Defect Formation Energies Research Articles

Structure and thermodynamics of defects in Na-feldspar from a neural network potential

The diffusive phase transformations occurring in feldspar, a common mineral in the crust of the Earth, are essential for reconstructing the thermal histories of magmatic and metamorphic rocks. Due to the long timescales over which these transformations proceed, the mechanism responsible for sodium diffusion and its possible anisotropy has remained a topic of debate. To elucidate this defect-controlled process, we have developed a neural network potential (NNP) trained on first-principle calculations of Na-feldspar (albite) and its charged defects. This force field reproduces various experimentally known properties of feldspar, including its lattice parameters and elastic constants as well as heat capacity and DFT-calculated defect formation energies. A new type of dumbbell interstitial defect is found to be most favorable, and its free energy of formation at finite temperature is calculated using thermodynamic integration. The necessity of including electrostatic corrections before training an NNP is demonstrated by predicting more consistent defect formation energies. Published by the American Physical Society 2024

Modulation of Photocatalytic CO2 Reduction by n-p Codoping Engineering of Single-Atom Catalysts.

Transition metal (TM) single-atom catalysts (SACs) have been widely applied in photocatalytic CO2 reduction. In this work, n-p codoping engineering is introduced to account for the modulation of photocatalytic CO2 reduction on a two-dimensional (2D) bismuth-oxyhalide-based cathode by using first-principles calculation. n-p codoping is established via the Coulomb interactions between the negatively charged TM SACs and the positively charged Cl vacancy (VCl) in the dopant-defect pairs. Based on the formation energy of charged defects, neutral dopant-defect pairs for the Fe, Co, and Ni SACs (PTM0) and the -1e charge state of the Cu SAC-based pair (PCu-1) are stable. The electrostatic attraction of the n-p codoping strengthens the stability and solubility of TM SACs by neutralizing the oppositely charged VCl defect and TM dopant. The n-p codoping stabilizes the electron accumulation around the TM SACs. Accumulated electrons modify the d-orbital alignment and shift the d-band center toward the Fermi level, enhancing the reducing capacity of TM SACs based on the d-band theory. Besides the electrostatic attraction of the n-p codoping, the PCu-1 also accumulates additional electrons surrounding Cu SACs and forms a half-occupied dx2-y2 state, which further upshifts the d-band center and improves photocatalytic CO2 reduction. The metastability of Cl multivacancies limits the concentration of the n-p pairs with Cl multivacancies (PTM@nCl (n > 1)). Positively charged centers around the PTM@nCl (n > 1) hinders the CO2 reduction by shielding the charge transfer to the CO2 molecule.

Microscopic damage in eutectic SnPb alloy: First-principles calculations and experiments

This study aims to comprehensively elucidate the microscopic origins of damage in eutectic SnPb alloy through atomic-scale investigations, a crucial endeavor for enhancing the alloy’s properties and furthering the development of Pb-free solders. First-principles calculations based on density functional theory (DFT) were employed to examine the mechanical constants and defect formation energies of the Pb phase, the β-Sn phase, and potential Sn/Pb eutectic phases in the SnPb alloy. The Voigt-Reuss-Hill approximation was utilized to derive the mechanical parameters of the elastically stable structure in SnPb alloy, facilitating the prediction of its mechanical properties. The defect formation energy calculations revealed a higher difficulty in forming vacancy defects in the β-Sn phase compared to the Pb phase. This discrepancy can be attributed to the stronger interactions between Sn atoms, resulting in the formation of more stable Sn-Sn bonds, thereby impeding vacancy generation in the β-Sn phase. Furthermore, the Pb phase exhibited a tendency for Sn atoms to occupy octahedral interstitial sites, whereas in the β-Sn phase, Pb atoms tended to displace neighboring Sn atoms along the [110] orientation into adjacent interstitial sites and occupy their lattice positions. Experimental observations complemented these calculation findings, demonstrating significant Sn element presence, up to 27.22 at%, in the Pb-rich phase, with notable microvoid damage primarily concentrated within this region. This observation aligns with the conclusions drawn from first-principles calculations and unveils the microscopic origins of damage in eutectic SnPb alloys.

Investigations on the photoelectric properties of the Mn doped inorganic CsSnCl3 perovskite

Mn dopant significantly improves the photoluminescent performance of CsSnCl3. To find the exact interactions induced by Mn dopant into the CsSnCl3 crystal, we studied the geometric, electronic and excitonic properties for these systems. We found an increased formation energy of the VSn defect, which promoting the stability and the luminescence properties of CsSnCl3 accordingly. Via analyses from the crystal field theory and the COHP calculations, we revealed that the transition of the 3d orbital of Mn2+ ion from 4T1→6A1 plays a crucial role in enhancing the luminescence of CsSnCl3. Also, we show that with the introduction of Mn dopant, the exciton binding energy increases, generating the more tight bounding interactions between the electron and hole pairs which results in the higher luminescence efficiency. Therefore, our results show that Mn doping indeed enhances the photoluminescence properties of CsSnCl3 and facilitates its application in the field of light-emitting devices.

Insight into the damage mechanism of KH2PO4 crystals with BaK-SiP by hybrid density functional theory

The laser-induced damage threshold (LIDT) of potassium dihydrogen phosphate (KDP) crystals is one of the key factors affecting the application of KDP crystals for Inertial confinement fusion (ICF). Previous studies have found that Ba, Si impurities can form BaK-SiP defect complexes in KDP crystals. However, the microscopic nature of the defect complexes is still unclear. We precisely calculate defect formation energy (DFE) in various charge states (-1, 0, +1), configuration coordinate diagram (CCD) and optical spectra by hybrid density functional theory. We found BaK-SiP introduce two defect states in the band gap. In the transitions (BaK-SiP)✕+h∙→(BaK-SiP)∙ and (BaK-SiP)✕+e-→(BaK-SiP)′, excited state and ground state have an intersection point in the Marcus inverted region and the activation energies are nearly 0 eV. The results showed that the defect complexes could capture holes and electrons through lattice relaxation, causing significant heat deposition and resulting in crystal damage. This implies a new damage mechanism of KDP crystals is discovered.

Thickness-derived optical-electrical management in Sn-based perovskite solar cells

Tin-based perovskite solar cells (TPSCs) have attracted great attention due to their promising photovoltaic performance and environmental friendliness. Adequate photon trapping and efficient carrier utilization are known to be the keys to achieving high-performance devices, which are closely related to the thickness of the light-absorbing layer and the quality of film formation, respectively. Due to the ultra-fast crystallization characteristics and low defect formation energy, thick tin-based perovskite films are faced with poor electrical performance due to poor quality. Thin tin-based perovskite films are easy to achieve low defects and high crystallization quality, but insufficient thickness leads to the problem of insufficient light trapping. To address these issues, we have thoroughly investigated the various aspects of the photoelectric conversion process in TPSC devices and, for the first time, explored the behavior of front-end optical field management. It is found that the self-constructed microcavity effect can effectively improve the light trapping efficiency under the premise that a thin light-absorbing layer is used, so that sufficient photon trapping and excellent carrier transport characteristics can be ensured simultaneously to realize a high-performance device. Different from the traditional film formation and defect modulation strategy, the present work provides a feasible idea for the performance enhancement of TPSC devices, and is also of great significance for cost control and environmental protection issues in commercial applications.

Assessment of uranium nitride interatomic potentials

Uranium mononitride (UN) is a promising nuclear fuel due to its high fissile density, high thermal conductivity, and suitability for reprocessing. In this study, two uranium nitride interatomic potentials are assessed: Tseplyaev and Starikov's angular-dependent potential and Kocevski et al.'s embedded atom model potential. Predictions of the thermophysical and elastic properties of UN, ▪, and α- and β-▪ computed using both potentials are assessed and compared to available experimental data. The Tseplyaev potential performs better with the energetic aspects of UN, e.g., specific heat capacity and point defect formation energies, whereas the Kocevski potential performs better with the structural aspects of UN, e.g., thermal expansion as well as with the elastic properties. The reasons why the Kocevski potential underestimates the UN specific heat are explained by examining the UN phonon properties modeled using both potentials. The Kocevski potential shows better identification of the mechanical stability ranges of UN, ▪, and α- and β-▪, reasonably predicting the melting point of UN and predicting stable structures for ▪ and α- and β-▪. On the other hand, the Tseplyaev potential predicts a premature phase change of both UN and ▪ and cannot stabilize α- nor β-▪. However, the Kocevski potential cannot predict a stable α-U phase and is thus not suitable for the calculation of formation energies for non-stoichiometric point defects.

Synergistic Effect of Zn2+ Cation Doping and Te2− Anion Passivation on CsPbBrxI3‐x Nanocrystals for Efficient Perovskite Light‐Emitting Diodes

AbstractThe challenges of instability and surface defects in CsPbBrxI3‐x nanocrystals (NCs) pose significant limitations on their potential application in high‐performance pure‐red perovskite light‐emitting diodes (PeLEDs). Herein, a synergistic strategy of divalent cation (Zn2+) doping and anion (Te2−) passivation is proposed to solve these issues. Density functional theory analysis reveals that the synergistic effect can not only reduce the formation energy of CsPbBrxI3‐x NCs but also increase theiodide vacancy defect formation energy of CsPbBrxI3‐x NCs. Consequently, the optimized Zn2+/Te2− co‐modified CsPbBrxI3‐x NCs exhibit significantly enhanced stability with a near‐unity photoluminescence efficiency. Pure‐red PeLEDs based on these CsPbBrxI3‐x NCs possess outstanding spectral stability with a maximum external quantum efficiency and luminance of 16.1% and 1397.2 cd m−2, respectively. This synergistic strategy provides a new approach for enhancing the performance of mixed halide perovskite NCs and the corresponding optoelectronic devices.

First principles study on the electronic structure and optical properties of Janus WSeTe with defects and strains

A Janus monolayer can be described as a two-dimensional material with distinct anions on either side of each layer. Two of these distinct chalcogen atoms are situated in the mirror-symmetric lattice positions of the transition metal atoms and are referred to as Janus transition metal dichalcogenides (TMDs). This material breaks the out-of-plane mirror symmetry and thus has excellent properties not found in conventional TMDs. However, during material synthesis, it can generate a number of defects that can substantially alter its properties. Therefore, in this article, the changes in the electronic structure and optical properties of Janus WSeTe when generating single vacancy defects, double vacancy defects and antisite defects have been investigated using first principles study. Assess the stability of the material through computations of its phonon spectrum, AIMD simulation and defect formation energy. Analyse its bandstructure, projected density of states, and optical absorption coefficient to present the change in its properties. The results show that the easiest and most stable form of defect is the substitution of Se atom for Te atom. These defect types change the bandgap value in different ways in Janus WSeTe, which further changes the peak optical absorption coefficient. The lattice constants undergo alterations during the defect generation process. For this purpose, we also investigated the changes in the properties of Janus WSeTe and its defects when subjected to biaxial tensile and compressive strains ranging from −9% to 9 %. As the tensile and compressive strains increase, a gradual decrease in the band gap value is observed. Our findings may serve as a theoretical basis for experiments in the synthesis of Janus WSeTe and the development of electronic devices using monolayer Janus WSeTe.

A neural-network potential for aluminum

Aluminum and its alloys are most often used as structural materials due to their specific properties, such as low weight, low energy consumption for remelting and the possibility of almost complete processing. This paper utilizes machine learning, specifically the Behler-Parrinello neural network scheme, to develop a powerful potential for studying the underlying mechanisms of deformation, fracture, and defect formation. By surpassing the limitations of first principles calculations, the application of machine-learned potentials (MLP) becomes highly advantageous for describing pure aluminum (Al) in its solid and liquid phases. Specifically, from the generated potential equilibrium, thermodynamic, elastic, and vibrational properties of face-centered cubic (fcc) Al are obtained in very good agreement especially with density functional theory (DFT) results as well as with previous calculations using existing semi-empirical potentials, such as EAM and MEAM, recent machine-learned potentials, and experimental data. Furthermore, our potential proves to accurately reproduce defect formation energies such as previously computed and measured stacking-fault energy curves. Finally, stacking fault profiles as well as key quantities of the liquid phase such as the melting point at ambient pressure, temperature-dependent densities, and radial distribution functions are also calculated in very good agreement with the results from previous theoretical and experimental investigations. Nevertheless, our investigation goes beyond previous studies in proving excellent agreement with experimental data especially of the specific heat and the melting point at very high pressures. The competitive analysis performed in this work thus clearly demonstrates the validity and accuracy of the generated machine-learned potential to describe a wide range of properties of Al at various temperatures and pressures and thereby lays ground for future applications.

Li-Site Defects Induce Formation of Li-Rich Impurity Phases: Implications for Charge Distribution and Performance of LiNi0.5- xMxMn1.5O4 Cathodes (M = Fe and Mg; x = 0.05-0.2).

An understanding of the structural properties that allow for optimal cathode performance, and their origin, is necessary for devising advanced cathode design strategies and accelerating the commercialization of next-generation cathodes. High-voltage, Fe- and Mg-substituted LiNi0.5Mn1.5O4 cathodes offer a low-cost, cobalt-free, yet energy-dense alternative to commercial cathodes. In this work, the effect of substitution on several important structure properties is explored, including Ni/Mn ordering, charge distribution, and extrinsic defects. In the cation-disordered samples studied, a correlation is observed between increased Fe/Mg substitution, Li-site defects, and Li-rich impurity phase formation-the concentrations of which are greater for Mg-substituted samples. This is attributed to the lower formation energy of MgLi defects when compared to FeLi defects. Li-site defect-induced impurity phases consequently alter the charge distribution of the system, resulting in increased [Mn3+] with Fe/Mg substitution. In addition to impurity phases, other charge compensators are also investigated to explain the origin of Mn3+ (extrinsic defects, [Ni3+], oxygen vacancies and intrinsic off-stoichiometry), although their effects are found to be negligible.

First-principles study of oxygen defects in KH2PO4 crystal

This work investigates the electronic structures, defect formation energies and optical properties of charged oxygen vacancy and oxygen interstitial in KH2PO4 (KDP) crystals by First-principles. We find that the lattice distortion caused by VO is greater than that of Oi. For the neutral VO in the ferroelectric (FE) phase, the bond between H and O breaks and re-bonded in VO· system. In VO·· (The superscript represents the charged state, the ‘´’ represents negative charges and ‘·’ represents positive charges), the (PO3)−1 drags the neighboring (PO4)−3 over and bonded with the same O ion. Then it generates a large interstitial position in the structure, which makes it easy to introduce impurity interstitial. Small polaron makes electrons tend to be localized on two or three oxygen ions around the oxygen vacancy. Oxygen defects introduce new defect states in the band gap, which are mainly composed of the p-orbital of O ions. The defect formation energy of VO in two phases and Oi in the FE phase shows negative-U characteristics. Optical spectra indicate that the 467 nm luminescence band originates from the Oi′. The absorption band range from 163 nm to 246 nm is caused by vacancy and range from 212 nm to 428 nm by interstitial. The 200 nm and 285 nm absorption peaks originate from the F-centers (theVO capturing two electrons) and Oi′, respectively. We predict that oxygen defects will introduce additional UV absorption peaks such as 258 nm, 203 nm, 184 nm, and 163 nm, which significantly affect the optical threshold of KDP crystals.

Properties of radiation-induced point defects in austenitic steels: a molecular dynamics study

Austenitic steels are recognized as excellent structural materials for pressurized water reactors due to their outstanding mechanical properties and radiation resistance. However, compared to the widely studied FeCrNi series of steels, little is known about the radiation resistance of FeCrNiMn steel. In this study, the generation and evolution of radiation-induced defects in FeCrNiMn steel were investigated by molecular dynamics simulations. The results showed that more defect atoms were produced in the thermal spike stage, but fewer defects survived at the end of the cascades in FeCrNiMn compared to pure Fe. Point defect properties were analyzed by molecular statics, and the formation energies of defects in FeCrNiMn were lower than those of pure Fe, while the migration energies were higher. Compared to FeCrNi, FeCrNiMn had smaller migration energies and a larger overlap of vacancy and interstitial migration energies. The low vacancy formation energies and widely overlapping migration energies suggested that the number of point defects in the thermal spike stage was higher, but the possibility of recombination was greater. Additionally, Mn exhibited the smallest interstitial formation energies and migration energies. The difference in defect migration energies revealed that vacancy and interstitial defects migrate through different alloy constituent elements. This study revealed the underlying mechanism for the excellent irradiation resistance of FeCrNiMn.

Computational study of K vacancy with an H interstitial defect in [formula omitted] crystal

The electronic structures, defect formations, defect transition levels and optical properties for VK+Hi defect models in KDP crystals have been studied based on DFT. Lattice dynamics methods give the most reasonable compensation mechanism for VK, namely compensation with the third-nearest Hi neighbor from VK for the paraelectric (PE) phase and compensation with the fourth-nearest neighbor Hi from VK for the ferroelectric (FE) phase. The defect formation energies indicate that the (VK+Hi)x (The superscript represents the charged state, the ‘x’ represents neutral, ‘’’ represents −1 charge state and ‘.’ represents +1 charge state.) is the main defect type in this kind of defect cluster and a self-trapped electron is located at Hi in the (VK + Hi)′ system. For (VK+Hi)x system, one electron is accommodated in VK. There is not a new defect state in the band gap. The Hi bonds with the O ion (0.99 Å) form a hydroxyl. For (VK + Hi)′ system, the hydroxyl is broken, the Hi exists in an atomic form and introduces new defect states in the band gap. As the large relaxation energy leads to a large Huang-Rhys factor, the Stokes red shifts will significantly affect the optical properties. A broad ultraviolet (UV) absorption band and emission band range from UV to visible are obtained originating from the defect cluster. We believe that the far-violet absorption peaks (167 nm and 179 nm) caused by defect cluster VK+Hi can significantly impact the optical damage threshold of the KDP.

Enhanced carrier mobility and interface charge transfer in Bi–MoS2 heterojunctions induced by point defects

Semimetal Bi in contact with monolayer MoS2 (mMoS2) as a substrate reduced contact resistance. This phenomenon has attracted widespread attention. Presently, systematic research on defects in semimetal-TMDs heterojunctions remains limited. In this paper, nine types of vacancy defects (three S-vacancies at the heterojunction interface (VSI, II, III), three S-vacancies on the top layer (VSI, II, IIIt), one Mo vacancy (VMo), Mo–S double vacancies (VMo–S) and Mo–S triple vacancies (VMo–2S)) and defect-free structure (Perfect) are designed in mMoS2. Their impact on defect formation energy, Interface charge transfer, and carrier mobility in three-layer (3L)Bi(0001)-mMoS2 heterojunctions are studied by the First-Principles. The energy analysis indicates that in the 3LBi-mMoS2 contact, VS are more prone to formation than VMo, VSt, VMo–S and VMo–2S. At the same time VSⅡ has the lowest formation energy under Mo-rich environments. The analysis of electron and charge redistribution in the 3LBi-mMoS2 contact with defects indicates that defect generation introduces peaks at the Fermi level, enhancing the hybridization of Mo_4d and S_3p. The hybridization rate of electron orbitals in VMo surpasses that in VS and VSt, signifying that heterojunction structures with defects exhibit increased electron injection efficiency at the interface compared to Perfect. The charge carrier mobility of S and Mo defects in 3LBi-mMoS2 reveals a significant reduction in the effective mass of charge carriers due to vacancy defects. Due to the location of defects, heterojunctions exhibit anisotropy. Obtain Perfect > VMo > VSII (370.7 > 277>125.1 cm2V−1S−1) for the x-direction carrier mobility (μx), while VMo > Perfect > VSII (440.8 > 279.7>131.6 cm2V−1S−1) for the y-direction carrier mobility (μy). These findings offer practical insights for utilizing defects to modulate the electronic properties of Semimetal-MoS2 heterojunction interfaces.

Ion solvation free energy calculations based on first-principles molecular dynamics thermodynamic integration.

Numerous electrochemistry reactions require the precise calculation of the ion solvation energy. Despite the significant progress in the first-principles calculations for crystals and defect formation energies for solids, the liquid system free energy calculations still face many challenges. Ion solvation free energies can be calculated via different semiempirical ways, e.g., using implicit solvent models or cluster of explicit molecule models; however, systematically improving these models is difficult due to their lack of a solid theoretical base. A theoretically sound approach for calculating the free energy is to use thermodynamic integration. Nevertheless, owing to the difficulties of self-consistent convergence in first-principles calculations for unphysical atomic configurations, the computational alchemy approach has not been widely used for first-principles calculations. This study proposes a general approach to use first-principles computational alchemy for calculating the ion solvation energy. This approach is also applicable for other small molecules. The calculated ion solvation free energies for Li+, Na+, K+, Be2+, Mg2+, and Ca2+ are close to the experimental results, and the standard deviation due to molecular dynamics fluctuations is within 0.06eV.

Oxygen Vacancy-Laden Confinement Impact on Degradation of Metal Complexes.

Oxygen vacancies (Vo) have been recognized as the superior active site for PS-mediated environmental remediation; however, the formation and activation of Vo associated with the effects of chemical and spatial environments remain ambiguous. Herein, attributing to the low defect-formation energy of Vo in the presence of sulfonate groups, an in situ nucleating Vo-laden CuO nanosheet was deliberately fabricated inside the phase of a sulfonated mesoporous polystyrene substrate (Vo-CuO@SPM). The as-prepared nanocomposite demonstrated an excellent treatment efficiency toward metal complexes [Cu-EDTA as a case] with ignorable Cu(II) leaching, and it can be repeatedly employed for 25 recycles (not limited). Mechanistically, the electron transfer and the mass transport for PDS nonradical activation were proved to be substantially enhanced by the delocalized electrons and with the assistance of the microchannel environment. This work not only establishes insight into the formation of oxygen vacancies but also reveals the PS activation mechanism in the spatially confined sites.

Strain-modulated defect engineering of two-dimensional materials

Strain- and defect-engineering are two powerful approaches to tailor the opto-electronic properties of two-dimensional (2D) materials, but the relationship between applied mechanical strain and behavior of defects in these systems remains elusive. Using first-principles calculations, we study the response to external strain of h-BN, graphene, MoSe2, and phosphorene, four archetypal 2D materials, which contain substitutional impurities. We find that the formation energy of the defect structures can either increase or decrease with bi-axial strain, tensile or compressive, depending on the atomic radius of the impurity atom, which can be larger or smaller than that of the host atom. Analysis of the strain maps indicates that this behavior is associated with the compressive or tensile local strains produced by the impurities that interfere with the external strain. We further show that the change in the defect formation energy is related to the change in elastic moduli of the 2D materials upon introduction of impurity, which can correspondingly increase or decrease. The discovered trends are consistent across all studied 2D materials and are likely to be general. Our findings open up opportunities for combined strain- and defect-engineering to tailor the opto-electronic properties of 2D materials, and specifically, the location and properties of single-photon emitters.

Effects of oxygen vacancies on the structural, electronic, and optical properties of the photocatalytic InTaO4 compound

We conducted first-principles calculations based on density functional theory to investigate the impact of the oxygen vacancies on the structural, electronic, and optical properties of the InTaO4 compound. The latter is a famous photocatalytic semiconductor with its optical absorption in the visible range being an object of controversial interpretations. The presence of two types of isolated oxygen vacancies, O1 and O2, occupying 4g(1) and 4g(2) Wyckoff positions respectively, has been simulated within the frame of the supercell approach. Electronic structure and optical absorption (OA) have been calculated using the Becke-Johnson exchange-correlation potential. It is found that the presence of both types of vacancies generates defect states (DS) inside the band gap, primarily involving In-6s and O-2p states. The calculated valence-to-conduction-band band gap (4.25 eV) and DS-to-conduction-band band gap (2.5 eV) closely align with the experimentally determined OA edges for two onsets of InTaO4 absorption. The analysis of the calculated OA spectra leads to the conclusion that only O1 vacancy-induced absorption is consistent with the experimental OA, while O2 vacancy-induced absorption appears absent. This discrepancy probably arises from a higher concentration of O1 vacancies formed during crystal growth, attributed to the fact that the calculated defect formation energy of O1 vacancy is 0.258 eV lower compared to O2 vacancy. Consequently, the photocatalytic activity of InTaO4 is ascribed to intrinsic defects, primarily O1-type vacancies, though the influence of other defects cannot be entirely ruled out.

Defect Engineering for Enhanced Electrocatalytic Oxygen Reaction on Transition Metal Oxides: The Role of Metal Defects.

Metal defect engineering is a highly effective strategy for addressing the prevalent high overpotential issues associated with transition metal oxides functioning as dual-function commercial oxygen reduction reaction/oxygen evolution reaction catalysts for increasing their activity and stability. However, the high formation energy of metal defects poses a challenge to the development of strategies to precisely control the selectivity during metal defect formation. Here, density functional theory calculations are used to demonstrate that altering the pathway of metal defect formation releases metal atoms as metal chlorides, which effectively reduces the formation energy of defects. The metal defects on the monometallic metal oxide surface (Mn, Fe, Co, and Ni) are selectively produced using chlorine plasma. The characterization and density functional theory calculations reveal that catalytic activity is enhanced owing to electronic delocalization induced by metal defects, which reduces the theoretical overpotential. Notably, ab initio molecular dynamics calculations, ex situ XPS, and in situ ATR-SEIRAS suggest that metal defects effectively improve the adsorption of reactive species on active sites and enhance the efficiency of product desorption, thereby boosting catalytic performance.