Electrostatic Potential Difference Research Articles

Influence of IDS and SDS compound ratio on pore structure and wettability of bituminous coal and anthracite: Experimental and simulation discussion

The pore and wetting characteristics of bituminous coal and anthracite treated with different proportions of tetrasodium iminodisuccinate (IDS) and sodium dodecyl sulfate (SDS) were measured. The pore structure characteristics of the coal were studied via low-temperature nitrogen adsorption analysis and the Frenkel-Halsey-Hill fractal theory. Zeta potential measurements were conducted to quantitatively analyze the degree of aggregation or dispersion of coal particles dissolved in solution. Changes in the coal surface morphology were observed and analyzed by scanning electron microscopy (SEM). The results show that when the ratio of IDS:SDS is 1:3, the specific surface area (SSA) values of bituminous coal and anthracite are the lowest. The composite reagent has a greater effect on improving the pore structure of anthracite than bituminous coal. Compared with bituminous coal, anthracite has better pore connectivity and a wider pore network. The absolute zeta potentials of bituminous coal and anthracite reach the maximum at an IDS:SDS ratio of 1:3, with values of 91.08 mV and 91.35 mV, respectively. The electrostatic potential distributions of the molecules show that the advantages of the electrostatic potential difference with water molecules enable IDS and SDS molecules to effectively attract water molecules and form hydrogen bonds, thus revealing the optimization mechanism of coal wettability.

Harnessing intrinsic electric fields in 2D Janus MoOX (X=S, Se, and Te) monolayers for enhanced photocatalytic hydrogen evolution

Two-dimensional (2D) Janus monolayers, distinguished by their intrinsic vertical electric fields, emerge as highly efficient and eco-friendly materials for advancing the field of hydrogen evolution reactions (HER). In this study, we explore, for the first time, the potential viability of the oxygenation phase of two-dimensional Janus transition metal dichalcogenides MoOX (X = S, Se, and Te) monolayers as an exceptionally efficient photocatalyst for hydrogen production. Based on first-principles computations, we demonstrate that all three monolayers exhibit semiconductor behavior, characterized by a band gap ranging from 0.66 to 1.55 eV. This narrow band gap renders the proposed materials highly efficient at absorbing light within the visible region. Excitingly, the introduction of an electrostatic potential difference ΔΦ has granted us the ability to surpass the conventional bandgap limit (Eg≥1.23). Consequently, all monolayers exhibit favorable band alignment with respect to the vacuum level. Moreover, the calculated solar-to-hydrogen efficiency for the envisaged monolayer exceeds the established theoretical limit. Particularly, the MoOTe monolayer emerges as an infrared-light-driven photocatalyst, demonstrating a remarkable solar-to-hydrogen efficiency limit of up to 25,21% when considering the entire solar spectrum. A thorough examination of the Gibbs free energy differences across these monolayers has revealed that the values during the oxygenation phase are significantly smaller and approach the optimum, in contrast to the parental two-dimensional Janus transition metal dichalcogenides. Our results conclusively establish that the proposed materials exhibit exceptional efficiency as photocatalysts for hydrogen evolution reactions. Notably, their efficacy is demonstrated even in the lack of co-catalysts or sacrificial agents.

Constructing Directional Electrostatic Potential Difference via Gradient Nitrogen Doping for Efficient Oxygen Reduction Reaction.

Nitrogen doping has been recognized as an important strategy to enhance the oxygen reduction reaction (ORR) activity of carbon-encapsulated transition metal catalysts (TM@C). However, previous reports on nitrogen doping have tended to result in a random distribution of nitrogen atoms, which leads to disordered electrostatic potential differences on the surface of carbon layers, limiting further control over the materials' electronic structure. Herein, a gradient nitrogen doping strategy to prepare nitrogen-deficient graphene and nitrogen-rich carbon nanotubes encapsulated cobalt nanoparticles catalysts (Co@CNTs@NG) is proposed. The unique gradient nitrogen doping leads to a gradual increase in the electrostatic potential of the carbon layer from the nitrogen-rich region to the nitrogen-deficient region, facilitating the directed electron transfer within these layers and ultimately optimizing the charge distribution of the material. Therefore, this strategy effectively regulates the density of state and work function of the material, further optimizing the adsorption of oxygen-containing intermediates and enhancing ORR activity. Theoretical and experimental results show that under controlled gradient nitrogen doping, Co@CNTs@NG exhibits significantly ORR performance (Eonset=0.96V, E1/2=0.86V). At the same time, Co@CNTs@NG also displays excellent performance as a cathode material for Zn-air batteries, with peak power density of 132.65mAcm-2 and open-circuit voltage (OCV) of 1.51V. This work provides an effective gradient nitrogen doping strategy to optimize the ORR performance.

Enhancing Electrochemical Signal for Efficient Chiral Recognition by Encapsulating C60 Fullerene into Chiral Lanthanum-Based MOFs.

Chiral metal-organic frameworks (MOFs) have attracted much attention due to their highly tunable regular microporous structures. However, chiral electrochemical recognition based on chiral MOFs is often limited by poor charge separation and slow charge transfer kinetics. In this case, C60 can be encapsulated into the cavity of [La(BTB)]n by virtue of host-guest interactions through π-π stacking to synthesize the chiral composite C60@[La(BTB)]n and amplify electrochemically controlled enantioselective interactions with the target enantiomers. A large electrostatic potential difference is generated in chiral C60@[La(BTB)]n due to the host-guest interaction and the inhomogeneity of the charge distribution, leading to the generation of a strong built-in electric field and thus an overall enhancement of the conductivity of the chiral material. Their enantioselective detection of tryptophan enantiomers was demonstrated by electrochemical measurement. The results showed that chiral MOF materials can be used for enantiomeric recognition. It is worth noting that this new material derived from the concept of host-guest interaction to enhance charge separation opens up unprecedented possibilities for future enantioselective recognition and separation.

Preference in the Type of Halogen Bonding Interactions within Co-Crystals of Anthraquinone with a Pair of Isosteric Perhalobenzenes

The preference in the type of halogen bond accepted by anthraquinone (C14H8O2) from two isosteric donors, namely 1,4-diiodoperfluorobenzene (C6I2F4) and 1,4-diiodoperchlorobenzene (C6I2Cl4), is reported. The two co-crystals, (C6I2F4)·(C14H8O2) and (C6I2Cl4)·(C14H8O2), are sustained primarily by I···O rather than π-type halogen bonds to form these multicomponent solids. The ability for each component to engage in two divergent halogen-bonding interactions generates a one-dimensional chain structure for each co-crystal. The bias in the halogen-bonding type is due to the difference in electrostatic potential between the carbonyl oxygen and the aromatic surface on the anthraquinone. To support this observed preference, the binding energies of the I···O halogen bond were quantified for both co-crystals by using density functional theory calculations and then compared to the interaction energy for related π-type halogen bond from previously reported structures.

The investigation of wetting and agglomerating mechanism of short-chain fluorocarbon surfactant suppressing coal dust from macro and molecular scales

This paper carried out a multi-scale investigation on the wetting and agglomerating mechanism of short-chain fluorocarbon surfactant suppressing coal dust. As investigated, FS-50 achieves higher dedusting rate and shorter suppression time than FS-3100, which is attributed to its better wettability and more sufficient agglomeration on coal particles. Simulation indicates that FS-3100 with longer chain length is easier to generate chemical bond rotation, which results in a distorted spatial structure, higher steric hindrance, and poorer ability of FS-3100 in retaining H2O molecules and adsorbing surround the coal particles. The hydrophilic group of FS-50 is dominated by the induced effect and presenting larger charge density and electron-absorbing nature. Higher electrostatic potential difference with coal molecules, more hydrogen bonds, shorter bond length and larger bond angle are key factors to endorse FS-50 a better wetting and agglomerating performance. The C atom connected with the fluorocarbon tail chain of FS-3100 is linked to a carboxyl group with lone pair electrons. This carboxyl group enlarges the LUMO value of FS-3100 and weaken its ability to attract the electrons of coal particles. On the contrary, the lower LUMO value, lower band gap energy, and smoother spatial configuration jointly bring FS-50 better wetting and agglomerating ability.

Concentrated aqueous solutions of multivalent macroions enhance the electrical double layer capacitance and differential capacitance of a planar supercapacitor

The electrostatic properties of the ionic cloud, or electrical double layer, neutralizing a charged electrode are relevant to improve the storage of electrical energy and the efficiency of supercapacitors and/or batteries using coulombic fluids. In this work, we study the microscopic profiles of charged particles, integrated surface charge density, and the mean electrostatic potential associated to a pair of infinite parallel plates uncharged or, else, with opposite charge, in the presence of a salt-free aqueous solution constituted by big positive macroions and small anions, which interact via an explicit electrostatic coulombic potential and are dissolved in an implicit solvent. The particle profiles and the integrated surface charge density associated to Monte Carlo simulations and integral equations theory display an oscillatory or non-monotonic behaviour producing the phenomena of charge inversion and charge reversal. These phenomena are not predicted by the non-linear Poisson-Boltzmann equation, which highlights the importance of ion correlations and ionic volume excluded effects. The phenomenon of surface charge amplification is observed near the point of zero charge, which is yielded by the particle size-asymmetry. For a fixed concentration of macroions, a monotonic increase of the mean electrostatic potential difference between the charged parallel plates is predicted by simulations and theories as a function of the electrodes' charge. For a fixed surface charge density, the capacitance of the parallel plates capacitor increases when the ionic strength of the macroion's solution increases. A concavity inversion and an augment of the differential capacitance is also observed for an electrode near the point of zero charge as function of the macroion's concentration.

Two Completely Non‐Fused Ring Acceptors Working in an Alloy‐Like Model for Efficient and Stable Organic Solar Cells

AbstractSimple chemical structure and simplified synthesis process of active layer materials are critical for advancing the practical application of organic solar cells. Herin, two completely non‐fused ring electron acceptors BTZT‐2Cl and BTZT‐4Cl are developed. BTZT‐4Cl exhibits an enhanced absorption band, increases electrostatic potential differences with D18, and improves crystallinity and molecular packing properties. Consequently, the binary device based on BTZT‐4Cl displays a markedly improved efficiency of 14.12%, compared to the BTZT‐2Cl‐based device, which only achieves a moderate efficiency of 11.25%. More importantly, an alloy‐like structure can be formed by incorporating a small amount of high miscibility and compatibility BTZT‐2Cl. The ternary blend exhibits more compact molecular packing, efficient exciton dissociation, and an extended charge carrier lifetime due to the formation of an alloy‐like structure. The ternary device achieves a decent efficiency of 15.41% with superior thermal stability and a high T80 lifetime over 1600 h after being aged at 65 °C. These results establish it as the most efficient among devices based on completely non‐fused ring acceptors with both high efficiency and voltage. This study demonstrates a simple material design strategy and high‐performance device optimization techniques, which are critical for advancing practical applications in the OSC field.

A novel AA14 LPMO from Talaromyces rugulosus with bifunctional cellulolytic/hemicellulolytic activity boosted cellulose hydrolysis

BackgroundThe recently discovered PcAA14A and B from white-rot basidiomycete Pycnoporus coccineus enriched our understanding of the oxidative degradation of xylan in fungi, however, the unusual mode of action of AA14 LPMOs has sparked controversy. The substrate specificity and functionality of AA14 LPMOs still remain enigmatic and need further investigation.ResultsIn this study, a novel AA14 LPMO was characterized from the ascomycete Talaromyces rugulosus. TrAA14A has a broad substrate specificity with strong oxidative activity on pure amorphous cellulose and xyloglucan. It could simultaneously oxidize cellulose, xylan and xyloglucan in natural hemi/cellulosic substrate such as fibrillated eucalyptus pulp, and released native and oxidized cello-oligosaccharides, xylo-oligosaccharides and xyloglucan oligosaccharides from this substrate, but its cellulolytic/hemicellulolytic activity became weaker as the contents of xylan increase in the alkaline-extracted hemi/cellulosic substrates. The dual cellulolytic/hemicellulolytic activity enables TrAA14A to possess a profound boosting effect on cellulose hydrolysis by cellulolytic enzymes. Structure modelling of TrAA14A revealed that it exhibits a relatively flat active-site surface similar to the active-site surfaces in AA9 LPMOs but quite distinct from PcAA14B, despite TrAA14A is strongly clustered together with AA14 LPMOs. Remarkable difference in electrostatic potentials of L2 and L3 surfaces was also observed among TrAA14A, PcAA14B and NcLPMO9F. We speculated that the unique feature in substrate-binding surface might contribute to the cellulolytic/hemicellulolytic activity of TrAA14A.ConclusionsThe extensive cellulolytic/hemicellulolytic activity on natural hemi/cellulosic substrate indicated that TrAA14A from ascomycete is distinctively different from previously characterized xylan-active AA9 or AA14 LPMOs. It may play as a bifunctional enzyme to decompose some specific network structures formed between cellulose and hemicellulose in the plant cell walls. Our findings shed new insights into the novel substrate specificities and biological functionalities of AA14 LPMOs, and will contribute to developing novel bifunctional LPMOs as the booster in commercial cellulase cocktails to efficiently break down the hemicellulose-cellulose matrix in lignocellulose.

Secretory CAZymes profile and GH19 enzymes analysis of Corallococcus silvisoli c25j21.

Extracellular enzymes play important roles in myxobacteria degrading macromolecules and preying on other microorganisms. Glycoside hydrolases 19 (GH19) are widely present in myxobacteria, but their evolution and biological functions have not been fully elucidated. Here we investigated the comparative secretory proteome of Corallococcus silvisoli c25j21 in the presence of cellulose and chitin. A total of 313 proteins were detected, including 16 carbohydrate-active enzymes (CAZymes), 7 of which were induced by cellulose or chitin, such as GH6, GH13, GH19, AA4, and CBM56. We further analyzed the sequence and structural characteristics of its three GH19 enzymes to understand their potential functions. The results revealed that myxobacterial GH19 enzymes are evolutionarily divided into two clades with different appended modules, and their different amino acid compositions in the substrate binding pockets lead to the differences in molecular surface electrostatic potentials, which may, in turn, affect their substrate selectivity and biological functions. Our study is helpful for further understanding the biological functions and catalytic mechanisms of myxobacterial CAZymes.

Impact of Electrostatic Interaction on Vertical Morphology and Energy Loss in Efficient Pseudo-Planar Heterojunction Organic Solar Cells.

Although a suitable vertical phase separation (VPS) morphology is essential for improving charge transport efficiency, reducing charge recombination, and ultimately boosting the efficiency of organic solar cells (OSCs), there is a lack of theoretical guidance on how to achieve the ideal morphology. Herein, a relationship between the molecular structure and the VPS morphology of pseudo-planar heterojunction (PPHJ) OSCs is established by using molecular surface electrostatic potential (ESP) as a bridge. The morphological evolution mechanism is revealed by studying four binary systems with vary electrostatic potential difference (∆ESP) between donors (Ds) and acceptors (As). The findings manifest that as ∆ESP increases, the active layer is more likely to form a well-mixed phase, while a smaller ∆ESP favors VPS morphology. Interestingly, it is also observed that a larger ∆ESP leads to enhanced miscibility between Ds and As, resulting in higher non-radiative energy losses (ΔE3). Based on these discoveries, a ternary PPHJ device is meticulously designed with an appropriate ∆ESP to obtain better VPS morphology and lower ΔE3, and an impressive efficiency of 19.09% is achieved. This work demonstrates that by optimizing the ΔESP, not only the formation of VPS morphology can be controlled, but also energy losses can be reduced, paving the way to further boost OSC performance.

Narcissistic self-sorting in Zn(II) porphyrin derived semiconducting nanostructures.

The narcissistic self-sorted phenomenon is explicitly attributed to the structural similarities in organic molecules. Although such relevant materials are rarely explored, self-sorted structures from macrocyclic π-conjugated-based p- and n-type organic semiconductors facilitate the increase of exciton dissociation and charge separation in bulk heterojunction solar cells. Herein, we report two extended π-conjugated derivatives consisting of zinc-porphyrin-linked benzothiadiazole acting as an acceptor (PB) and anthracene as a donor (PA). Despite having the same porphyrin π-conjugated core in PA and PB, variations in donor and acceptor moieties make the molecular packing form one-dimensional (1D) self-assembled nanofibers via H- and J-type aggregates. Interestingly, a dissimilar aggregate of PA and PB exists as a mixture (PA + PB), promoting narcissistic self-sorted structures. Electrochemical impedance investigation reveals that the electronic characteristics of self-sorting assemblies are influenced by the difference in electrostatic potentials for PA and PB, resulting in a transitional electrical conductivity of 0.14 S cm-1. Therefore, the design of such materials for the fabrication of effective photovoltaics is promoted by these extraordinary self-sorted behaviors in comparable organic π-conjugated molecules.

Unravelling ionic liquid solvent effects for a non-polar Cope rearrangement reaction.

The impact of ionic liquids (ILs) on polar reactions is well recognised, however the impact of ILs on non-polar reactions is less well understood or explored. Pericyclic Cope rearrangements are highly concerted, exhibit minimal charge localisation and pass through an uncharged but well-defined transition state, and thus provide a good mechanism for exploring the impact of IL polarizability on chemical reactivity. Recently, a 10× rate enhancement has been observed for the Cope rearrangement of 3-phenyl-1,5-hexadiene in the IL 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4C1im][NTf2] compared to benzene. In this work we undertake a DFT based computational study (B3LYP-D3BJ/6-311+G(d,p) and M06-2X-D3/6-311+G(d,p)) of the Cope rearrangement of 3-phenyl-1,5-hexadiene and 3-propyl-hexa-1,5-diene in molecular solvents (acetonitrile, benzene and ethanol) and the IL [C4C1im][NTf2] using the SMD solvation model. The impact of benzene and [C4C1im][NTf2] on the Cope rearrangement of 3-phenyl-1,5-hexadiene is studied in more detail and we provide insight into the reason for the rate enhancement in an IL. The volume of activation is evaluated and the potential impact of 'solvent pressure' is discussed. We identify two potential mechanisms for volume effects to contribute to the rate enhancement. Solvent association energies are evaluated at the DLNPO-CCSD(T) level. Specific solvent interactions are explored through atomic partial charge, molecular orbital and bond critical point analysis, as well as via non-colvalent interaction (NCI) plots, electrostatic potential (ESP) differences and density difference Δρ(r) plots. We find that the cation and anion together form an extensive van der Waals pocket in-which the transition state (TS) sits. Electron density within the TS is anisotropically polarised via a 'push-pull' effect due to the dual cation-anion nature of the IL, stabilising the TS relative to benzene. We also provide experimental evidence that these effects are generalisable to other ILs. Overall, our aim is to provide a deeper moleuclar level understanding of the impact of ILs on non-polar reactions.

Acceptor-donor-acceptor-type molecules with large electrostatic potential difference for effective NIR photothermal therapy.

Although acceptor-donor-acceptor (A-D-A)-type molecules offer advantages in constructing NIR absorbing photothermal agents (PTAs) due to their strong intramolecular charge transfer and molecular planarity, their applications in photothermal therapy (PTT) of tumors remain insufficiently explored. In particular, the influence of ESP distribution on the optical properties of A-D-A photosensitizers has not been investigated. Herein, we analyze and compare the difference in ESP distribution between A-D-A-type small molecules and polymers to construct NIR absorbing PTAs with a high extinction coefficient (ε) and high photothermal conversion efficiency (PCE). The calculation results of density functional theory (DFT) indicate that the large ESP difference makes A-D-A-type small molecules superior to their polymer counterparts in realizing tight molecular packing and strong NIR absorbance. Among the as-prepared nanoparticles (NPs), Y6 NPs exhibited an obvious bathochromic shift of absorption peak from 711 nm to 822 nm, with the NIR-II emission extended to 1400 nm. Moreover, a high ε value of 5.69 L g-1 cm-1 and a PCE of 66.3% were attained, making Y6 NPs suitable for PTT. With a concentration of 100 μg mL-1, Y6 NPs in aqueous dispersion yielded a death rate of 93.4% for 4T1 cells upon 808 nm laser irradiation (1 W cm-2) for 10 min, which is comparable with the best results of recently reported PTT agents.

Efficient photoreduction of carbon dioxide to acetaldehyde on monatomic defective black phosphorus

Conversion of CO2 into C2 products has been challenging, largely due to the insufficient electron deliverability of catalyst. Here we proposed latent monatomic defective black phosphorus (BPV), on which the efficient photoreduction of CO2 to CH3CHO was confirmed by density functional theory (DFT) calculations. The electrostatic potential difference between the upper and lower atoms of the BPV was found responsible for the enhanced separation of electrons and holes. The COCO coupling was studied, the charge transfer from BPV to CO (0.38 |e|) was found contributes to the enhanced CO2 reduction reaction (CO2RR) activity and promoted COCO coupling process. This work provides theoretical guidelines on the design of defect catalyst for CO2 photoreduction.

Mutation of AtPME2, a pH-Dependent Pectin Methylesterase, Affects Cell Wall Structure andHypocotyl Elongation.

Pectin methylesterases (PMEs) modify homogalacturonan's chemistry and play a key role in regulating primary cell wall mechanical properties. Here, we report on Arabidopsis AtPME2, which we found to be highly expressed during lateral root emergence and dark-grown hypocotyl elongation. We showed that dark-grown hypocotyl elongation was reduced in knock-out mutant lines as compared to the control. The latter was related to the decreased total PME activity as well as increased stiffness of the cell wall in the apical part of the hypocotyl. To relate phenotypic analyses to the biochemical specificity of the enzyme, we produced the mature active enzyme using heterologous expression in Pichia pastoris and characterized it through the use of a generic plant PME antiserum. AtPME2 is more active at neutral compared to acidic pH, on pectins with a degree of 55-70% methylesterification. We further showed that the mode of action of AtPME2 can vary according to pH, from high processivity (at pH8) to low processivity (at pH5), and relate these observations to the differences in electrostatic potential of the protein. Our study brings insights into how the pH-dependent regulation by PME activity could affect the pectin structure and associated cell wall mechanical properties.

Unveiling the potential of two-dimensional Janus ScXAlY (X/Y=P, As) materials and heterostructures in visible-light-driven photocatalytic water splitting

Two-dimensional (2D) material with Janus-induced built-in electric field, has become a research focus arising from their characteristic physical and chemical properties, especially in photocatalytic water splitting applications. Herein, we introduce a novel family of 2D Janus materials, named ScXAlY (X/Y = P, As), and prove these Janus materials and their heterostructures as promising water splitting photocatalytic candidate materials, leveraging first-principles calculations. All Janus structures and heterostructures exhibit strong dynamical, thermal, and mechanical stabilities. These 2D Janus ScXAlY materials possess wide band gaps, excellent electronic carrier mobilities, and appropriate band edges to facilitate overall water splitting, and moreover can attain Janus-induced built-in electric field effect. Interestingly, the heterostructures (ScXAlY/ScXAlY) surpass the individual materials in performance, demonstrating enhanced solar-to-hydrogen (STH) efficiencies (>30 %) and increscent electrostatic potential differences (>0.85 eV). Furthermore, they show comprehensive photoabsorption across the visible light spectrum, with peak absorptions more than doubling those of the single materials. These heterostructures also display effective spatial separation of electrons and holes which can further boosting their photocatalytic capabilities. Our findings underscore the potential of Janus ScXAlY materials and their heterostructures, in facilitating visible-light-driven photocatalytic water splitting, showcasing a promising avenue for advancement in this burgeoning field.

Theoretical investigations on CL‑20/TNBA co-crystal explosive via density functional method and molecular dynamics method

The study of CL-20 co-crystal has always been a focal point within the field of energetic material modification. In this study, we employed the density functional method and molecular dynamics method to investigate the properties of hexanitrohexaazaisowurtzitane (CL-20)/ 2,4,6-trinitro-3-bromoanisole (TNBA) with different molar ratios ranging from 9:1–1:9. This investigation encompassed surface electrostatic potential, atomic interaction line, binding energy, trigger bond length, radial distribution function, cohesive energy density, and mechanical properties. Additionally, EXPLO-5 software was utilized to predict the detonation properties and products of pure CL-20, TNBA, and CL-20/TNBA systems. The results revealed significant differences in the surface electrostatic potential between CL-20 and TNBA molecules, indicating stronger interactions between different molecules than between identical molecules and suggesting the potential for co-crystal formation. At the molar ratio of 5:5, the binding energy was found to be the highest, signifying the most likely formation of a co-crystal. The main driving forces for co-crystal formation were electrostatic force and van der Waals force. The co-crystal explosive exhibited moderate sensitivity and excellent mechanical properties. Furthermore, the co-crystal detonation performance at a molar ratio of 5:5 was between that of CL-20 and TNBA, representing a new type of insensitive high-energy material.

Two-dimensional Janus B2P6 as potential gas sensors for NO and NO2 detection: A first-principles study

The adsorption properties of novel Janus B2P6 nanosheet with NO and NO2 on both sides are researched by DFT calculation. The results show that the (001) surface exhibits moderate adsorption energies of −0.38 eV for NO and −0.42 eV for NO2. It is found that the electronic properties of Janus B2P6 are affected obviously by NO2 adsorption on the (001) surface, where the bandgap energy is decreased by 1.14 eV and the magnetic moment of 0.93 μB is induced, indicating Janus B2P6 exhibits better sensitivity to NO2. Note that the recovery times of NO and NO2 are found to be 2.4 and 11.0 μs, facilitating the reuse of devices. And a large diffusion energy barrier is found to ensure the stable transmission of signal. Moreover, under biaxial strain of −2%, the adsorption energy of NO on the (001) surface is greatly reduced to −0.24 eV, favoring the desorption of gas molecules. Verifiably, the combined variation of the electrostatic potential difference and the bonding environment leads to differences in the adsorption behavior. These findings demonstrate the potential of Janus B2P6 as ultra-sensitive strain gas sensors.

Interactions between fluorocarbon surfactant and coal dust at macro, meso and molecular scales and their applications in coal dust control

Surfactants play an important role in the field of coal dust prevention, among which fluorocarbon surfactants have the advantages of low surface tension and have the potential to become mine dust suppressants. In this study, the wettability of fluorocarbon surfactant (OBS) on coal dust was studied from macro experiments, meso dust mist coupling and micro molecular simulation. The results showed that the surface tension of 0.06% OBS was as low as 17.6 mN/m, and the median particle size of coal dust reached 60.25 μm after wetting coal dust. Coal dust particles are easier to bond with each other into large particles, thus promoting settlement; During the meso collision between droplets and coal dust particles, OBS droplets showed excellent wetting and spreading effect, and the droplet state was stable, and the optimal spraying velocity was determined to be 20–30 m/s; At the molecular level, the diffusion coefficient of water molecules in the OBS system is minimally 0.46 Å2/ps, indicating a strong ability to constrain water molecules. The strength and energy of the hydrogen bonds formed with water molecules were greater than those of hydrocarbon surfactants, resulting in the best adsorption of water molecules. Additionally, it was found that the law of attractive and competitive adsorption of different surfactants in wetting coal dust is based on the difference in positive and negative electrostatic potential, where the greater the difference, the stronger the interaction. This provides a theoretical reference for judging the wetting performance of different surfactants at the molecular level.