features simultaneously appear during March and September equinoxes. Asymmetries in the hmF2 over the PDB regions suggests that the electron density increases (decreases) are related to the NmF2 ascending (descending) in the summer (winter) hemispheres. Agreements between F7/C2 observations and HWM93 results show that the asymmetry of vertical motions driven by the neutral wind is the main causal mechanism for the longitudinal variation of PDBs.

Synthesis and Electrochemical Investigation of Phosphine Substituted Diiron Phosphadithiolate Complexes

AbstractThis work reports on ligand exchange reactions between a [FeFe] hydrogenase model containing the higher homologue (PhosDT) and phosphines selected to cover a variety of electronic properties and possible coordination modes. Additionally, the amount of the phosphines and the reaction temperature were varied to study the formation of complexes with multiple phosphines or altered binding modes. Due to steric effects caused by the position of the bridgehead, the phosphines bind preferentially at the more accessible iron centre on the phosphinate averted side. While all ligand exchanges resulted in a ligand‐specific main product at room temperature, reflux conditions induced decomposition in case of PhosDT‐(κ2‐dppe) and PhosDT‐(κ2‐dppv) and a change in the binding mode for the dppm containing complex. Moreover, we highlight two novel iron complexes obtained as side products of the reactions with dppe and dppv, while in case of dppm an additional model with two bridging phosphine ligands was generated. Finally, the six novel phosphine substituted PhosDT models were electrochemically investigated, revealing a cathodic shift compared to the starting material due to the increased electron density at the iron atoms. Moreover, the models with monodentate ligands exhibit a different CV pattern for the FeIFeI/FeIFe0 process than complexes with bidentate phosphines.

A Different Perspective on Tuning the Photophysical and Photochemical Properties: The Influence of Constitutional Isomers in Group 6 Carbonyl Complexes with Pyridyl-Mesoionic Carbenes.

Exploring novel and existing design principles to tune the photochemical and photophysical properties of transition-metal complexes is an important goal in contemporary research. Here, we highlight the influence of constitutional isomers of pyridyl-1,2,3-triazolylidene mesoionic carbene (MIC) ligands on the photophysical and photochemical properties of the corresponding tetracarbonyl group 6 metal complexes (M = Cr, Mo, W). All new complexes [M(C-C)] presented herein incorporate a C-C linked pyridyl-MIC ligand and were fully characterized by X-ray diffraction analysis, elemental analysis, and 1H NMR and IR spectroscopy. Detailed photophysical investigations reveal a single emission in the VIS region, which extends into the NIR with lifetimes of up to 3.5 μs in the solid state at lower temperatures. The quantum yields were determined for all three complexes, and, in particular, the W0 complex shows an unusually high quantum yield of 29% compared to the values of 0.02% obtained for the [M(C-N)] isomers investigated in earlier works. Beyond this, the investigated W0 complex also exhibits an emission at 717 nm in a fluid solution. The combination of luminescence and FTIR-step scan spectroscopy with theoretical calculations reveals an emissive 3MLCT state. Irradiation of the presented complexes leads to a clean cleavage of one axial CO ligand. A metastable 16 VE species with a vacant axial coordination site was detected in the solid state at low temperatures. In solution, the respective solvato complexes are formed. A dark reverse reaction is observed, as previously described for the [M(C-N)] analogues. The increased electron density induced by the C-C linked pyridyl-MIC ligand leads to an increased kinetic rate constant for the reformation of the starting species and is also reflected in the lower photodissociation quantum yields.

Mixed phase ZnSnN2 thin films for solar energy applications: Insight into optical and electrical properties

Zinc tin nitride (ZnSnN2, ZTN) films synthesized by magnetron co-sputtering at a temperature close to the ZTN decomposition point and with the cation ratio close to stoichiometric have been studied to gain insight into their structural, optical and electrical properties. According to X-ray diffraction and Raman spectroscopy, the samples are polycrystalline with some disorder in the cation sublattice. Hall effect measurements reveal n-type conductivity and very high carrier density above 1019 cm−3. At the lowest carrier density, the mobility achieves the best value ∼19 cm2/(V*s), which is acceptable for device applications. The optical band gap shows a blue shift with increasing electron density, which is related to the increase in tin content and the Burstein-Moss effect. Analysis of the blue shift in terms of the Burstein-Moss effect theory gives a value of 1.43 eV for the intrinsic band gap of ZTN in the mixed-phase state.

Influence of plasma inhomogeneity and ohmic heating on the nonlinear absorption of intense laser pulse in collisional magnetized plasma

AbstractThe nonlinear absorption in the interaction of an intense laser pulse with a collisional magnetized plasma is studied by considering the effects of plasma inhomogeneity, ohmic heating, and ponderomotive force. For this purpose, we obtain the plasma electron density, the effective dielectric permittivity, and the wave equation using the Maxwell and hydrodynamic equations and solve this equation by the Runge–Kutta numerical method. The results are shown that by increasing the plasma inhomogeneity, the inverse bremsstrahlung absorption coefficient is increased, and also the density ramp parameter and its sign can affect more the absorption coefficient than the temperature ramp parameter . However, when the initial electron density and temperature increase, the laser field amplitude and the absorption coefficient are increased and the spatial damping rate of the laser pulse becomes highly peaked inside the plasma. It is shown by increasing laser pulse energy, the nonlinear bremsstrahlung absorption coefficient is decreased significantly. The results also indicate that by increasing the external magnetic field, the dielectric permittivity is decreased while the laser energy spatial damping, and the absorption coefficient are increased. Moreover, it is found that by considering the ohmic heating effect, the electrons absorb further energy from the fields and consequently the nonlinear absorption is increased.

Efficient degradation of tetracycline in a photo-Fenton system constructed by combining MOF-derived Fe2O3/C/In2O3 heterojunction with vitamin C

The MOF-derived Fe2O3/C/In2O3 heterogeneous materials combined with vitamin C (AA) were first designed to construct a photo-Fenton system for the decomposition of tetracycline (TC). In this work, comparative analysis of TC degradation efficiency, photoluminescence (PL), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), and transient photocurrent (I-T) performance analysis revealed that the heterojunctions not only effectively promoted the response of visible light by the catalytic system, but also facilitated the separation of photogenerated electrons and holes to increase electron density, thus, the conversion efficiency of Fe3+/Fe2+ was effectively improved, and hydrogen peroxide was activated to generate ･OH. Besides, the conversion efficiency of Fe3+/Fe2+ has been further improved due to the addition of AA, which provides many active electrons for heterogeneous materials. The capture experiments revealed that the active substances (･OH, h+, and ･O-2) played a main role in the degradation of TC. The system degraded high concentrations of TC with the efficiency of 88.9 % within 60 min. The strategy provided a new method for improving the photo-Fenton advanced oxidation performance of Fe2O3.

Comment on Blagoveshchenskaya et al. Artificial Ducts Created via High-Power HF Radio Waves at EISCAT. Remote Sens. 2023, 15, 2300

The claim that incoherent scatter radar data show electron density enhancements of 50–80% during some ionospheric heating experiments in a recent paper is questioned. The backscatter from the monostatic radar can indeed be enhanced during these experiments, but the conclusion that a large electron density increase is the cause is almost certainly wrong. Some natural plasma line data are presented in support of our claim. Previously published studies of similar events and a possible explanation for the observed increases in backscattered power are pointed out.

Synergistic electronic structure tuning of self-assembled hollow hierarchical Ni-Fe-Co-P nanowire arrays on carbon cloth for enhanced water splitting

The pursuit of efficient and durable catalysts utilizing non-noble metals is critical for sustainable energy conversion through electrochemical water splitting. Herein, we present a novel bifunctional electrocatalyst of Ni-Fe-Co-P nanowire arrays on carbon cloth for overall water splitting, which was synthesized via a facile ion-exchange reaction between Co-MOF nanowires array and Fe2+/Ni2+ ions, followed by NaH2PO2-assisted phosphorization. By carefully controlling the molar ratios of Ni2+/Fe2+, the solid Co-MOF nanowire were transformed into hollow hierarchical nanowires assembled by nanosheets, allowing for effective modulation of the atomic composition of the titled catalyst. Specifically, this self-supported architecture showcases various advantageous features, including substantial surface areas, elevated structural void porosity, and accessible inner surfaces. These attributes not only facilitate the exposure of abundant active sites but also bolster the structural integrity, consequently facilitating efficient mass diffusion and charge transport. Density functional theory (DFT) calculations revealed that the synergistic effect of Ni, Fe, and Co elements with phosphorus vacancies leads to an increased electron density around the Fermi level, thus optimizing the adsorption free energy of H* and improving its intrinsic catalytic activity. As expected, the optimized catalyst exhibits low overpotentials of 106 and 249 mV for achieving a current density of 10 mA cm–2 in the hydrogen and oxygen evolution reactions, in 1.0 M KOH electrolyte, respectively. Moreover, the electrocatalyst exhibits outstanding bifunctional catalytic activity, achieving a current density of 10 mA cm−2 at a low voltage of 1.62 V in a two-electrode electrolyzer system. These findings demonstrate a potential avenue for the development of efficient and cost-effective bifunctional electrocatalysts for water splitting.

Evidence of charged interface states limited scattering in GaN heterostructures

This study provides experimental evidence of charged interface states limited scattering in III-nitride heterostructures. Temperature-dependent Hall measurements and temperature-dependent ID–VG measurements indicate a significant influence of the charged interface states on the electron mobility in different AlGaN/GaN heterostructures where the characteristic of the interface is controlled by modulating the growth conditions. Charged interface states at the AlGaN/GaN heterointerface lead to electron scattering as the distance between the centroid of the two-dimensional electron gas and the interface decreases with increasing electron density. It is observed that a component of experimental Hall mobility, which ranges between 9.2 × 103 and 3.4 × 104 cm2/V s among the three samples, obtained after adding all the scattering events using Matthiessen's rule cannot be explained completely by considering all the conventional scattering mechanisms such as phonon–phonon scattering, interface roughness scattering, and dislocation density scattering. An in-depth analysis reveals a significant scattering of channel electrons by the charged states at the GaN/AlN/AlGaN interface. Furthermore, the estimated interface states from the temperature-dependent subthreshold slopes conducted on the fabricated high electron mobility transistors are in good agreement with the charged interface states extracted from the temperature-dependent Hall measurements. A good understanding on this new scattering mechanism in the GaN heterostructure may help in designing high-performance III-nitride devices in the future.

Hot-Electron Dynamics Mediated Medical Diagnosis and Therapy.

Surface plasmon resonance excitation significantly enhances the absorption of light and increases the generation of "hot" electrons, i.e., conducting electrons that are raised from their steady states to excited states. These excited electrons rapidly decay and equilibrate via radiative and nonradiative damping over several hundred femtoseconds. During the hot-electron dynamics, from their generation to the ultimate nonradiative decay, the electromagnetic field enhancement, hot electron density increase, and local heating effect are sequentially induced. Over the past decade, these physical phenomena have attracted considerable attention in the biomedical field, e.g., the rapid and accurate identification of biomolecules, precise synthesis and release of drugs, and elimination of tumors. This review highlights the recent developments in the application of hot-electron dynamics in medical diagnosis and therapy, particularly fully integrated device techniques with good application prospects. In addition, we discuss the latest experimental and theoretical studies of underlying mechanisms. From a practical standpoint, the pioneering modeling analyses and quantitative measurements in the extreme near field are summarized to illustrate the quantification of hot-electron dynamics. Finally, the prospects and remaining challenges associated with biomedical engineering based on hot-electron dynamics are presented.

Unraveling the Origin of Donor‐Like Effect in Bismuth–Telluride‐Based Thermoelectric Materials

The donor‐like effect, depicting the uncontrollable increase of electron density that can significantly alter the thermoelectric performance of both p‐type and n‐type polycrystalline Bi2Te3‐based materials, has long been an intriguing phenomenon, while its origin is still elusive. Herein, it is found that different from the common argument, the donor‐like effect in Bi2Te3‐based polycrystals is a result of the oxygen‐adsorption‐induced evolution of the point defects. The dominant point defect in stoichiometric zone‐melted Bi2Te3 ingot is the acceptor‐like . During the fabrication of high‐strength polycrystals, the exposure of the powders to the air leads to their absorption of oxygen and the formation of secondary phase Bi2TeO5 in the following sintering process. This brings about a change of local chemical equilibrium and promotes the evolution of the intrinsic point defect from acceptor‐like to donor‐like . Notably, if the fabrication process is strictly controlled to minimize oxygen adsorption, the evolution of the point defects will be avoided, whereby the donor‐like effect disappears. Consequently, a reproducible high zT value of 1.0 at 325 K can be achieved in Bi2Te2.7Se0.3‐based polycrystals. These results highlight the importance of understanding the evolution of point defects, which is crucial for developing high‐performance Bi2Te3‐based polycrystals and corresponding fabrication processes.