Fluorine Termination Research Articles

Energy-efficient synthesis of Ti3C2Tx MXene for electromagnetic shielding

Traditional methods for synthesizing two-dimensional Ti3C2Tx MXenes such as hydrofluoric acid (HF) or LiF/HCl based etching can be time-consuming, complex, and often result in low yields. They generally involve multi-step processes involving >40 h of preparation time that can expose the materials to harsh conditions. In this study, we demonstrate a rapid single-step microwave (MW) synthesis method that significantly reduces production time to 90 min, achieving a 90 % yield and cutting energy consumption by 75 %. For the first time, synchrotron x-ray pair distribution function (PDF) analysis conducted on MW-synthesized MXene (MW-Ti3C2Tx) indicates greater structural fidelity in local atomic ordering, indicating high-quality which is comparable to conventionally synthesized counterparts (CO-Ti3C2Tx). This method achieves similar or greater structural quality in less time while also enhancing electromagnetic interference shielding (EMI SE) performance. A 15 μm MW-Ti3C2Tx film demonstrated an impressive EMI SE of ∼67 dB in the X-band, compared to the ∼63 dB achieved by CO-Ti3C2Tx. The enhanced EMI SE performance is attributed to the presence of fluorine terminations, which provide oxidation resistance, increased conductivity and improved absorption of EM waves. The MW-induced shocks during irradiation not only help remove O2/OH groups, preventing oxidation, but also tunes the functional groups, enhancing charge transport and effective EM wave attenuation. The MW synthesis method presents a fast, efficient, and scalable approach for producing high-quality MXene nanosheets, paving the way for advancements in EMI shielding and other applications.

Unmasking Fluorinated Moieties on the Surface of Hydride-Terminated Silicon Nanoparticles.

Despite the widespread use of hydrofluoric acid (HF) in the preparation of silicon surfaces, the true nature of fluorinated surface species remains unclear. Here, we employ an array of characterization techniques led by solid-state nuclear magnetic resonance spectroscopy to uncover the nature of fluorinated moieties on the surface of hydride-terminated silicon nanoparticles (H-SiNPs). A structural model that explains the observed trends in 19F and 29Si magnetic shielding is proposed and further supported by quantum chemical computations. Fluorine is incorporated into local oxidation domains on the surface and clustered at the interface of the oxide and surrounding hydride-terminated surface. Silicon sites capped by a single fluorine are also identified by their distinct 19F and 29Si chemical shifts, providing insight into how fluorine termination influences the electronic structure. The extent of fluorine passivation and the effects of fluorine on the optical properties of SiNPs are also discussed. Finally, challenges associated with Teflon contamination are highlighted that future explorations of nanomaterials may have to contend with.

Tailoring surface terminals on MXene enables high-efficiency electromagnetic absorption

MXene (Ti3C2Tx) is an important category of two-dimensional (2D) materials due to its distinctive metallic conductivity and adjustable surface chemistry. The exceptional benefits of heterointerface and defects or viods, combined with the distinct electromagnetic (EM) properties, inject boundless potential into the advancement of MXene-based absorbers for EM absorbing materials. However, conventional synthetic methods depend on chemical etching of MAX powders (Ti3AlC2) using hazardous HF or similar substances, resulting in MXene sheets with fluorine termination and limited stability in colloidal dispersions under ambient conditions. Herein, varied synthetic routes were proposed to prepare MXenes with different terminal groups by the fluoride-based salts, fluoride-free molten salts, and alkali etching. 2D MXene nanosheets with abundant surface groups are excellent EM absorbing materials, and the MXene etched by the Lewis acid CuCl2 delivered remarkable reflection loss (RL) value of −47.56 dB at 2.5 mm and broad bandwidth of 4.8 GHz due to promoted interfacial polarization. By conducting a thorough examination of the structural changes in MXenes, this study aims to propose a viable method for delaminating single-layer MXene and elucidate the EM absorption mechanisms.

Stoichiometric Ti3C2Tx Coating for Inhibiting Dendrite Growth in Anode‐Free Lithium Metal Batteries

Lithium metal batteries (LMBs) and anode‐free LMBs (AFLMBs) present a solution to the need for batteries with a significantly superior theoretical energy density. However, their adoption is hindered by low Coulombic efficiency (CE) and rapid capacity fading, primarily due to the formation of unstable solid electrolyte interphase (SEI) layer and Li dendrite growth as a result of uneven Li plating. Here, we report on the use of a stoichiometric Ti3C2Tx (S‐Ti3C2Tx) MXene coating on the copper current collector to enhance the cyclic stability of an anode‐free lithium metal battery. The S‐Ti3C2Tx coating provides abundant nucleation sites, thereby lowering the overpotential for Li nucleation, and promoting uniform Li plating. Additionally, the fluorine (−F) termination of S‐Ti3C2Tx participates in the SEI formation, producing a LiF‐rich SEI layer, vital for stabilizing the SEI and improving cycle life. Batteries equipped with S‐Ti3C2Tx@Cu current collectors displayed reduced Li consumption during stable SEI formation, resulting in a significant decrease in capacity loss. AFLMBs with S‐Ti3C2Tx@Cu current collectors achieved a high initial capacity density of 4.2 mAh cm−2, 70.9% capacity retention after 50 cycles, and an average CE of 98.19% in 100 cycles. This innovative application of MXenes in the energy field offers a promising strategy to enhance the performance of AFLMBs and could potentially accelerate their commercial adoption.

Surface termination effects on Raman spectra of Ti3C2Tx MXenes: an in situ UHV analysis.

Ti3C2Tx MXenes have typically a mixed surface termination of oxygen, hydroxyl and fluorine groups (Tx). In this work, we investigate the influence of the surface termination on the vibrational properties of Ti3C2Tx by performing thermal desorption and in situ Raman spectroscopy in ultra-high-vacuum (UHV). Significant changes in the Raman spectra occur after annealing above 600 °C, correlated with the desorption of approximately 80% of the fluorine termination, as confirmed by mass spectrometry and X-ray photoemission spectra. In particular, the intense Raman mode at 203 cm-1, usually attributed to a Ti-C-layer stretching vibration, is strongly damped upon fluorine desorption, while the broad spectral features between 220 and 680 cm-1, usually attributed to surface group vibrations, are not changing significantly. We show that the Raman spectra and the change induced by fluorine desorption are well represented by the phonon density of states instead of zone-center phonon modes. Disorder-induced Raman scattering strongly contributes to the Raman spectra. Moreover, due to the metallic nature of MXenes, charge density fluctuation scattering contributes as well. We show that the two scattering mechanisms, deformation potential and charge density fluctuation, may lead to opposite interpretations concerning the symmetry of the fluorine-related mode at 203 cm-1. This study provides new insights into the interpretation of the Raman spectra of MXenes, especially regarding the relation between surface chemistry and vibrational spectroscopy.

Antimicrobial Studies of Black Silicon and Black Diamond Using Gram‐Positive Bacteria

Herein, it is investigated if black diamond is useful in a bactericidal surface. Black diamond is derived from black silicon, a silicon surface structured into nanosized needles. Black diamond is obtained by coating black silicon with a thin diamond film, rendering the nanostructures more robust. The bactericidal and antibacterial properties of fluorine‐terminated and hydrogen‐terminated black diamonds with those of black silicon and for flat surfaces of diamond (on silicon) with the same terminations are studied. The ability to repel and kill Gram‐positive Staphylococcus aureus and Staphylococcus epidermidis is evaluated, which have a thicker cell wall and are more mechanically robust than the bacteria that are studied before. The initial adhesion as well as long‐term 24 h biofilm formation is studied. The number of bacteria that initially adhere to the fluorine‐terminated black diamond surface is reduced and has the highest dead bacterial ratio. Biofilm formation after 24 h shows that while all surfaces outperform glass over the long term, diamond‐coated surfaces with both fluorine and hydrogen termination have a significant inhibiting biofilm formation effect. In conclusion, fluorinated and hydrogenated diamond‐coated surfaces with and without nanoneedles have repelling, bactericidal, and biofilm‐inhibiting effects on Gram‐positive bacterial strains and are promising antimicrobial surfaces.

MXene‐Based Anode‐Free Magnesium Metal Battery

AbstractRechargeable magnesium batteries (RMBs) are promising next‐generation low‐cost and high‐energy devices. Among all RMBs, anode‐free magnesium metal batteries that use in situ magnesium‐plated current collectors as negative electrodes can afford optimal energy densities. However, anode‐free magnesium metal batteries have remained elusive so far, as their practical application is plagued by low Mg plating/stripping efficiency due to nonuniform Mg deposition on conventional anode current collectors. Herein, for the first time, an anode‐free Mg‐metal battery is developed by employing a 3D MXene (Ti3C2Tx) film with horizontal Mg electrodeposition. The magnesiophilic oxygen and reactive fluorine terminations in MXene enable an enriched local magnesium‐ion concentration and a durable magnesium fluoride‐rich solid electrolyte interphase on the Ti3C2Tx film surface. Meanwhile, Ti3C2Tx MXene exhibits a high lattice geometrical fit with Mg (≈96%) to guide the horizontal electrodeposition of Mg. Consequently, the developed Ti3C2Tx film achieves reversible Mg plating/stripping with high Coulombic efficiencies (>99.4%) at high‐current‐density (5.0 mA cm−2) and high‐Mg‐utilization (50%) conditions. When this Ti3C2Tx film is coupled with a pre‐magnesized Mo6S8 cathode, the anode‐free Mg‐metal full‐cell prototype exhibits a volumetric energy density five times higher than its standard Mg‐metal counterpart. This work provides insights into the rational design of anode current collectors to guide horizontal Mg electrodeposition for anode‐free Mg metal batteries.

Ti3−yNbyC2Tx MXenes as high-rate and ultra-stable electrode materials for supercapacitors

Despite being a promising supercapacitor electrode material, the development of Ti3C2Tx has still been limited by many obstacles, such as restacking Ti3C2Tx nanosheets and non-electrochemically active fluorine terminations on the surface. Herein, new double transition metal Ti3−yNbyC2Tx MXenes are prepared by etching Ti3−yNbyAlC2 solid solution MAX precursors obtained by self-propagating high-temperature synthesis method for the first time. The synthesized Ti3−yNbyC2Tx MXenes exhibit larger interlayer spacing and more surface -O terminations than Ti3C2Tx, resulting in superior rate performance and high cycling stability as supercapacitors electrode materials. In particular, Ti2.9Nb0.1C2Tx demonstrates a high volumetric specific capacity of 1014 F cm−3 at a scan rate of 2 mV s−1, superior rate performance with a volumetric specific capacity of 422 F cm−3 at a scan rate of 2000 mV s−1, and ultra-long cycling life up to 84000 cycles at a current density of 10 A g−1. This work expands the practical applicability of the MXenes family in energy storage applications and provides a promising strategy to tailor the MXenes interlayer structure and surface chemistry.

Synthesis and in situ sulfidation of molybdenum carbide MXene using fluorine-free etchant for electrocatalytic hydrogen evolution reactions

Synthesizing MXenes from Mn+1AXn (MAX) phases using hazardous hydrogen fluoride is a common and effective method. However, fluorine termination on the basal planes and edges of the resulting MXenes is undesirable for the electrocatalytic hydrogen evolution reaction (HER), while oxygen (O), hydroxyl (OH), and sulfur (S) termination favors this reaction. Herein, we unveil a simple fluorine-free exfoliation and two-step vulcanization method for synthesizing molybdenum sulfide-modified molybdenum carbide (MoS2/Mo2CTx MXene, T = OH, O, S) for the HER in alkaline medium. Microwave-assisted hydrothermal treatment of the MAX phase (Mo3AlC2) with sodium hydroxide-sodium sulfide as an etching solution and thioacetamide as a source of sulfide ions enabled the selective dissolution of the aluminum (Al) layer and sulfidation of the surface Mo atoms to form amorphous MoS2. Thus, the vulcanization of Mo2CTx MXene resulted in the formation of MoS2/Mo2CTx MXene. The MoS2 formed on the surface of Mo2CTx provided enhanced stability by preventing oxidation. MoS2/Mo2CTx exhibited enhanced electrocatalytic activity toward the HER, mainly due to the O, OH, and amorphous MoS2 functionalities. The MoS2 sites on the surface exhibited an overpotential of 110 ± 7 mV at a current density of 10 mA cm−2 as a result of enhanced charge transfer and mass transfer. Thus, the sulfidation method demonstrated herein is capable of producing amorphous MoS2 structures on Mo2CTx MXene, which could be applied for the surface modification of other molybdenum-based nanomaterials or electrocatalysts to improve stability and enhance electrocatalytic activity.

Fluorination of the silicon-terminated (100) diamond surface using C60F48

Fluorination of the silicon terminated (100) diamond surface under ultra-high vacuum using a molecular fluorine source (C60F48) is investigated with a combination of high resolution photoelectron spectroscopy and low energy electron diffraction. The C60F48 fluorinates the dangling bonds of the silicon-termination on contact, resulting in an inhomogeneous fluorine termination, which remains when the C60F48 is removed by a 550 °C anneal. Despite removing approximately 50% of the surface silicon in the process, the two domain (3 × 1) surface symmetry of the silicon-terminated (100) surface is retained. When exposed to ambient conditions, while some fluorine is displaced by atmosphere exposure, partial fluorination remains. While further optimsation of this process is required for fluorinating diamond in cases where homogeniety and minimised surface damage are desirable, this work demonstrates the potential of the silicon-terminated (100) diamond surface for enabling engineering of the surface properties of diamond.

The Importance of Stacking and Coordination for Li, Na, and Mg Diffusion and Intercalation in Ti3C2T2 MXene

AbstractThe 2D layered Ti3C2T2 MXene is known for its diverse chemistry and has been investigated as potential anode and cathode in Li, Na, and Mg batteries. Ti3C2T2 layers can stack in at least two different ways depending on the termination group chemistry. In addition, stacking and termination groups influence the diffusivity and energy of ions intercalated in the MXene. How stacking influences the diffusivity, and how intercalated ions influence the stacking stability are not fully understood. In this study, density functional theory simulations explore Li, Na, and Mg ions intercalated in Ti3C2T2 stacked in four different ways; two are experimentally verified, and previously discussed in literature, and two with limited experimental evidence. It is shown that the stacking can reduce diffusion by 8–20 orders of magnitude. It is also explained how the termination group chemistry and the intercalated Li/Na/Mg ions change the relative stability of the stackings. The stacking's influence on diffusion properties is explained by examining the coordination of the ions at different points along the migration path. It is suggested that Ti3C2T2 with significant fluorine termination can be well‐suited for especially Na anode use, and regardless of termination is unsuited as Mg cathode.

S-doped multilayer niobium carbide (Nb4C3Tx) electrocatalyst for efficient hydrogen evolution in alkaline solutions

Developing highly efficient and low cost electrocatalysts for hydrogen evolution reaction (HER) is a popular topic for electrocatalytic water splitting to hydrogen technology. Herein, we report a novel heterostructure electrocatalyst prepared by the S-doping multilayer niobium carbide (S-ML-Nb4C3Tx) through hydrothermal technique. Compared with pristine ML-Nb4C3Tx catalyst, the as prepared electrocatalyst presents remarkable catalytic activity for HER with lower overpotential of 118 mV@10 mA/cm2 and a Tafel slope of 104 mV dec−1 in 1.0 M KOH solution. In addition, the catalyst exhibits a stable electrochemical durability of as long as 24 h in 1.0 M KOH. Efficient HER ability of the S-ML-Nb4C3Tx catalyst is mainly attributed to the following points: Firstly, the ML-Nb4C3Tx with superior conductivity and stability can effectively avoid the aggregation and oxidation. Secondly, the conversion of fluorine termination groups to –OH by TMAOH treatment can expose more active sites. Further, after the S-doping by hydrothermal reaction, NbS2 nanoparticles can prevent the ML-Nb4C3Tx nanosheets from restacking. As a result, the enlarged interlayer spacing and porous structure of the catalyst are conducive to the charge transfer. In addition, the introduction of NbS2 nanoparticles on the surface of ML-Nb4C3Tx can form heterostructure and subsequently adjust the electronic structure of the catalyst, accelerate the electron transfer, and improve the HER performance. This work presents a new strategy for the designing and preparation of low cost MXene-based catalysts for HER application.

Encapsulation of Metallic Zn in a Hybrid MXene/Graphene Aerogel as a Stable Zn Anode for Foldable Zn-Ion Batteries.

A 3D host can effectively mitigate the dendritic growth of a zinc (Zn)-metal anode. However, the increased electrode/electrolyte reaction area using the 3D substrate accelerates the passivation and corrosion at the anode interface, ultimately degrading the electrochemical performance. Here, an oriented freezing process is used to create a flexible MXene/graphene scaffold. Based on the abundant zincophilic traits and micropores in the structure, Zn is densely encapsulated inside the host by the electrodeposition process. During cycling, the composite anode endows an in situ solid electrolyte interface with zinc fluoride at the electrode/electrolyte interface due to inherent fluorine terminations in MXene, efficiently inhibiting the dendritic growth. Furthermore, the design wherein bulk Zn is distributed in a 3D microscale manner suppresses hydrogen evolution reactions (3.8mmol h-1 cm-2 ) and passivation, through in/ex situ tests. As a result, in a symmetrical cell test, the electrode has a long-cycling life of over 1000 h at 10mA cm-2 . After continuous single folding followed by double folding, a quasi-solid-state foldable cell with the composite anode and a LiMn2 O4 cathode (60% depth of discharge) maintains high-capacity retention of over 91%. This research presents a revolutionary encapsulating idea for aqueous Zn-ion batteries, as well as foldable investigation.

Design single nonmetal atom doped 2D Ti2CO2 electrocatalyst for hydrogen evolution reaction by coupling electronic descriptor

2D MXenes, with large surface area, good conductivity, adjustable hydrophilic and varies surface functional groups, are potential catalyst for hydrogen evolution reaction (HER). In this work, 14 kinds of nonmetal (NM) single atom doped 2D Ti2CO2 catalysts were screened by DFT method. It was found that the surface doping of nonmetal single atom can effectively promote the HER activity of Ti2CO2. Among them, Ti2CO2 with rich fluorine termination groups realizing efficient electrocatalytic HER has been successfully verified by recent experiments. Through the analysis of electronic structure, it is found that nonmetal single atom valence electron number and bader electron transfer coupled electron descriptor is suitable to accurately predict the trend of 2D NM-Ti2CO2 catalytic activity for HER. The large-scale screening of this work and the mechanism analysis of nonmetal single atom surface doping enhanced of 2D Ti2CO2 HER activity not only provide a database reference for the experimental synthesis of NM-MXenes HER catalyst, but also provide a electronical mechanism guidance for the extensive design of new NM- MXenes materials.

Ambient‐Stable Two‐Dimensional Titanium Carbide (MXene) Enabled by Iodine Etching

AbstractMXene (e.g., Ti3C2) represents an important class of two‐dimensional (2D) materials owing to its unique metallic conductivity and tunable surface chemistry. However, the mainstream synthetic methods rely on the chemical etching of MAX powders (e.g., Ti3AlC2) using hazardous HF or alike, leading to MXene sheets with fluorine termination and poor ambient stability in colloidal dispersions. Here, we demonstrate a fluoride‐free, iodine (I2) assisted etching route for preparing 2D MXene (Ti3C2Tx, T=O, OH) with oxygen‐rich terminal groups and intact lattice structure. More than 71 % of sheets are thinner than 5 nm with an average size of 1.8 μm. They present excellent thin‐film conductivity of 1250 S cm−1 and great ambient stability in water for at least 2 weeks. 2D MXene sheets with abundant oxygen surface groups are excellent electrode materials for supercapacitors, delivering a high gravimetric capacitance of 293 F g−1 at a scan rate of 1 mV s−1, superior to those made from fluoride‐based etchants (<290 F g−1 at 1 mV s−1). Our strategy provides a promising pathway for the facile and sustainable production of highly stable MXene materials.

Ambient-Stable Two-Dimensional Titanium Carbide (MXene) Enabled by Iodine Etching.

MXene (e.g., Ti3C2) represents an important class of two‐dimensional (2D) materials owing to its unique metallic conductivity and tunable surface chemistry. However, the mainstream synthetic methods rely on the chemical etching of MAX powders (e.g., Ti3AlC2) using hazardous HF or alike, leading to MXene sheets with fluorine termination and poor ambient stability in colloidal dispersions. Here, we demonstrate a fluoride‐free, iodine (I2) assisted etching route for preparing 2D MXene (Ti3C2Tx, T=O, OH) with oxygen‐rich terminal groups and intact lattice structure. More than 71 % of sheets are thinner than 5 nm with an average size of 1.8 μm. They present excellent thin‐film conductivity of 1250 S cm−1 and great ambient stability in water for at least 2 weeks. 2D MXene sheets with abundant oxygen surface groups are excellent electrode materials for supercapacitors, delivering a high gravimetric capacitance of 293 F g−1 at a scan rate of 1 mV s−1, superior to those made from fluoride‐based etchants (<290 F g−1 at 1 mV s−1). Our strategy provides a promising pathway for the facile and sustainable production of highly stable MXene materials.

Photoelectrochemical performance of TiO2 photoanodes: Nanotube versus nanoflake electrodes

In the present work, we compare the photoresponse of vertically erected (VE) single crystal anatase layers with that of widely used TiO2 nanotube layers. These VE-anatase layers were grown hydrothermally, directly on fluorine-doped tin oxide (FTO) glass, and consist of an array of anatase single crystal flakes with preferred (001) facets. As formed, these single crystal layers are fluorine terminated – this termination can be removed by a thermal treatment in air. We compare the photocurrent magnitude and photocurrent transients using intensity-modulated photocurrent spectroscopy (IMPS). We find that the “de-fluorinated” VE-anatase layers show significantly higher photocurrents than the comparable nanotube layers. This high efficiency of the VE-anatase layers is due to the electron transport being 100 times faster in these single crystal electrodes, provided that the blocking fluorine termination is removed.

Over 59 mV pH−1 Sensitivity with Fluorocarbon Thin Film via Fluorine Termination for pH Sensing Using Boron‐Doped Diamond Solution‐Gate Field‐Effect Transistors

pH sensing facilitates many substantial aspects of the society such as chemical laboratory analysis, agriculture, or water and soil qualities. However, existing pH sensors have problems and limitations such as fragility, hysteresis, or slow responding time. In this research, a new method utilizing fluorocarbon thin film via fluorine termination and boron‐doped diamond (BDD) solution‐gate field‐effect transistors (SGFETs) for pH sensing is developed for the first time. The fluorocarbon film device demonstrates a high pH sensitivity of 67.4 and 34.9 mV pH−1 in acid and alkaline pH regions, respectively.

Stable Electrochemical Li Plating/Stripping Behavior by Anchoring MXene Layers on Three-Dimensional Conductive Skeletons.

The ultrahigh specific capacity of lithium (Li) metal makes it possible to serve as the ultimate candidate for an anode in high-energy density secondary batteries, whereas the safety hazards caused by Li dendrite growth severely hamper the commercialization process of a lithium metal anode. Here, we propose a 3D conductive skeleton by anchoring MXene on Cu foam (MXene@CF) to significantly improve the electrochemical Li plating/stripping behavior. Li metal tends to nucleate uniformly and grow horizontally along the MXene nanosheets under the strong Coulomb interaction between adsorbed Li and MXene. Moreover, the abundant fluorine termination groups in MXene contribute to forming a stable fluorinated solid electrolyte interphase (SEI) and thus effectively regulating the Li deposition behaviors and prolonging the stability of the Li metal anode. Therefore, the MXene@CF skeleton maintains a high Coulombic efficiency (CE) of 98.5% after 200 cycles at 1 mA cm-2. The MXene@CF-based symmetric cells can run for more than 1000 h without intense voltage fluctuation and demonstrates remarkable deep charge/discharge abilities. The MXene@CF-Li|LiFePO4 full cell exhibits outstanding long-term cycling stability (95% capacity retention after 300 cycles). Our research suggests that MXene could effectively regulate the Li plating behavior that might provide a feasible solution for a dendrite-free Li anode.

Interface defect engineering for high-performance MOSFETs with novel carrier mobility model: Theory and experimental verification

As the conventional hydrogen-termination method has a limited ability to improve the interface quality between SiO2 and its Si substrate, an alternative termination method to reduce the influence of interface states is necessary. Interface engineering using first-principles calculations to suppress the influence of interface states is proposed based on the findings that silicon with dangling bonds is their primary origin. First-principles calculations indicate that the interface states can be terminated with oxygen when incorporated into the SiO2/Si interface without additional oxidation, which generates other interface states from an appropriate oxygen-anneal process. It is experimentally shown that such an oxygen termination can be realized in slow and low-temperature annealing, and the oxygen-termination method is a promising alternative for hydrogen termination. The stronger Si–O bond introduced from the oxygen termination compared with the Si–H bonds from hydrogen termination ensures a better interface quality. As one oxygen atom terminates two silicon atoms, the oxygen-termination method can efficiently suppress the number of interface defects compared with hydrogen and fluorine termination. The mobility degradation due to the interface states was improved more from oxygen termination than from hydrogen termination because the strength of Coulomb scattering due to Si–O dipoles is reduced from the heavier oxygen mass. Theoretical predictions were verified using experiments, indicating that the oxygen-termination method under appropriately optimized annealing conditions (speed and temperature) is a promising candidate to improve the interface quality by reducing the influence of interface states.