Substitution Of Oxygen Research Articles

Surface-Stabilized High-Entropy Layered Oxyfluoride Cathode for Lithium-Ion Batteries.

High-entropy materials have been demonstrated to improve the structural stability and electrochemical performance of layered cathode materials for lithium-ion batteries (LIBs). However, structural stability at the surface and electrochemical performance of these materials are less than ideal. In this study, we show that fluorine substitution can improve both issues. Here, we report a new high-entropy layered cathode material Li1.2Ni0.15Co0.15Al0.1Fe0.15Mn0.25O1.7F0.3 (HEOF1) based on the partial substitution of oxygen with fluorine in previously reported high-entropy layered oxide LiNi0.2Co0.2Al0.2Fe0.2Mn0.2O2. This new compound delivers a discharge capacity of 85.4 mAh g-1 and a capacity retention of 71.5% after 100 cycles, showing significant improvement from LiNi0.2Co0.2Al0.2Fe0.2Mn0.2O2 (first 57 mAh g-1 and 9.8% after 50 cycles). This improved electrochemical performance is due to suppression of the surface M3O4 phase formation. Although still an early stage study, our results show an approach to stabilize the surface structure and improve the electrochemical performance of high-entropy layered cathode materials.

Mechanistic study in sulfur-carbon co-modification on Li2FeSiO4 for lithium-ion batteries

Lithium iron silicate (Li2FeSiO4) has high theoretical capacity of 332 mAh∙g-1 upon full extraction of two lithium ions, which is accompanied by high delithiation potential and large volume change. Sulfur modification could be an effective approach for stabilizing Li2FeSiO4 cathodes. A series of carbon-coated Li2FeSiO4 samples were prepared through a hydrothermal and solid-state reaction route at a fixed sucrose content (14 wt% carbon) with varying amounts of sublimed sulfur at 5, 10, 15, 20 and 25 at%. The crystal structures, chemical compositions, microstructures and electrochemical performances of the differently sulfur-modified Li2FeSiO4/C were systematically investigated. The sulfur-carbon co-modifications and possible existing chemical states of sulfur are discussed in terms of the surface and near-bulk modifications. It was found that all the samples exhibited a monoclinic P21 structural Li2FeSiO4, while the sulfur contents over 10 at% formed impure phases such as iron sulfides (Fe1-xS) and lithium metasilicate (Li2SiO3). Furthermore, three types of sulfur states could be found when sulfur and carbon were added simultaneously into Li2FeSiO4. The surfaces were predominated by S–C and S–O–C, indicating the sulfur-carbon co-modification, which would reduce the resistance at the solid/electrode interface (SEI) but increase the charge transfer resistance. Near the bulk, the enhanced interactions between sulfur and iron S–Fe(−S) or sulfur and silicon S–Si(−O) may lead to the formation of possible impurities or oxygen substitution by sulfur. The former is detrimental as the effective sulfur amount is reduced, while the latter is beneficial to improve specific capacity and cycle stability. The overall performance of sulfur-carbon co-modified sample is influenced complicatedly by the sulfur content. The best initial discharge capacity of 152.3 mAh∙g-1 was obtained with 5 at% sulfur modification, while the best overall performance, showing a typical warm-up response and good cycle stability, was observed with 15 at% sulfur modification.

Nanoscale homojunction thermoelectric generator built in defect-engineered MoS2

The relatively low efficiency and costly composition of conventional thermoelectric generators (TEGs) hinder pragmatic usage despite their high Carnot efficiency. A PN-junction-based TEG is one candidate to resolve the noted drawbacks, but electron-hole recombination at the junction severely reduces the efficiency and limits the compactness. Here, we propose the nanoscale homojunction thermoelectric generator by engineering the ${\mathrm{MoS}}_{2}$ grain boundary. Ab initio scanning Seebeck microscopy revealed that the influence of deep-level wave functions of atomic defects broadens out to a nanoscale, leading to the doping-tunable Seebeck domain with a different magnitude or even inverted sign. This thermopower utilization using vestiges of localized defect states enables exceptional integration density in a single material, while the simple oxygen substitution inflates the efficiency by barricading the recombination at the junction. Our finding suggests that inevitable structural defects could pave the way for actualizing productive thermoelectric energy recycling at the nanoscale.

Impact of fluorine and chlorine doping on the structural, electronic, and optical properties of SnO2: first-principles study

In this work, we carried out in-depth study of the structural, electronic, and optical properties of intrinsic, fluorine (F)- and chlorine (Cl)-doped SnO2, using a pseudo-potential plane-wave scheme in the framework of the density functional theory. We found that the substitution of oxygen by F or Cl elements slightly modified the crystalline parameters without altering the stability of SnO2 compounds. The doping of tin oxide by these two halogens is confirmed by the displacement of the Fermi level position to the conduction band. Consequently, the doped materials are strongly degenerated as illustrated by the Moss-Burstein shift: 2.310 and 2.332 eV for F:SnO2 and Cl:SnO2, respectively. On the other hand, the density of states and Mulliken population analysis show that the covalent character of Sn–O bond is maintained after doping, while Sn–X (X = F or Cl) bond reveals an ionic nature. In terms of optical properties after doping, intrinsic SnO2 exhibits low absorption, while the doped ones are transparent in the visible range, making them more efficient in photovoltaic applications. Moreover, in the ultraviolet (UV) scale, pure and doped tin oxide compounds show better absorption, which may be beneficial for use in devices of protection against UV light and UV absorbers or sensors. Finally, the plasma frequencies of 28.22, 29.16, and 27.67 eV for pure, F-, and Cl-doped SnO2, respectively, were obtained.

Gradient oxygen-injecting MoS2 nanosheets catalyst boosting reductive C-N coupling of nitroarenes: Mechanistic insight into activity reconstruction

It is very appealing to be able to improve the intrinsic activity of a low-cost MoS2 catalyst and broaden the adaptability of substrates in heterogeneous catalytic C-N bond formation from nitro compounds. A gradient oxygen-injection method was used in this study to regulate the electronic structure of the in-plane Mo site in the inert basal plane of the 2H-MoS2 nanosheet, resulting in a remarkable activity reconstruction in the reductive C-N coupling of nitroarenes with aromatic boronic acids. In the lattice of MoS2, gradient oxygen substitution results in structured changes of the in-plane Mo site, including crystal distortion brought on by asymmetric coordination and additive intergrown interfacial MoS2 and MoO3, which in turn contributes to the synergistic highly-active reactive sites of MoS2. Additionally, the interesting secondary activity reconstruction of the catalyst in the toluene solvent during the reaction canreplace partial S sites with reactive intermediate oxygen, which results in a subsequent improvement in activity of the used catalyst. The effectiveness of the modified catalyst and the crucial role of the introduced oxygen concentration and alternate position around the Mo site of MoS2 in determining the adsorption and activation of nitro compound were validated through the implementation of various reaction experimental controls and density functional theory calculations. The N-O bond of nitrobenzene was specifically made weaker and easier to break by the addition of adjacent oxygen atoms around the Mo center, which aided the subsequent coupling process. Through altering the coordination environment of the active metal in the reductive coupling reaction of nitroarenes, this work offers some novel findings and new insights into the activity reconstruction of Mo-based catalysts.

Enhancing charge storage of O-doped perovskite fluorides via in-situ electrochemical oxidation for high-performance potassium-ion capacitors

Potassium ion capacitors (PICs) are regarded as promising large-scale aqueous energy storage systems. However, due to the poor K+ transport kinetics and the structural instability of the cathode materials, the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs. Herein, a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs, introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode. During the electrochemical oxidation process, it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF3 (KxMnFyOz), realizing a structural reconstruction at the electrode material/electrolyte interface. The First-principles calculations based on density functional theory (DFT) are performed to confirm that the improved electrical conductivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine. The obtained K1.14MnF1.17O1.26 cathode achieves a high specific capacitance of 694 F g–1 at 1 A g–1, as well as high capacitance retention of 91.3% after 10,000 charge/discharge cycles in mild K2SO4 electrolyte. This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.

Tailoring the three-phase microenvironment surface to induce carbon nitride oxide generating ·O2– with 100% selectivity for ultrafast photodegradation tetracycline under visible light

The reactive oxygen species (ROS) contribute to photodegrading tetracycline (TC), which determines the overall efficiency of photocatalysts. Superoxide radical (·O2–) is one of the excellent ROS for photodegrading TC by carbon nitride. However, achieving hierarchical carbon nitride with efficient, stabile, and selective production of ·O2– via O2 photoreduction is a great challenge. Herein, a carbon nitride oxide nest (CNON6) with carbon/nitrogen vacancies (C-v, N-v) and oxygen substitution (O-s) was prepared via tailoring surface microenvironment. The CNON6 can photodegrade 82% of TC within 2 min under visible light, and the pseudo-first-order kinetic constant is 1.22 min−1, 24-fold higher than that of CN. The superior photoactivity is attributed to a unique surface microenvironment, which N-v increased photoelectric conversion efficiency, C-v enhanced O2 adsorption and O-s induced ·O2– evolution with ∼ 100% selectivity. Moreover, PVDF membrane-supported CNON6 (11.33 cm2, 0.88 mg/cm2) can completely remove TC from wastewater at a rate of 2.62 mg/h in a simulated industrial continuous flow cell. The cost-effectiveness assessment was $6.36/kg/h, implying the CNON6/PVDF has a bright application prospect in wastewater treatment. This work developed a surface microenvironment tailor strategy to design photocatalysts for efficient degradation of TC.

High temperature stability and sintering resistance of Gd2O3-Yb2O3-Y2O3-ZrO2 (GYYZO) coating

Solid-solution agglomerated ZrO2-based powders co-doped with Gd2O3, Yb2O3 and Y2O3 rare earth oxides were synthesized by solid-phase sintering and spray drying. The corresponding GYYZO coating was prepared by using atmospheric plasma spraying, while the 8YSZ coating was also prepared as a control group for the high temperature performance investigation. The high temperature structure and phase stability as well as the sintering resistance of both coatings were investigated by SEM, XRD, DSC, EPMA and TEM observations. The results showed that the 8YSZ coating began to undergo a phase transition of tetragonal (t) phase to monoclinic (m) after 50 h heat treatment at 1400 °C, while the GYYZO coating remained free of phase transition even heat-treated for up to 200 h, demonstrating a better phase stability. In addition, as an indicator of sintering resistance of the coating, the porosity of the 8YSZ coating decreased up to 90.1 % after 200 h heat treatment, while that of the GYYZO coating decreased only 20.6 %. The superior high temperature performance of GYYZO coating can be explained by the pinning effect of nano-pores on grain boundaries. The formation of nano-pores was associated with the evolution of defect clusters in the coating, which were facilitated by the substitution defects and oxygen vacancies created by the GdYb co-doping. During the heating process, these clusters migrated along with the grain boundaries and formed pearl-string-like nano-pores at the grain boundaries. The eventual formation of nanopores not only further inhibits grain boundary migration to reduce sintering, but also prevents the segregation of Y elements to hinder t-phase to m-phase transition.

Comparative study on structure and electronic properties of Al0.5Ga0.5N thin film and nanowire photocathode under surface oxidation

Oxidation will generate higher surface barriers and new surface states, resulting in declined electron escape probability and electron emission performance, which seriously affects surface activation effect of the photocathode. In order to explore the effects of oxidation on Al0.5Ga0.5N thin film photocathodes and nanowire photocathodes, we have analyzed structure and electronic properties of Al0.5Ga0.5N thin film and nanowire under oxidation. The results show that formation energies of Al0.5Ga0.5N film oxidation surface is negative in both O-rich and O-poor conditions under O adsorption, indicating that surface of Al0.5Ga0.5N film is easily oxidized. However, Al0.5Ga0.5N nanowires are easily oxidized only when O concentration is higher. The formation energies of oxygen substitution model are all positive, indicating that this form of oxide is not easy to form on the surface. The results of band structure and PDOS indicate that pristine Al0.5Ga0.5N film has abundant surface states near the Fermi level. After oxygen adsorption, Ga atoms form stable Ga–O bonds with O atoms and the surface states are weakened. For oxygen substitutional oxidation, compared to Al0.5Ga0.5N thin film, conduction band of Al0.5Ga0.5N nanowire splits to form more energy levels and CBM moves downward, forming an n-type surface, which is not conducive to photoelectric emission.

Tailoring the electronic structure of ZnCo2O4 by incorporating anions with low electronegativity to improve the water oxidation activity

Electron configurations and conductivity are significant descriptors/characteristics for the oxygen evolution reaction (OER), which can be modulated with heteroatom doping. Given that metal substitution usually reduces the number of active sites of spinel electrocatalysts, the effect of anion doping on the electronic structure has been investigated by using ZnCo2O4 (ZCO) as a demonstration. Compared with Co3+-dominated ZCO, the substitution of oxygen with less electronegative sulfur raises the portion of Co2+ in the low-spin states (t2g6eg1), which is more OER-active than Co3+ (t2g6eg0). Co2+ in the sulfur-doped ZCO (ZCO-S) is associated with the redistribution of electron density from S toward Co due to the high covalent interaction of Co—S. The Co—S interaction also induces a fast charge transfer. ZCO-S outperforms pristine ZCO by 11 times in terms of specific OER activity at 1.65 V versus reversible hydrogen electrode. In contrast, doping fluorine with higher electronegativity and valence deteriorates OER activity. Our work establishes the correlation between the electronegativity of anion dopants and OER intrinsic activity in spinel oxides and provides a simple and effective method to modulate the electronic structure of spinel oxides by doping anions with different electronegativities, which can be a new avenue for the rational design of high-performance spinel electrocatalysts.

Low-valence B-site cation substitution triggering polarization and oxygen vacancy enhancement for elevating piezocatalytic activity on Bi2MoO6

Piezocatalysis, as a rising star in catalysis, shows bright application prospects, but also has the issues of low catalytic efficiency, which is mainly derived from rapid charge recombination and insufficient catalytic reactive sites. In order to address the above two challenges, we select a layered perovskite Bi2MoO6 as the piezocatalyst model, and introduce the low-valence B-site cations I5+ and V5+ with similar ionic radius to substitute for Mo6+ in the MoO6 octahedra, which induce the distortion of MoO6 octahedra and introduction of more oxygen vacancies in Bi2MoO6 simultaneously. The replacement results in strengthened ferroelectric remanent polarization and piezoelectric properties, in which the piezoelectric coefficient of Bi2MoO6 increases to 1.69 and 1.36 times, respectively, when the optimal amounts of I5+ and V5+ is introduced into Bi2MoO6. At the same time, a higher concentration of oxygen vacancies is generated due to the charge compensation effect, which promotes the adsorption and activation of O2 on the surface of Bi2MoO6, and is conducive to the generation of reactive species. Benefiting from these advantages, the piezocatalytic performance for the degradation of various organic pollutants and antibiotics has been effectively heightened. This work illustrates the superiority and universality of nonequivalent cation substitution in improving piezocatalysis, and provides a reference for synergistic strategies to enhance piezocatalytic performance.

The impact of the chalcogen-substitution element and initial spectroscopic state on excited-state relaxation pathways in nucleobase photosensitizers: a combination of static and dynamic studies.

The substitution of oxygen with chalcogen in carbonyl group(s) of canonical nucleobases gives an impressive triplet generation, enabling their promising applications in medicine and other emerging techniques. The excited-state relaxation S2(ππ*) → S1(nπ*) → T1(ππ*) has been considered the preferred path for triplet generation in these nucleobase derivatives. Here, we demonstrate enhanced quantum efficiency of direct intersystem crossing from S2 to triplet manifold upon substitution with heavier chalcogen elements. The excited-state relaxation dynamics of sulfur/selenium substituted guanines in a vacuum is investigated using a combination of static quantum chemical calculations and on-the-fly excited-state molecular dynamics simulations. We find that in sulfur-substitution the S2 state predominantly decays to the S1 state, while upon selenium-substitution the S2 state deactivation leads to simultaneous population of the S1 and T2,3 states in the same time scale and multi-state quasi-degeneracy region S2/S1/T2,3. Interestingly, the ultrafast deactivation of the spectroscopic S3 state of both studied molecules to the S1 state occurs through a successive S3 → S2 → S1 path involving a multi-state quasi-degeneracy S3/S2/S1. The populated S1 and T2 states will cross the lowest triplet state, and the S1 → T intersystem crossing happens in a multi-state quasi-degeneracy region S1/T2,3/T1 and is accelerated by selenium-substitution. The present study reveals the influence of both the chalcogen substitution element and initial spectroscopic state on the excited-state relaxation mechanism of nucleobase photosensitizers and also highlights the important role of multi-state quasi-degeneracy in mediating the complex relaxation process. These theoretical results provide additional insights into the intrinsic photophysics of nucleobase-based photosensitizers and are helpful for designing novel photo-sensitizers for real applications.

Dielectric behaviour of nitrogen doped perovskite SrTiO3−δNδ films

Substitution of oxygen with nitrogen lowers crystal symmetry and modifies lattice vibrations in SrTiO3. The dielectric permittivity decreases through these intrinsic transformations and it increases due to dipolar relaxation of nitrogen-induced nanoregions.

Changing the reaction pathway in TiO2 photocatalytic dehalogenation of halogenated aromatic pollutants by surface hydroxyl regulation.

Understanding the photocatalytic reductive dehalogenation mechanism of halogenated aromatic pollutants is of great research value. However, the proton source in the photocatalytic dehalogenation process of representative halogenated aromatic pollutants by TiO2 is not clear. In this study, the TiO2 surface was modified by hydrochloric acid, sodium hydroxide, and sodium fluoride to obtain TiO2 samples with different hydroxyl groups. It was found that the hydroxyl groups on the surface of TiO2 affects the sequence of proton and electron transfer in dehalogenation. The abundance of hydroxyl groups on the surface of TiO2 can accelerate the reductive dehalogenation process of representative halogenated aromatic pollutants. The kinetic solvent isotope effect was used to study the proton-coupled electron transfer process in the reaction. It shows that the enriching of protons on TiO2 bridging oxygen (bridging hydroxyl groups) is conducive to the rapid step of protonation of the reactant, and subsequent proton and electron transfer. On the contrary, the bridging hydroxyl groups can be removed by reacting with strongly basic sodium hydroxide and sodium ions can occupy the bridging oxygen. The substitution of bridging oxygen by fluorine ions can also lead to the destruction of bridge hydroxyl groups. Significantly, the absence of bridging hydroxyl groups on titanium dioxide will lead to the dehalogenation of representative halogenated aromatic pollutants initiated by electron transfer. This study is helpful to understand dehalogenation reaction paths catalyzed by TiO2.

Origin of p-type conductivity in a WSe2 monolayer.

Transition-metal dichalcogenides have promising potentials for high-performance electronic and optoelectronic applications, which could be deeply influenced by defects, including native defects and dopants. Experiments to date have frequently reported p-type conductivity in the WSe2 monolayer, but the origin remains elusive. Here, using the first-principles calculations, we systematically investigate the point defects in the WSe2 monolayer and show that: (1) no intrinsic point defect is responsible for the p-type doping; (2) hydrogen interstitials (Hi) are possible sources for n-type conductivity; (3) oxygen substitution of Se (OSe) can greatly promote the formation of adjacent W vacancy (VW), and finally make VW relatively shallow acceptors by forming the defect complex nOSe + VW (n = 1 to 6). Our work reveals that nOSe + VW is the origin of the p-type conductivity in the unintentionally doped WSe2 monolayer, given that O is present throughout the synthesis conditions of WSe2.

Crystal Structure and Bond-Valence Investigation of Nitrogen-Stabilized LiAl5O8 Spinels.

An in-depth insight into the effect of nitrogen substitution on structural stabilization is important for the design of new spinel-type oxynitride materials with tailored properties. In this work, the crystal structures of ordered and disordered LiAl5O8 obtained by slow cooling and rapid quenching, respectively, were analyzed by a X-ray diffraction (XRD) Rietveld refinement and OccQP program. The variation in the bonding state of atoms in the two compounds was explored by the bond valence model, which revealed that the instability of spinel-type LiAl5O8 crystal structure at room temperature is mainly due to the severe under-bonding of the tetrahedrally coordinated Al cations. With the partial substitution of oxygen with nitrogen in LiAl5O8, a series of the nitrogen-stabilized spinel LiyAl(16+x-y)/3O8-xNx (0 < x < 0.5, 0 < y < 1) was successfully prepared. The crystal structures were systematically investigated by the powder XRD structural refinement combined with 7Li and 27Al magic-angle spinning nuclear magnetic resonance. All the Li+ ions entered the octahedra, while the Al resonances may be composed of multiple non-equivalent Al sites. The structural stability of spinel LiyAl(16+x-y)/3O8-xNx at ambient temperature was attributed to the cationic vacancies and high valence generated by the N ions, which alleviated the under-bonding state of the tetrahedral Al-O bond. This work provides a new perspective for understanding the composition-structure relationship in spinel compounds with multiple disorders.

The coral-like carbon nitride array: Rational design for efficient photodegradation of tetracycline under visible light

Carbon nitride photoactivity is limited by poor light utilization, rapid recombination of electron-hole (e--h+) pairs, and sluggish surface/interface reaction. Surface/interface modification is a promising strategy to get rid of these restrictions. Therefore, understanding surface/interface properties is highly worth in-depth consideration to improve carbon nitride photoactivity. Herein, the nitrogen-vacancy (Nv) and oxygen substitution (Os) co-modified carbon nitride coral-like array were rationally designed by a combination of thermal calcination and hydrothermal process. Results verified Nv extended the adsorption edge toward visible light and hampered the recombination of e--h+ pairs and Os accelerated surface/interface kinetics. In consequence, the optimized photocatalyst (Nv, Os)-CN-6 can degrade 80 % of tetracycline (TC) with the pseudo-first-order kinetic constant of 0.124 min−1, 13.8-fold higher than pristine carbon nitride. Furthermore, Nv and Os can well resist the toxic effect of interfering agents in simulated practical wastewater. Finally, Nv and Os endow (Nv, Os)-CN-6 mineralizing TC with low/non-ecology-risk intermediates evolution based on the HPLC-MS and T.E.S.T. software simulation. This study provides new insights into the rational design of carbon nitride for photodegrading TC.

Opto-electronic properties of carbon doped NiO

Hybrid functional first principles calculations reveal the effects of substitutional carbon on electronic and optical properties in the anti-ferromagnetic configuration of NiO. Spin polarized projected density of states and unfolded band structures show electronic band edge modification and magnetic anisotropy due to carbon substituting both at nickel and oxygen sites; only carbon substituted at an oxygen site, however results in the emergence of inter-band gap impurity states. This is due in part to the steric differences between carbon substituting nickel vs oxygen as well as the difference in valence between carbon and oxygen. Carbon substituting nickel is more stable than substituting oxygen, with a lower formation energy both in O-rich and O-poor conditions. Charge density isosurface plots reveal that carbon substituting nickel does not result in any appreciable modification to the bonding profile around the substitution, while oxygen substitution results in the formation of covalent bonds between the carbon and the nearest nickel atoms. Substitutional carbon at either the nickel or oxygen site causes a red shift in all optical properties towards the visible light region. The anisotropy in the optical and electronic properties for both carbon substitution at nickel and oxygen sites implies that these properties may be tuned through carbon doping and oxygen growth control for transparent conducting oxide and optoelectronic device applications.

Organic Phosphorescence Lasing Based on a Thermally Activated Delayed Fluorescence Emitter.

Organic phosphorescence materials provide an opportunity to use triplets for lasing. However, population inversion based on phosphorescence is hard to establish, owing to low luminescent quantum efficiency and intensive optical loss. By comparison, thermally activated delayed fluorescence emitters exhibit excellent optical gain with the aid of the reverse intersystem crossing (RISC) process. In this work, we designed a multifunctional gain material, not only serving as a thermally activated delayed fluorescence (TADF) emitter with excellent optical gain but also working as a phosphorescence source with high utilization of triplets. The lone pair of electrons in oxygen substitutions promotes a fast spin-flip and high delayed fluorescence quantum yield (ΦDF = 55%), enabling TADF amplified spontaneous emissions (ASE) of CH2Cl2 solution. Single-crystalline nanowires of H-aggregates effectively lower triplet energy levels with high phosphorescence quantum yield (ΦP = 27%), demonstrating Fabry-Perot mode phosphorescence lasing at 630 nm.

Controllable oxygen-doping of two-dimensional heterostructure as diode-type gas sensor with high performance

To meet the low energy consumption requirement of the Internet of things, there is an eagerness for 2D gas sensors to realize the ultralow-power or self-powered sensing at room temperature. Here, we demonstrate the controllable Oxygen-doping of SnS2/G heterostructure as a diode-type gas sensor with excellent and robust performances. The oxygen substitution controlled by ion irradiation modifies the homogeneous SnS2/G heterostructure into a heterogeneous SnS2-0.22O0.22/G-SnS2/G. The boundary of SnS2-0.22O0.22/G-SnS2/G forms a lateral Schottky junction, which outputs a stable open-circuit voltage of 1.5 V under the indoor light illumination. Adsorbed with gas molecules, the SnS2-0.22O0.22/G-SnS2/G junction has the variation of the photoconductance instead of the build-in electric field, ensuring the linear response to the gas concentration. This diode-type gas sensor exhibits long-term stability for at least 50 days (50th−100th day) and has an ultrafast gas-sensing performance with a response/recovery time of ∼54 s/9.2 s. Besides, it exhibits high selectivity to NO2 (42.8%) compared to gas species of H2S (0.6%), SO2 (7.8%), and NH3 (0%), based on different sensitivities. This work presents controllable oxygen doping as a novel avenue for preparing extremely energy-efficient sensors with fast response/recovery, linear response, and robust performances catering to future ubiquitous and real-time sensing requirements.