Non-metallic Elements Research Articles

First-principles calculations to investigate electronic structures and magnetic regulation of non-metallic elements doped BP with point defects

In order to control the magnetic properties and electronic structures of black phosphorene (BP) monolayer, the structures, electronic and magnetic properties of non-metallic elements doped BP monolayer without or with defects including P vacancy (VP) have been studied by density functional theory (DFT). Defective BP appears ferromagnetic metallicity, and the magnetic moment is 0.086 μB. The magnetism mainly comes from the spin polarization of P atoms near the defect point. For non-metallic elements doped intrinsic BP, system doped with B and N shows P-type semiconductor. C doped shows non-magnetic metal properties. Odoped exhibits magnetic P-type semiconductor. Si and S doped shows ferromagnetic metal properties. The magnetism mainly comes from the spin polarization of P atoms near the defect point, and a small part comes from doped atoms. In the case of non-metallic elements doped defective BP, the results show that flaw-b-C and flaw-s-Si exhibit non-magnetic metallic properties. The flaw-b-S shows P-type semiconductor with indirect band gap of 0.712 eV. Other systems exhibit ferromagnetic metallicity, and the magnetism mainly comes from the spin polarization of P atoms near defect point. Non-metallic elements doped BP monolayer without or with point defects can effectively adjust magnetic properties and electronic structures.

Monoclonal antibody based immunoassay: An alternative way for aquatic environmental selenium detection

Environmental concerns about human health encouraged increasing methodological interest in selenium (Se), which is an essential non-metal trace element and varies within a narrow concentration range between essential and toxic. In this study, two types of long-armed Se haptens (Se-hapten-lc-NHS) were synthesized for the first time using active ester formalization. In producing monoclonal antibodies (mAbs), the derivatization of haptenized Se at para- (meta-) and ortho-sites showed different properties. Finally, a mAb derived from hybridoma 5A52 was confirmed to be capable of establishing an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). There was a successful quantitative determination of Se4+ with a detection range of 17 to 207 pmol mL−1 and a limit of detection of approximately 3.9 pmol mL−1. The mAb was found to be remarkably sensitive and specific, with no evidence of cross-reactivity with other ions. The assay was validated for four kinds of Se forms in water samples and showed satisfactory recoveries between 80 % and 108 %, with coefficients of variation of 2.1 %–11 %. The method proposed in our study offers a useful protocol for the rapid screening of Se and provides an alternative solution for the analysis of Se in aquatic environments.

Constructing boron-doped graphitic carbon nitride with 2D/1D porous hierarchical architecture and efficient N2 photofixation

Rational design of cheap and easily available semiconductor photocatalysts for photocatalytic nitrogen fixation has attracted widespread attention. However, the enhancing efficiency of fixation nitrogen into ammonia (NH3) under mild conditions is still a challenge. Based on the energy band engineering theory, the band gap of graphitic carbon nitride (g-C3N4) can be adjusted by boron element doping. In this study, boron-doped graphitic carbon nitride with a porous rod-like 2D/1D hierarchical architecture was prepared (BCN) via a convenient hydrothermal and thermal polymerization method. Due to its special structure, the as-prepared BCN photocatalysts had a high specific surface area, enhanced visible light absorption and good photogenerated carrier separation efficiency. The optimal ammonia yield of BCN can reach 434.74 μmol·g−1·h−1 without the presence of a sacrificial agent, which was 57.35 times higher than that of bulk g-C3N4. According to the analysis of the experimental results, the excellent photocatalytic nitrogen fixation performance was due to the synergistic effect between the doping of nonmetallic boron element and the 2D/1D porous structure, which exposed more active sites, thus boosting the photocatalytic nitrogen fixation efficiency. This study provides a guiding significance for the construction of high-efficiency photocatalysts with a special 2D/1D porous hierarchical architecture in photocatalytic nitrogen fixation.

Synthesis of enriched oxygen vacancy TiO2 microsphere with rapid response to isopropylamine and its application in herbicide detection

Real-time detection of herbicides has been a challenge for the application of metal oxide gas sensors. In this paper, we report the application of TiO2 sensors with oxygen vacancies for the detection of isopropylamine. Spherical structure with oxygen vacancies was successfully prepared by a simple one-step hydrothermal method combined with ionic liquid as morphology regulator. The morphology and structure of the materials were analyzed using XRD, SEM and TEM. Further studies reveal that the oxygen vacancies in this material play an important role in the detection of isopropylamine. The sensor exhibits excellent selectivity, moisture resistance and long-term stability. The response is 61.7–100 ppm isopropylamine, along with fast response time of 22 s. It is noteworthy that the lower limit of detection for isopropylamine can reach 0.2 ppm, which is very meaningful to practical application of detecting gas residues. The excellent performance can primarily be attributed to the formation of abundant oxygen vacancies into the material, which increases the adsorption capacity of gas molecules. This new sensing design strategy offers a vital reference to extend the application of non-metallic elements doped metal oxide semiconductors.

Computational screening of nonmetal dopants to active MoS2 basal-plane for hydrogen evolution reaction via structural descriptor

Nonmetal doping is an efficient approach to activate inert MoS2 basal plane, which converts MoS2 into an electrocatalyst for the hydrogen evolution reaction (HER). However, the trial-and-error approach through experimental attempt is still a common practice to search for suitable nonmetal dopants. In this work, we employ density functional theory (DFT) and microkinetic model to assess alkaline HER activity of nonmetal-modified MoS2(001), which show strong variation in the degree of activation by single- or double-dopants across nonmetal element series (B, C, N, P, O, S, Se and Te). To assist the screening of nonmetal dopants to active MoS2 basal plane, a structural descriptor-based prediction model is constructed. It demonstrates that the activation effect of nonmetal dopant is achieved through the adjustment of valence electron occupancy of reaction center, which tunes the adsorption energy of atomic hydrogen and hydroxide radical, and accordingly reaction kinetic for alkaline HER. The structural descriptor-based prediction model reproduce the activity trend among non-metallic doped MoS2 from available experimental references. In addition, we screened out MoS2 modified by BTe and BSe double dopants with lower overpotential than reported nonmetal-modified MoS2 systems. This work gives a deep insight into activation mechanism of nonmetal dopant for MoS2, and provides an efficient screening strategy for future catalyst design of transition metal dichalcogenides.

Effects of Ge addition on the structure, mechanical and magnetic properties of (CoCrFeNi)100-xGex high-entropy alloys

Alloying non-metallic elements can not only change the structure of alloys, but also tailor the mechanical and physical properties. The microstructure, mechanical and magnetic properties of (CoCrFeNi)100-xGex (molar ratio, x = 0 ∼ 33) high-entropy alloys (HEAs) have been systematically studied in this paper. The experimental results show that the (CoCrFeNi)100-xGex HEAs transform from a face-centered cubic (FCC) to a body-centered cubic (BCC) solid solution when 10 ≤ x ≤ 25, and a hexagonal intermetallic compound (IM) formed at x = 33. Tensile measurement revealed that the strength and plasticity of the alloy were enhanced simultaneously with Ge addition in the single FCC region (x ≤ 10), a decrease in ductility but sharp increase of strength was found in the alloys when the BCC phase starts to appear. Theoretical calculations and magnetic hysteresis loop measurements show that the alloys transform gradually from a paramagnetic to a ferromagnetic state at room temperature.

Front Cover: Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′‐P3N5, δ‐P3N5 and PN2 (Chem. Eur. J. 62/2022)

For the last 30 years, the lack of a binary phosphorus nitride containing PN6 octahedra formed a scientific chasm between carbon-group and oxygen-group nitrides, both featuring a variety of solids with XN6 units (X being a non-metal element). Now, the discovery of the δ-P3N5 and PN2 phosphorus nitrides—formed under high pressure and both composed of the elusive PN6 octahedron—builds a long-sought-after bridge between these two groups of nitrides. More information can be found in the Research Article by D. Laniel, F. Trybel, and co-workers (DOI: 10.1002/chem.202201998).

Graphitic carbon nitride (g-C3N4)-based photocatalytic materials for hydrogen evolution.

The semiconductors, such as TiO2, CdS, ZnO, BiVO4, graphene, produce good applications in photocatalytic water splitting for hydrogen production, and great progress have been made in the synthesis and modification of the materials. As a two-dimensional layered structure material, graphitic carbon nitride (g-C3N4), with the unique properties of high thermostability and chemical inertness, excellent semiconductive ability, affords good potential in photocatalytic hydrogen evolution. However, the related low efficiency of g-C3N4 with fast recombination rate of photogenerated charge carriers, limited visible-light absorption, and low surface area of prepared bulk g-C3N4, has called out the challenge issues to synthesize and modify novel g-C3N4-block photocatalyst. In this review, we have summarized several strategies to improve the photocatalytic performance of pristine g-C3N4 such as pH, morphology control, doping with metal or non-metal elements, metal deposition, constructing a heterojunction or homojunction, dye-sensitization, and so forth. The performances for photocatalytic hydrogen evolution and possible development of g-C3N4 materials are shared with the researchers interested in the relevant fields hereinto.

Urea Production on Metal-Free Dual Silicon Doped C9 N4 Nanosheet Under Ambient Conditions by Electrocatalysis: A First Principles Study.

The development of cheap, eco-friendly electrocatalysts for urea synthesis which avoids the traditional nitrogen reduction to form ammonia, is very important to meet our growing demand for urea. Herein, based on density functional theory, we propose a novel electrocatalyst (dual Si doped C9 N4 nanosheet) composed of totally environmentally benign non-metal earth abundant elements, which is able to adsorb N2 and CO2 together. Reduction of CO2 to CO happens, which is then inserted into activated N-N bond, and it produces *N(CO)N intermediate, which is the crucial step for urea formation. Eventually following several proton coupled electron transfer processes, urea is formed under ambient conditions. The limiting potential value for urea formation is found to be lower than that of NH3 formation and HER (hydrogen evolution reaction). Moreover, the faradaic efficiency of our proposed catalyst system is 100 % for urea formation, which suggests greater selectivity of urea formation over other competitive reactions.

A REVIEW: SULFUR IN COAL AND PETROLEUM COKE

sulfur (S), also spelled sulphur, nonmetallic chemical element belonging to the oxygen group (Group 16 [VIa] of the periodic table), one of the most reactive of the elements.Sulfur is classified among the minor constituents of Earth’s crust, in which its proportion is estimated to be between 0.03 and 0.06 percent. Coal is classified into four main types, or ranks: anthracite, bituminous, subbituminous, and lignite. Geochemical studies of sulfur in coals comprise several major aspects relating to the nature and origin of sulfur in coals, including the abundance and distribution of sulfur in coal seams, abundance of sulfur in coal lithotypes and macerals (Chen-Lin Chou, 2012). All types of coal also contain sulfur, which, when burned, releases toxic air pollution. Sulfur content is determined by the conditions under which the coal is formed. While Petroleum coke is a byproduct of petroleum refining, useful in the production of may things.

Tailoring cobalt‐free La 0.5 Sr 0.5 FeO 3‐δ cathode with a nonmetal cation‐doping strategy for high‐performance proton‐conducting solid oxide fuel cells

A nonmetal doping strategy was exploited for the conventional La0.5Sr0.5FeO3-δ (LSF) cathode, allowing high performance for proton-conducting solid oxide fuel cells (H-SOFCs). Unlike previous studies focusing on the utilization of metal oxides as dopants, phosphorus, which is a nonmetal element, was used as the cation dopant for LSF by partially replacing Fe ions to form the new La0.5Sr0.5Fe0.9P0.1O3-δ (LSFP) compound. The H-SOFC using the LSFP cathode showed a two-fold peak power density as compared to that using the LSF cathode.

Electrocatalytic hydrogen evolution performance of modified Ti3C2O2 doped with non-metal elements: A DFT study

Developing highly conductive, stable, and active hydrogen evolution reaction (HER) catalysts is a critical step towards establishing the hydrogen economy. However, there are few catalysts, except for noble metals, that can meet all the requirements. Recently, two-dimensional (2D) transition metal carbon/nitride (MXene) materials have shown excellent performance in catalysis, and have attracted wide attention from researchers. In this study, the effectiveness of non-metal element (B, C, N, P, and S)-doped Ti 3 C 2 O 2 MXene in the electrocatalytic hydrogen evolution reaction was investigated using density functional theory (DFT) calculations. Non-metal atoms as electron donors can provide additional electrons to the O functional group on the catalyst surface, thereby reducing charge transfer from H to O and the interaction between H and O. The Gibbs free energy (∆ G H ) of non-metal element-doped Ti 3 C 2 O 2 is closer to 0 than that of pristine Ti 3 C 2 O 2 , demonstrating better hydrogen evolution performance. Furthermore, in the hydrogen evolution path, the desorption process is more inclined to the Heyrovsky mechanism, and doping greatly reduces the energy barrier of the reaction, thereby improving the catalytic efficiency. The present results prove that doping with non-metallic elements is an effective means of improving the catalytic activity of Ti 3 C 2 O 2 for hydrogen evolution.

Effect of doping elements to hydrogen-free amorphous carbon coatings on structure and mechanical properties with special focus on crack resistance

The doping of amorphous carbon is one way of specifically modifying its properties. The present work is a contribution to understand the effect of dopant selection on structure, mechanical properties and crack resistance of hydrogen-free tetrahedral amorphous carbon (ta-C) coatings. For this purpose, nonmetallic (B, Si) and metallic (Mo, Fe, Cu) dopants were selected. The coatings were produced by the Laser-Arc technique and investigated by Raman spectroscopy, transmission electron microscopy, nanoindentation, bending, and scratch tests. It was found that doping generally affected the sp2 content and cluster size of the sp2 carbon phase, and thus hardness, Young's modulus, and intrinsic compressive stresses, but also the defect content and the crack resistance. The addition of metallic dopants led to an increase and clustering of the sp2-bonded carbon and, consequently, to a significant reduction in hardness and Young's modulus. This effect was much less pronounced when doping with non-metallic elements. The failure behavior changed toward higher ductility and crack resistance when metals were added. The crack resistance was found to be directly dependent on the H3/E2 value, with H3/E2 > 0.2 leading to a more brittle behavior with unstable crack propagation, while at H3/E2 < 0.2 the material was more ductile and exhibited stable crack propagation and thus higher crack resistance.

A first-principles study the effects of nitrogen on the lattice distortion, mechanical, and electronic properties of (ZrHfNbTa)C1-xNx high entropy carbonitrides

Recently, high-entropy carbonitrides (HECNs) have attracted extensive attentions due to their outstanding comprehensive properties. However, the underlying physical mechanisms responsible for their excellent properties are not well understood. In this work, the effects of nitrogen (N) on the material properties of the newly-developed (ZrHfNbTa)C1-xNx (x = 0.0–0.5) HECNs are systematically studied by the first-principles calculations. The obtained results reveal that the calculated properties of the HECNs match well with experimental data. The mechanical properties of the HECNs are closely associated with their local lattice distortion. The lattice distortion is exacerbated with the increase of N. Increasing N content also leads to increase their mass density and ductility, but decrease their lattice parameter, Young’s modulus, shear modulus, hardness, fracture toughness, acoustic velocity, Debye temperature, and thermal conductivity. The additive of N can promote the charge transfer between metal and non-metal elements, but decrease the strength of metal-carbon and metal-nitrogen bonds.

Regulating surface electron structure of PtNi nanoalloy via boron doping for high‐current‐density Li‐O2 batteries with low overpotential and long‐life cyclability

AbstractThe realization of high‐efficiency, reversible, stable, and safe Li‐O2 batteries is severely hindered by the large overpotential and side reactions, especially at high rate conditions. Therefore, rational design of cathode catalysts with high activity and stability is crucial to overcome the terrible issues at high current density. Herein, we report a surface engineering strategy to adjust the surface electron structure of boron (B)‐doped PtNi nanoalloy on carbon nanotubes (PtNiB@CNTs) as an efficient bifunctional cathodic catalyst for high‐rate and long‐life Li‐O2 batteries. Notably, the Li‐O2 batteries assembled with as‐prepared PtNiB@CNT catalyst exhibit ultrahigh discharge capacity of 20510 mA·h/g and extremely low overpotential of 0.48 V at a high current density of 1000 mA/g, both of which outperform the most reported Pt‐based catalysts recently. Meanwhile, our Li‐O2 batteries offer excellent rate capability and ultra‐long cycling life of up to 210 cycles at 1000 mA/g under a fixed capacity of 1000 mA·h/g, which is two times longer than those of Pt@CNTs and PtNi@CNTs. Furthermore, it is revealed that surface engineering of PtNi nanoalloy via B doping can efficiently tailor the electron structure of nanoalloy and optimize the adsorption of oxygen species, consequently delivering excellent Li‐O2 battery performance. Therefore, this strategy of regulating the nanoalloy by doping nonmetallic elements will pave an avenue for the design of high‐performance catalysts for metal‐oxygen batteries.

Promotional Effects on the Catalytic Activity of Co-Fe Alloy Supported on Graphitic Carbon for CO2 Hydrogenation.

Starting from the reported activity of Co-Fe nanoparticles wrapped onto graphitic carbon (Co-Fe@C) as CO2 hydrogenation catalysts, the present article studies the influence of a series of metallic (Pd, Ce, Ca, Ca, and Ce) and non-metallic (S in various percentages and S and alkali metals) elements as Co-Fe@C promoters. Pd at 0.5 wt % somewhat enhances CO2 conversion and CH4 selectivity, probably due to H2 activation and spillover on Co-Fe. At similar concentrations, Ce does not influence CO2 conversion but does diminish CO selectivity. A 25 wt % Fe excess increases the Fe-Co particle size and has a detrimental effect due to this large particle size. The presence of 25 wt % of Ca increases the CO2 conversion and CH4 selectivity remarkably, the effect being attributable to the CO2 adsorption capacity and basicity of Ca. Sulfur at a concentration of 2.1% or higher acts as a strong poison, decreasing CO2 conversion and shifting selectivity to CO. The combination of S and alkali metals as promoters maintain the CO selectivity of S but notably increase the CO2 conversion. Overall, this study shows how promoters and poisons can alter the catalytic activity of Co/Fe@C catalysts, changing from CH4 to CO. It is expected that further modulation of the activity of Co/Fe@C catalysts can serve to drive the activity and selectivity of these materials to any CO2 hydrogenation products that are wanted.

Eutectic high entropy alloys containing B and Si with excellent mechanical properties in annealing

Eutectic high-entropy alloys (EHEAs), combined with good castability and exceptional properties, are becoming hotpots in the field of metallic materials. It is worth noting that the most reported EHEAs are composed of metallic elements, and the EHEAs containing non-metallic elements have been rarely reported. In this work, four novel EHEAs containing B and Si with face-centered-cubic and M3B2-type boride were designed and prepared. After a simple annealing, they exhibited high ultimate tensile strength (1048 MPã1140 MPa) and good fracture ductility (4.1%–14.7%). Compared with the as-cast alloys, the fracture ductility of the four annealing EHEAs increases by 3.4–6.1 times, while the ultimate tensile strength shows practically no reduction. The outstanding mechanical properties were attributed to the fragmentation and spheroidization of M3B2-type boride, which not only reduces the nucleation positions of microcracks, but also widens the distance across which the cracks connect.

Determination of the most informative chemical elements for discrimination of rice samples according to the producing region

Several approaches to assess the authenticity of food products have been developed, given that fraudulent products may impact consumers' confidence, affect commercial trades and lead to health risks. This paper proposes an approach to identify the chemical elements that optimally discriminate rice samples according to their producing region in the South of Brazil, the largest rice producer outside Asia. A combinatorial procedure on the concentration of 26 elements determined using inductively coupled mass spectrometry (ICP-MS) and liquid chromatography hyphenated with ICP-MS from 640 rice samples was coupled with Support Vector Machine. The assessed elements included nonmetal and metal elements of 3 types of rice collected from 5 rice-producing regions. The framework selected Mn, Fe, Cu, Zn, Ni, Mo, Cd, Cs, As, Rb, Se, and iAs as the most informative elements for tracking samples’ origin. The concentration of such elements is strongly affected by fertilization procedures and soil composition.

Strain-engineered S-HfSe2 monolayer as a promising gas sensor for detecting NH3: A first-principles study

The development of high-performance gas sensing materials is one of the development trends of new gas sensor technology. In this work, in order to predict the gas-sensitive characteristics of HfSe2 and its potential as a gas-sensitive material, the interactions of nonmetallic element (O, S, Te) doped HfSe2 monolayer and small molecules (NH3 and O3) have been studied by first-principles based on density functional theory. The results show that the adsorption of NH3 and O3 on pristine HfSe2 monolayer is weak, and the adsorption strength can be significantly improved by doping O. And O-HfSe2 is chemical adsorption to O3 with large adsorption energy and transfer charge, and the band gap of OHfSe2 disappears after adsorbing O3, indicating that the adsorption of O3 has a significant effect on the electrical properties of the substrate. These mean that O3 is difficult to recover from the substrate surface, thus preventing O-HfSe2 from developing into a sensitive material for O3 detection. After doping S, the charge transfers and adsorption strength to NH3 are the largest, but it is still small. So, the strain effect on the S-HfSe2/NH3 adsorption system is also studied. The results indicate that the adsorption strength of S-HfSe2 to NH3 can be enhanced by stretching S-HfSe2 along x-axis. After absorbing NH3, the conductivity of x-axis strained S-HfSe2 changes, which suggest its sensitivity. And the predicted recovery times of S-HfSe2 surfaces with εx=4%, 6% and 8% are 0.027 s, 1.153 s and 102.467 s, respectively, which suggests that the S-HfSe2 monolayer has the potential to be developed as a sensitive material for NH3 detection. These adsorption mechanism studies can also serve as a theoretical foundation for the experimental design of gas-sensing materials.

Reexamining the heavy-atom-effect: The universal heavy-atom-induced fluorescence enhancement principle for through-space conjugated AIEgens

The heavy-atom effect is a classic photophysical principle that dominates heavy-atom-induced fluorescence quenching and phosphorescence enhancement and has been universally suited for conventional luminogens with through-bond conjugation; however, its universality to emerging AIEgens (i.e., luminogens exhibiting aggregation-induced emission) with through-space conjugation is questionable. Herein, a series of tetraphenylethylene (TPE)-based AIEgens containing diverse non-metallic elements were designed by introducing each non-metallic element into the typical TPE skeleton, and their abnormal heavy-atom-induced fluorescence enhancement behaviors were examined against the classic heavy-atom effect. The underlying nature of heavy-atom-induced fluorescence enhancement was experimentally and theoretically explored. It was found that both insignificant heavy-atom-induced intersystem crossing processes (owing to the intrinsic through-space conjugation feature) and significant heavy-atom-induced restriction of the intramolecular vibrations cooperatively contribute to such an abnormal fluorescence enhancement. In addition, this principle was found to be universally applicable to TPE-based AIEgens containing other heavy atoms, which validates the universality of the heavy-atom-induced fluorescence enhancement principle for typical AIEgens with through-bond and through-space conjugation. In summary, this study re-examined the classic heavy-atom effect from a completely fresh perspective of emerging AIEgens and proposed a universal heavy-atom-induced fluorescence enhancement principle suited for most AIEgens.