g-C3N4纳米带的电子结构及光学性质的第一性原理计算

采用密度泛函理论的第一性原理方法研究了扶手椅型g-C₃N₄纳米带（AC-g-C₃N₄NRs）和锯齿型g-C₃N₄纳米带（ZZ-g-C₃N₄NRs）的电子结构和光学性质。结果表明：AC-g-C₃N₄NRs和ZZ-g-C₃N₄NRs的边缘H原子均能稳定存在。AC-g-C₃N₄NRs的价带顶主要由多数N原子贡献,而ZZ-g-C₃N₄NRs的价带顶主要由CH边缘附近的N原子贡献。AC-g-C₃N₄NRs的导带底主要属于纳米带一侧边缘或两侧边缘附近的C原子和N原子,而ZZ-g-C₃N₄NRs导带底主要属于ZZ-g-C₃N₄NRs的NH边缘附近的C原子和N原子。AC-g-C₃N₄NRs和ZZ-g-C₃N₄NRs的吸收系数和反射率都随纳米带宽度的增加而增加。随着AC-g-C₃N₄NR宽度的增加,吸收系数在低能区域产生明显的蓝移现象。     

Structure and Stability of Isomers of the Promising Interstellar Molecule PC3O

DFT/B3LYP/6-311G(d) and CCSD(T)/6-311G(2d) single-point calculations are carried out for exploring the doublet potential energy surface (PES) of PC₃O, a molecule of potential interest in interstellar chemistry. A total of 29 minima connected by 65 interconversion transition states are located. The structures of the most relevant isomers and transition states are further optimized at the QCISD level followed by CCSD(T) single-point energy calculations. At the CCSD(T)/6-311G(2df)//QCISD/6-311G(d)+ZPVE level, the global minimum is the quasi-linear structure PCCCO 1 (0.0 kcal/mol) with a great kinetic stability of 47.9 kcal/mol, and the cumulenic form features largely in its resonance structures. Moreover, the chainlike isomer OPCCC 3 (64.5) and five-membered-ring species cPCCCO 19 (77.8) possess considerable kinetic stability of about 18.0 kcal/mol. All these three isomers are very promising candidates for future experimental and astrophysical detection. Additionally, a three-membered-ring isomer CC-cCOP 10 (69.6) has slightly lower kinetic stability of around 15 kcal/mol and may also be experimentally observable. Possible formation mechanisms of the four stable isomers in interstellar space are discussed. The present research is the first attempt to study the isomerization and dissociation mechanisms of PC _n O series. The predicted spectroscopic properties, including harmonic vibrational frequencies, dipole moments and rotational constants for the relevant isomers, are expected to be informative for the identification of PC₃O in laboratory and interstellar medium.     

Cr、Sn、Co掺杂对层状二维材料MoSi2N4的电子和光学性能的影响(英文)

基于新合成的二维材料MoSi₂N₄(MSN),我们建立了一系列MSN的掺杂模型进行了第一原理计算。首先,我们计算了本征MSN的电子特性,包括其能带结构和态密度。然后我们研究了Cr、Sn和Co掺杂对MSN的电子和光学性质的影响。结果表明,在3种掺杂体系中,Co掺杂体系表现出最低的形成能,这表明Co掺杂体系是最稳定的。通过带隙计算表明,尽管3种掺杂模型都降低了MSN的固有带隙,但却表现出3种不同的电子特性。态密度图也显示,Cr和Co掺杂体系都在导带底(CBM)和价带顶(VBM)附近产生局部尖峰。此外,光学性质的计算中表明,掺杂后体系的光学性质也得到了改善。     

Cu2O(SO4), dolerophanite: Refinement of the crystal structure,with a comparison of [O Cu(II)4] tetrahedra in inorganic compounds

The refinement of the crystal structure of Cu₂O(SO₄), dolerophanite, [a=9.370 (1) Å,b=6.319 (1) Å,c=7.639 (1) Å, =122.34 (1)°; space group C 2/m;Z=4;R=0.035] confirmed the trigonal dipyramidal coordination of one Cu(II) atom (mean distance Cu-O=2.025 Å). One O atom is tetrahedrally surrounded by four Cu(II) atoms; the mean Cu(II)-O distance of 1.918 Å compares well to [O Cu(II)₄] tetrahedra found in inorganic crystal structures.de|Die Verfeinerung der Kristallstruktur von Cu₂O(SO₄), Dolerophanit, [a=9.370 (1) Å,b=6.319 (1) Å,c=7.639 (1) Å, =122.34 (1)°; Raumgruppe C 2/m;Z=4;R=0.035] bestätigte die trigonal dipyramidale Koordination des einen Cu(II)-Atoms (mittlerer Cu-O-Abstand=2.025 Å). Ein O-Atom ist tetraedrisch von vier Cu(II)-Atomen umgeben; der mittlere Cu(II)-O-Abstand von 1.918 Å entspricht den in ähnlichen [O Cu(II)₄]-Tetraedern von anorganischen Kristallstrukturen gefundenen Werten.

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Cu₂O(SO₄), Dolerophanit: Verfeinerung der Kristallstruktur mit einem Vergleich von [O Cu(II)₄]-Tetraedern in anorganischen Verbindungen

     

The effect of calcination conditions on the superconducting properties of Y−Ba−Cu−O powders

Calcination conditions of the precursor powders, i.e. temperature, type of atmosphere and duration, were determined with a view to obtain superconducting powders with the most advantageous physico-chemical properties. Investigated were powders in the Y?Ba?Cu?O system prepared by the sol-gel method. Thermogravimetric examinations of the powders have revealed that the decomposition kinetics of BaCO₃ determines the formation rate of the superconducting YBa₂Cu₃O_7?x (‘123’) phase. It follows from the decomposition kinetics of BaCO₃ that the process is the most intensive in argon, whereas in static air and oxygen it is the slowest. The phase composition analysis (XRD) and low-temperature magnetic susceptibility measurements of the calcinated powders, confirm the above mentioned changes in the decomposition kinetics. The reaction of barium carbonate can be completed if the calcination process is conducted at the temperature of 850°C for 25 h, yielding easily sinterable powders for obtaining single-phase superconducting bulk samples with advantageous functional parameters.     

Effect of Cr and Mn ions on the structure and magnetic properties of GaFeO3: Role of the substitution site

Effect of substitution of Cr and Mn in the Fe and Ga sites of GaFeO₃ on the structural parameters and magnetic properties has been investigated by preparing GaFe_1−xCr_x(Mn_x)O₃ and Ga_1−xCr_x(Mn_x)FeO₃ starting with appropriate oxide precursors. It is shown that, starting with Cr or Mn substituted Ga₂O₃, one obtains Ga_1−xCr_x(Mn_x)FeO₃, while reaction of Cr or Mn substituted α-Fe₂O₃ with Ga₂O₃ yields GaFe_1−xCr_x(Mn_x)O₃. The structural parameters and magnetic properties vary significantly with the substitution site of Cr showing a large decrease in the unit cell parameters as well as the T_C and other magnetic properties when the substitution is at the octahedral Fe (1, 2) site. Substitution of Cr at the octahedral Ga2 site results in marginal changes. Substitution of Mn in the Ga and Fe sites also show differences although the changes themselves are much smaller. First-principles calculations confirm such site-specificity and show how Cr substitution affects the properties differently when substituted at the Ga2 and Fe1 sites.     

A Density Functional Theory and Microkinetic Study of Acetylene Partial Oxidation on the Perfect and Defective Cu2O (111) Surface Models

The catalytic removal of C₂H₂ by Cu₂O was studied by investigating the adsorption and partial oxidation mechanism of C₂H₂ on both perfect (stoichiometric) and Cu_CUS-defective Cu₂O (111) surface models using density functional theory calculations. The chemisorption of C₂H₂ on perfect and defective surface models needs to overcome the energy barrier of 0.70 and 0.81 eV at 0 K. The direct decomposition of C₂H₂ on both surface models is energy demanding with the energy barrier of 1.92 and 1.62 eV for the perfect and defective surface models, respectively. The H-abstractions of the chemisorbed C₂H₂ by a series of radicals including H, OH, HO₂, CH₃, O, and O₂ following the Langmuir–Hinshelwood mechanism have been compared. On the perfect Cu₂O (111) surface model, the activity order of the adsorbed radicals toward H-abstraction of C₂H₂ is: OH > O₂ > HO₂ > O > CH₃ > H, while on the defective Cu₂O (111) surface model, the activity follows the sequence: O > OH > O₂ > HO₂ > H > CH₃. The Cu_CUS defect could remarkably facilitate the H-abstraction of C₂H₂ by O₂. The partial oxidation of C₂H₂ on the Cu₂O (111) surface model tends to proceed with the chemisorption process and the following H-abstraction process rather than the direct decomposition process. The reaction of C₂H₂ H-abstraction by O₂ dictates the C₂H₂ overall reaction rate on the perfect Cu₂O (111) surface model and the chemisorption of C₂H₂ is the rate-determining step on the defective Cu₂O (111) surface model. The results of this work could benefit the understanding of the C₂H₂ reaction on the Cu₂O (111) surface and future heterogeneous modeling.     

Chirality and Relativistic Effects in Os3(CO)12

The energy and structural parameters were obtained for all forms of the carbonyl complex of osmium Os₃(CO)₁₂ with D_3h and D₃ symmetries using density functional theory (DFT) methods. The calculations took into account various levels of relativistic effects, including those associated with nonconservation of spatial parity. It was shown that the ground state of Os₃(CO)₁₂ corresponds to the D₃ symmetry and thus may be characterized either as left-twisted (D_3S) or right-twisted (D_3R). The D_3S↔D_3R transitions occur through the D_3h transition state with an activation barrier of ~10^–14 kJ/mol. Parity violation energy difference (PVED) between D_3S and D_3R states equals to ~5 × 10⁻¹⁰ kJ/mol. An unusual three-center exchange interaction was found inside the {Os₃} fragment. It was found that the cooperative effects of the mutual influence of osmium atoms suppress the chirality of the electron system in the cluster.     

Selective paramagnetic relaxation reagents (SPRR). Study of line broadening effect of Cu2+ ions on the13C-NMR spectral lines of N-containing molecules

Summary The selective line broadening effect of the paramagnetic Cu²⁺ on the¹³C-NMR linewidths of nitrogen compounds has been studied. It operates through electron-nuclear hyperfine coupling, however, chemical exchange processes also contribute significantly. The observed selective broadenings make possible the assignments of carbon atoms one or two bonds away from a basic nitrogen (earlier assignment of quinidine has been modified), the determination of likely metal binding sites of a complex and the relative basicity of different nitrogen atoms of the same molecule. The broadenings depend also on the spatial vicinity of the Cu²⁺ ion and the interacting nuclei. While its main advantage is simplicity, the main drawback is that it is limited to molecules capable to form complexes with Cu²⁺ ion.

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Selektive paramagnetische Relaxationsreagenzien (SPRR). Untersuchung des Linienverbreiterungs-effekts von Cu²⁺-Ionen auf die¹³C-NMR-Signale in N-Verbindungen

Zusammenfassung Es wurde der selektive Verbreiterungseffekt von paramagnetischen Cu²⁺-Ionen auf¹³C-NMR-Linienbreiten von Stickstoff-Verbindungen untersucht. Diese Verbreiterung erfolgt durch Elektron-Kern-Hyperfeinkopplung, allerdings liefern auch chemische Austauschprozesse signifikante Beiträge. Die beobachteten Verbreiterungen erlauben die Zuordnung von Kohlenstoffatomen, die eine oder zwei Bindungen vom basischen Stickstoffatom entfernt sind (die frühere Zuordnung für Chinidin mußte modifiziert werden). Außerdem können die Koordinationsstellen festgestellt und eine relative Basizitätszuordnung von verschiedenen Stickstoffatomen innerhalb eines Moleküls getroffen werden. Die Verbreiterungen hängen auch von der räumlichen Nachbarschaft der Cu²⁺-Ionen und dem in Wechselwirkung befindlichen Kern ab. Der Hauptvorteil ist die Einfachheit der Methode, der Hauptnachteil liegt in der Limitierung der Methode auf Moleküle, die mit Cu²⁺ Komplexe bilden können.

     

温度和电极互换频率对电解过程中聚合Al13形成的影响

聚合铝作为一种无机高分子絮凝剂,具有比传统絮凝剂如硫酸铝、氯化铁等效能优异,比有机高分子絮凝剂价格低廉等优点[1￣3]。研究表明,聚合铝絮凝剂实际上是在一定条件下控制铝的水解-聚合-沉淀过程的中间产物,其溶液除存在铝的单体及二聚体外,     

First Principle Calculation of the Geometrical and Electronic Structure of Impurity-Doped β-FeSi2 Semiconductors

The geometrical and electronic structures of impurity (Cr, Mn, Co, Ni)-doped β-FeSi₂ were investigated using first principles pseudopotential calculations based on generalized gradient approximation (GGA) density function theory. The calculated structural parameters depend strongly on the kinds of dopants and sites. The total energy calculations for substitution of dopants at the Fe_I and the Fe_II sites revealed that Mn prefers the Fe_I site, whereas Cr, Co, and Ni prefer the Fe_II site. The electronic structure is analyzed and discussed in terms of the atomic charges, bond overlap population, and total and partial densities of states (DOS).     

A First-Principles Study on the Adsorption of Small Molecules on Arsenene: Comparison of Oxidation Kinetics in Arsenene,Antimonene, Phosphorene,and InSe

Arsenene, a new group-V two-dimensional (2D) semiconducting material beyond phosphorene and antimonene, has recently gained an increasing attention owning to its various interesting properties which can be altered or intentionally functionalized by chemical reactions with various molecules. This work provides a systematic study on the interactions of arsenene with the small molecules, including H₂, NH₃, O₂, H₂O, NO, and NO₂. It is predicted that O₂, H₂O, NO, and NO₂ are strong acceptors, while NH₃ serves as a donor. Importantly, it is shown a negligible charge transfer between H₂ and arsenene which is ten times lower than that between H₂ and phosphorene and about thousand times lower than that between H₂ and InSe and antimonene. The calculated energy barrier for O₂ splitting on arsenene is found to be as low as 0.67 eV. Thus, pristine arsenene may easily oxidize in ambient conditions as other group V 2D materials. On the other hand, the acceptor role of H₂O on arsenene, similarly to the cases of antimonene and InSe, may help to prevent the proton transfer between H₂O and O− species by forming acids, which suppresses further structural degradation of arsenene. The structural decomposition of the 2D layers upon interaction with the environment may be avoided due to the acceptor role of H₂O molecules as the study predicts from the comparison of common group V 2D materials. However, the protection for arsenene is still required due to its strong interaction with other small environmental molecules. The present work renders the possible ways to protect arsenene from structure degradation and to modulate its electronic properties, which is useful for the material synthesis, storage and applications.     

On the crystal chemistry of three copper(II)-arsenates: Cu3(AsO4)2-III,Na4Cu(AsO4)2, and KCu4(AsO4)3

The three copper(II)-arsenates were synthesized under hydrothermal conditions; their crystal structures were determined by single-crystal X-ray diffraction methods:Cu₃(AsO₄)₂-III:a=5.046(2) Å,b=5.417(2) Å,c=6.354(2) Å, =70.61(2)°, =86.52(2)°, =68.43(2)°,Z=1, space group ,R=0.035 for 1674 reflections with sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a=4.882(2) Å,b=5.870(2) Å,c=6.958(3) Å, =98.51(2)°, =90.76(2)°, =105.97(2)°,Z=1, space group ,R=0.028 for 2157 reflections with sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a=12.234(5) Å,b=12.438(5) Å,c=7.307(3) Å, =118.17(2)°,Z=4, space group C2/c,R=0.029 for 1896 reflections with sin / 0.80 Å^–1.Within these three compounds the Cu atoms are square planar [4], tetragonal pyramidal [4+1], and tetragonal bipyramidal [4+2] coordinated by O atoms; an exception is the Cu(2)^[4+1] atom in Cu₃(AsO₄)₂-III: the coordination polyhedron is a representative for the transition from a tetragonal pyramid towards a trigonal bipyramid. In KCu₄(AsO₄)₃ the Cu(1)^[4]O₄ square and the As(1)O₄ tetrahedron share a common O—O edge of 2.428(5) Å, resulting in distortions of both the CuO₄ square and the AsO₄ tetrahedron. The two Na atoms in Na₄Cu(AsO₄)₂ are [6] coordinated, the K atom in KCu₄(AsO₄)₃ is [8] coordinated by O atoms.Die drei Kupfer(II)-Arsenate wurden unter Hydrothermalbedingungen gezüchtet und ihre Kristallstrukturen mittels Einkristall-Röntgenbeugungsmethoden ermittelt:Cu₃(AsO₄)₂-III:a = 5.046(2) Å,b = 5.417(2) Å,c = 6.354(2) Å, = 70.61 (2)°, = 86.52(2)°, = 68.43(2)°,Z = 1, Raumgruppe ,R = 0.035 für 1674 Reflexe mit sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a = 4.882(2) Å,b = 5.870(2) Å,c = 6.958(3) Å, = 98.51(2)°, = 90.76(2)°, = 105.97(2)°,Z = 1, Raumgruppe ,R = 0.028 für 2157 Reflexe mit sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a = 12.234(5) Å,b = 12.438(5) Å,c = 7.307(3) Å, = 118.17(2)°,Z = 4, Raumgruppe C2/c,R = 0.029 für 1896 Reflexe mit sin / 0.80 Å^–1.Die Cu-Atome in diesen drei Verbindungen sind durch O-Atome quadratisch planar [4], tetragonal pyramidal [4 + 1] und tetragonal dipyramidal [4 + 2]-koordiniert; eine Ausnahme ist das Cu(2)^{[4 + 1]}-Atom in Cu₃(AsO₄)₂-III: Das Koordinationspolyeder stellt einen Vertreter des Übergangs von einer tetragonalen Pyramide zu einer trigonalen Dipyramide dar. In KCu₄(AsO₄)₃ haben das Cu(1)^[4]O₄-Quadrat und das As(1)O₄-Tetraeder eine gemeinsame O—O-Kante von 2.428(5) Å, was eine Verzerrung der beiden Koordinationsfiguren CuO₄-Quadrat und AsO₄-Tetraeder bedingt. Die zwei Na-Atome in Na₄Cu(AsO₄)₃ sind durch O-Atome [6]-koordiniert, das K-Atom in KCu₄(AsO₄)₃ ist [8]-koordiniert.

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Zur Kristallchemie dreier Kupfer (II)-Arsenate: Cu₃(AsO₄)₂-III, Na₄Cu(AsO₄)₂ und KCu₄(AsO₄)₃

     

The importance of valencep functions in the bonding of Na2, K2, and Cu2 and their positive and negative ions

Summary The relative importance of the valencep functions for describing the bonding in the valence isoelectronic Na₂, K₂, and Cu₂ molecules and their positive and negative ions is investigated. In absolute magnitude the contribution of thep functions to the dissociation energy follows the trend Cu>Na>K while by percentage of the dissociation energy the importance of thep functions follows the polarizabilities, i.e. K>Na>Cu. The bonding in K₂, K ₂ ⁺ , and K ₂ ^– is analyzed to explain the observed trends.Dedicated to Prof. Klaus Ruedenberg     

Effect of substituents in the ring on the structure and electron density distribution in benzyl halides

The results of calculations for benzyl chlorides and benzyl bromides that contain substituents in the ring by different quantum-chemical methods are compared. The electron density on the benzyl carbon atom increases as the electron-withdrawing properties of substituents are enhanced due to the shift of the electron density from the benzyl halogen atom to the adjacent carbon atom. A topological analysis according to Bader confirmed the main reason for the change in the paramagnetic shielding of the benzyl¹³C nuclei. The results of calculations provide, for the first time, an explanation for the resonance upfield¹³C shift of this atom as the Hammett constant of a substituent increases in compounds of the series under consideration. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2111–2119, December, 1997.     

Subsolidus phase relations and crystal structure of compounds in the PrOx-CaO-CuO system

The subsolidus phase relations of the PrO_x-CaO-CuO pseudo-ternary system sintered at 950-1000°C have been investigated by X-ray powder diffraction. In this system, there exist one compound Ca₁₀Pr₄Cu₂₄O₄₁, one Ca₂Pr₂Cu₅O₁₀-based solid solution, seven three-phase regions and two two-phase regions. The crystal structures of Ca₁₀Pr₄Cu₂₄O₄₁ and Ca₂Pr₂Cu₅O₁₀-based solid solution have been determined. Compound Ca₁₀Pr₄Cu₂₄O₄₁ crystallizes in an orthorhombic cell with space group D_2h²⁰−Cccm, Z=4. Its lattice parameters are a=11.278(2) Å, b=12.448(3) Å and c=27.486(8) Å. The crystal structure of Ca₂Pr₂Cu₅O₁₀-based solid solution is an incommensurate phase based on the orthorhombic NaCuO₂ type subcell. The lattice parameters of the subcell of the Ca_2.4Pr_1.6Cu₅O₁₀ are a₀=2.8246(7) Å, b₀=6.3693(5) Å, c₀=10.679(1) Å, and those of the orthorhombic superstructure are with a=5a₀, b=b₀, c=5c₀. The Ca_2.4Pr_1.6Cu₅O₁₀ structure can also be determined by using a monoclinic supercell with space group C_2h⁵−P2₁/c, Z=4, a=5a₀, b=b₀, and β=104.79(1)° or 136.60(1)°, V=5a₀b₀c₀.     

Isotope Effects on Chemical Shifts in the Study of Hydrogen Bonds in Small Molecules

This review is giving a short introduction to the techniques used to investigate isotope effects on NMR chemical shifts. The review is discussing how isotope effects on chemical shifts can be used to elucidate the importance of either intra- or intermolecular hydrogen bonding in ionic liquids, of ammonium ions in a confined space, how isotope effects can help define dimers, trimers, etc., how isotope effects can lead to structural parameters such as distances and give information about ion pairing. Tautomerism is by advantage investigated by isotope effects on chemical shifts both in symmetric and asymmetric systems. The relationship between hydrogen bond energies and two-bond deuterium isotope effects on chemical shifts is described. Finally, theoretical calculations to obtain isotope effects on chemical shifts are looked into.     

The structure of 1-formyl-3-phenyl-Δ-pyrazoline in the gas phase (DFT calculations), in solution (NMR) and in the solid state (X-ray crystallography)

The molecular structure of 1-formyl-3-phenyl-Δ²-pyrazoline was determined by X-ray crystallography (triclinic, P-1). The geometry thus obtained was compared with that obtained by DFT calculations. The GIAO method was used to calculate absolute shieldings, which agree conveniently with those measured by ¹³C and ¹⁵N NMR. The title compound appears to be an essentially planar molecule.     

Quantum Chemical Calculations on the Structure and Adsorption Properties of NO and N2O on Ag+ and Cu+ Ion-Exchanged Zeolites

Ab initio cluster quantum chemical calculations at the Hartree–Fock (HF/Lanl2dz) and correlated second-order Moller–Plesset perturbation theory (MP2/Lanl2dz) levels were performed for NO and N₂O interactions with Ag⁺ and Cu⁺ ion-exchanged zeolites. The interaction energies were estimated in a conventional way and also corrected for basis set superposition errors. It was shown that the highly dispersed Ag⁺ counterions establish twofold coordination to the lattice oxygens on the zeolite surface, similar to the case of Cu⁺ ions. However, both NO and N₂O bind relatively strongly to the Cu active sites of Cu⁺ ion-exchanged zeolites than those of the Ag⁺ site of the Ag⁺ ion-exchanged zeolites. Based on the results of these calculations, the two different forms of adsorption for these molecules on the catalyst surface, the nature of their binding and characteristics of the adsorption properties have been discussed. Finally, some comparisons with the results obtained by a variety of density functional theory calculations on target systems have been presented.     

Synergistic Effects of B-F/B-S and Nitrogen Vacancy Co-Doping on g-C3N4 and Photocatalytic CO2 Reduction Mechanisms: A DFT Study

Nonmetallic co-doping and surface hole construction are simple and efficient strategies for improving the photocatalytic activity and regulating the electronic structure of g-C₃N₄. Here, the g-C₃N₄ catalysts with B-F or B-S co-doping combined with nitrogen vacancies (N_v) are designed. Compared to the pristine g-C₃N₄, the direction of the excited electron orbit for the B-F-co-doped system is more matching (N_2pz→C_2pz), facilitating the separation of electrons and holes. Simultaneously, the introduced nitrogen vacancy can further reduce the bandgap by generating impurity states, thus improving the utilization rate of visible light. The doped S atoms can also narrow the bandgap of the B-S-N_v-co-doped g-C₃N₄, which originates from the p-orbital hybridization between C, N, and S atoms, and the impurity states are generated by the introduction of N vacancies. The doping of B-F-N_v and B-S-N_v exhibits a better CO₂ reduction activity with a reduced barrier for the rate-determining step of around 0.2 eV compared to g-C₃N₄. By changing F to S, the origin of the rate-determining step varies from *CO₂→*COOH to *HCHO→*OCH₃, which eventually leads to different products of CH₃OH and CH₄, respectively.