Effect Of Non-metal Doping Research Articles

Effect of non-metal doping on the optoelectronic properties of ZrS2/ZrSe2 heterostructure under strain: a first-principles study.

In this paper, we systematically studied the effects of non-metallic element (B, C, N, O, F) doping and biaxial stretching on the photoelectric properties of ZrS2/ZrSe2 heterostructures by using the first-principles calculation method based on density functional theory. The results show that the p-type doping is realized by B, C, and N atom doping, and the n-type doping is realized by O and F atom doping. The doping of B and C atoms produces impurity energy levels in the band gap, which affects the conductivity of the heterostructure. The band gap of N and O atom-doped heterostructures increases under tensile strain, but it is still a direct band gap. The analysis of the optical properties of the heterostructures shows that the doping of non-metallic atoms can adjust the optical absorption rate and reflectivity of the heterostructures. Under the action of tensile strain, the optical properties of the doped heterostructures have changed significantly in the low-energy region. This article provides a theoretical basis for the future application of ZrS2/ZrSe2 heterostructures. This paper uses the first-principles calculation method based on density functional theory. The PBE exchange-correlation functional based on generalized gradient approximation (GGA) is selected for the specific calculation, and the crystal structure is geometrically optimized by the ultrasoft pseudopotential method. It is verified that when the cutoff energy of the ZrS2/ZrSe2 heterostructure is 500 eV, the K-point grid is selected to be 10 × 10 × 2 with the lowest energy, so the cutoff energy is selected to be 500 eV. The K-point grid is selected to be 10 × 10 × 2. The convergence limits for structural optimization are as follows: the maximum force between atoms is 0.01 eV/Å, the convergence threshold of the maximum energy change is set to 10-9 eV/atom, and the convergence threshold of the maximum displacement is 0.001 Å. In order to avoid the influence of atomic periodic motion between different atomic layers, a vacuum layer of 20 Å is added in the vertical direction. Considering the interaction of vdW between the interfaces, the DFT-D2 method is used to verify. The optical properties were calculated by the random phase approximation method, and the K-point grid was selected as 12 × 12 × 2.

Effect of Non-Metal Doping on the Optoelectronic Properties of Monolayer 1T-CrS2 under Tensile Strain: A First-Principles Study

Effect of Non-Metal Doping on the Optoelectronic Properties of Monolayer 1T-CrS2 under Tensile Strain: A First-Principles Study

Effect of NM (B, C, N, O and F) doping and Fe[sbnd]NM co-doping on structure, electronic and magnetic properties of monolayer 2H[sbnd]MoTe[formula omitted] : A first principle investigation

Exploring magnetism in two-dimensional transition-metal dichalcogenides (TMDs) has gained a plethora of interest in recent times. Herein, employing spin-polarized density functional theory, we looked into the effect of non-metal doping (B, C, N, O, and F) and Fe-non metal co-doping on structure, electronic, and magnetic properties of 2HMoTe2 to identify new promising configurations for spin-based device applications. For non-metal doping, the results depict that B, N, and F-doped systems are magnetic, and the N-doped system shows magnetic-semiconducting behavior. The half-metallic Fe-doped MoTe2 transforms into a magnetic semiconductor upon co-doping. The structural distortion around the Fe atoms modifies the crystal field splitting, resulting in triply degenerate a1 and singly degenerate a2 and a3 states. Uncompensated electrons in the co-doped system and hybridization between Fe and NM atom modifies the magnetic properties of monolayer MoTe2. Competition between crystal field splitting and intra-atomic Hund’s exchange splitting determines the magnetic moment. Due to charge compensation, C-doped and FeC co-doped systems are non-magnetic. N-doped and FeN co-doped MoTe2 exhibit long-range magnetic ordering. Formation energy calculations revealed that the co-doped configurations are easily attainable in experiments compared to non-metal doped systems. The results open up a robust way to realize 2HMoTe2 based spintronic devices.

Effect of Non-Metal Doping on the Optoelectronic Properties of Monolayer 1T-HfS2 under Strain: A First-Principles Study

Effect of Non-Metal Doping on the Optoelectronic Properties of Monolayer 1T-HfS2 under Strain: A First-Principles Study

A first-principles study: single-layer TiS2 modified by non-metal doping.

In this paper, the effect of substitutional doping of boron (B), carbon (C), nitrogen (N), oxygen (O), and phosphorus (P) at the S-site on the electronic structure of the monolayer TiS2 system is investigated using a first-principles calculation method. The effect of nonmetal doping on the band gap of TiS2 and its mechanism were studied by analyzing the stability, electronic structure, and charge transfer of the system. By calculating the electron cloud overlap population and formation energy, we confirmed that the system is stable, and the Ti-X bond length of the doped system undergoes different degrees of distortion. The properties of the B, C, and N doped system show different properties with different doping concentrations; the band gap of the O-atom system gradually expands with the rise of the doping rate. The hybridization positions of the impurity and the intrinsic atoms are found by comparing the DOS; combined with the charge density difference, we confirmed the interaction of impurity atoms with the system and revealed the bonding process of different systems.

Transition metals decorated g-C3N4/N-doped carbon nanotube catalysts for water splitting: A review

• Synthesis of tubular g-C 3 N 4 based catalysts via various methods. • Construction of nanotubes with enhanced photo/electro-chemical water splitting. • The effect of non-metal doping on the catalytic performances of the nanotubes. • The effect of transition metals modification on the catalytic performances of the nanotubes. • Recent development in construction of g-C 3 N 4 based nanotube heterostructures and applications. As a metal-free and visible-light-responsive photocatalyst, graphitic carbon nitride (g-C 3 N 4 ) has been attracting considerable attention recent years due to its outstanding photocatalytic activity, low cost, appealing electronic band structure, high physicochemical stability, earth-abundant nature, and wide applications. The photocatalytic efficiency of g-C 3 N 4 and g-C 3 N 4 -based materials involving H 2 generation from H 2 O splitting depends on the separation and transport efficiency of the photogenerated charge carriers. Transition metal modification on g-C 3 N 4 / N -doped carbon nanotube-based catalysts offer the possibility of enhancing photo-/electro-catalytic performances of the materials. This review summarizes a panorama of the recent advances in development of g-C 3 N 4 / N -doped carbon nanotube based catalysts including (1) synthesis of tubular g-C 3 N 4 based catalysts via various methods, e. g., templating method and non-metal and transition metal doping; (2) construction of nanotubes with enhanced photo/electro-chemical water splitting efficiency and investigation of the effects of non-metal doping on the substrates; (3) the effect of transition metals (e.g., transition metal single atom and metal alloy) modification on the catalytic performances of the nanotubes; (4) recent development in construction of g-C 3 N 4 / N -doped carbon nanotube based heterostructures and the photocatalytic applications of the composite materials. The review attempts to cover the latest advances in development of next-generation g-C 3 N 4 -based nanotube catalysts.

Effect of non-metal doping on the photocatalytic activity of titanium dioxide on the photodegradation of aqueous bisphenol A

ABSTRACT Non-metals B, N, P and I were doped into titanium dioxide (TiO2) to form photocatalyst particles. TiO2 doped with various ratios of B, N, P and I were thus formed and these photocatalyst particles were bonded to fix each other in a column system under sunlight as a result of the photocatalytic degradation of bisphenol A (BPA). The doped TiO2 was characterized by X-ray diffraction (XRD), UV-visible absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS) to elucidate the mechanism of doping reaction. Doping with B, N, P and I to form the photocatalyst greatly red-shifted the absorption wavelength, increasing the effectiveness of the photocatalyst in reducing BPA. XPS analysis following doping revealed the bonding of B, N, P, I and other functional groups of the surface of the photocatalyst. Results of an experiment that involved the photocatalysts revealed that BPA degradations of 88%, 94%, 93% and 100% in 66.5 min under sunlight using B, N, P, and I-doped titanium dioxide, respectively. The doped photocatalysts were all superior to the undoped titanium dioxide.

Non-metal modified TiO2: a step towards visible light photocatalysis

Advanced oxidation process (AOP) is a versatile photocatalytic approach to degrade various environmental pollutants. Among many photocatalysts used in AOP such as ZnO, TiO2, ZrO2, ZnS, CdS; TiO2 is the most widely adopted semiconductor material. TiO2 is a wide band gap material and absorb in UV spectrum which is a narrow region in the sun light. This benchmark makes it a less efficient photocatalyst under sunlight irradiation. To enhance the photocatalytic efficiency, the absorption band of photocatalyst should be modified in such a way that it leads to maximum absorption in the solar spectrum. The doping of nonmetals such as N, C, P and S etc. shift the band edge of the semiconductors towards the visible region and thus increases the photon absorption which successively enhances the photocatalytic efficiency. In this review, we have focused on effect of nonmetal doping on the properties and photocatalytic activity of the TiO2. Influence of various aspects such as synthesis procedure, doping source, concentration of dopant, calcination etc. are also explored towards alteration in properties and photocatalytic efficiency of nonmetals doped TiO2.

Insight into phosphate doped BiVO4 heterostructure for multifunctional photocatalytic performances: A combined experimental and DFT study

Doping with non-metals like phosphorous has been extensively investigated to extend radiation absorption and improve the photocatalytic efficiency of TiO2. However, the effect of non-metal doping in BiVO4, whose smaller bandgap (2.4 eV) allows for efficient visible light absorption, has been scarcely investigated. Visible light accounts for 45% of solar energy (as compared to only 5% of UV light) reaching the Earth’s surface. Due to its high efficiency in absorbing visible radiation, BiVO4 can, therefore, be a promising material to replace TiO2. Here we demonstrate the synthesis of phosphate doped visible-light-active BiVO4 by a microwave hydrothermal method as a promising alternative to TiO2. Subsequently, we investigated its photocatalytic activity for the removal of p-amino salicylic acid and ibuprofen, two cases of major pharmaceutical waste, as well as disinfection of multi-drug resistance Staphylococcus aureus bacteria. In addition, the biofilm elimination efficiency of the undoped and phosphate doped BiVO4 was studied by crystal violet staining method. A 70% reduction in the biofilm biomass by phosphate doped BiVO4 was obtained. Also, a 4.1log reduction in the viable cells count was observed within 180 min when Staphylococcus aureus was irradiated with visible light mixed in phosphate doped BiVO4 powder. Under similar irradiation conditions, the degradation efficiency for p-amino salicylic acid and ibuprofen are 81% and 80% respectively, a 40% enhancement as compared to undoped BiVO4. First principle density functional theory calculations show that charge transfer from P to O in the doping site of the BiVO4 is responsible for the enhanced photocatalytic activity.

Effects of nonmetal doping on electronic structures of NaNbO3 based on hybrid density functional calculation

The influences of a series of anion doping on the electronic structures of sodium niobate (NaNbO3) have been systematically investigated by density functional theory (DFT) calculations with the hybrid B3LYP functional. As for B[Formula: see text](C,[Formula: see text]P)-doped NaNbO3, the isolated B 2p (C 2p, P 3p) states were formed above the valence band maximum (VBM) of NaNbO3, which were too weak to mix with O 2p states and thus produced band gap narrowing. While the band gap of NaNbO3 was slightly narrowed after F doping. As for S-doped NaNbO3, the S 3p states mixed with O 2p states well and thus reduced the band gap energy. According to the calculation results, we tentatively put forward that S doping would be appropriate for single anion doping NaNbO3, while the B[Formula: see text](C,[Formula: see text]P) elements would be suitable candidates for co-doping NaNbO3.

Effects of Nonmetal Doping on Electronic Structures and Optical Property of Anatase TiO2 from First-Principles Calculations

Abstract The crystal structures, electronic structures and optical properties of pure and nonmetal (B, C, N, F, P, S and Cl) doping anatase TiO 2 were calculated by the first-principles based on the density functional theory with the plane-wave ultrasoft pesudopotentials method. The calculated results show that the octahedral dipole moments of TiO 2 are increased by nonmetal doping owing to the changes of lattice parameters, bond length and charges on atoms, which is very effective for the separation of photoexcited electron-hole pairs. Because the impurity energy levels are formed by hybridizing with dopants' p states, O 2p states and Ti 3d states, most dopants could narrow the band gap, resulting in its fundamental absorption edge red-shift to visible-light region. According to the calculated results, the effects of nonmetal doping on electronic structure and optical properties of anatase TiO 2 were analyzed and compared, and the roles of nonmetal atoms in TiO 2 photocatalyst under visible-light irradiation were clarified. The calculated results could explain the reasons that some nonmetal-doped TiO 2 have higher photocatalytic activity under visible-light irradiation.