Amount Of Charge Transfer Research Articles

Electronic and Magnetic Properties of Cobalt Clusters on Pristine and Divacancy Graphene

Using ab initio calculations we investigate the adsorption of Co atoms, dimers and small cobalt clusters of 5 and 13 atoms on pristine graphene and graphene with a double vacancy. We report the atomic, electronic, magnetic and energetic properties of these systems. Stable adsorption configurations tend to maximize the number of cobalt-carbon bonds. On graphene, the adsorption energy of the clusters is only about 0.4 to 1 eV, and the clusters are relatively mobile on graphene. Interestingly, for different adsorbed Co13 isomers on graphene it is found that they converge to the same atomic structure. On graphene with a divacancy, the Co clusters bind in the divacancy site and isomerisation also occurs for the Co5 cluster system as well as for Co13. Co atoms and clusters can be effectively immobilized on the divacancy with corresponding adsorption energy being significantly enhanced by about 5 to 7 eV. All clusters act as electron donors in the interaction with the graphene/divacancy systems, and the amount of electron charge transfer increases with cluster size. Finite magnetic moments occur for all systems, where upon adsorption, the magnetic moment of the isolated Co atom (3μB) is significantly reduced due to electron transfer and bonding, resulting in values varying from ≈0.9-2.2 μB per Co atom. For the pristine graphene substrate, the total induced magnetic moments on the carbon atoms are negligible, while on the divacancy system, they are of the order of 0.1-0.3 μB. The attractive physical properties of these hybrid systems could find applications in catalysis and materials science.

Supplanted by electron-deficient B to form RuN2B-CoN4 moiety as superior catalytic site to further promote urea production

The potential significance of electrocatalytic urea synthesis as a promising alternative to traditional manufacture is widely recognized. However, the critical hindrance is lack of its highly efficient and robust electrocatalysts until now. Alongside the exploration of novel urea catalysts, it is equally crucial to explore feasible strategies to boost the performance of the identified active sites. In this work, we proposed and demonstrated a modulatory scheme to further promote urea production in Ru-Co dual-metal sites through the substitution of electron-deficient B atom in RuN3 subunit to form RuN2B-CoN4 moiety in graphene. The B-coordinated Ru active site can effectively decrease charge transfer amount from the Ru atom to the substrate. The enhanced single-atomic similarity to free Ru atom results in more negative adsorption energy for N2 molecule and superior catalytic activity/selectivity for urea generation. More significantly, this study provides a new perspective to promote the catalytic performance of the carbon-based diatomic active sites for urea production.

Investigating the impact of acetylenic linkage in C20 fullerene: Utilization in optoelectronic devices and as anode material

This study delves into the diverse characteristics of C80 fulleryne, derived from the incorporation of acetylenic linkages into each chain of the smallest fullerene, C20. Utilizing advanced theoretical computations, we confirm the stability of C80 fulleryne. Notably, its possession of a finite energy gap (0.743 eV) categorizes it as a semiconductor. Further enlightenment into its structural stability, bonding and reactivity stems from an exploration of different energy components, topological descriptors of electron density and chemical reactivity parameters. C80 fulleryne can act as radical scavenger owing to its higher electron affinity (5.5 eV). Spectral analysis revealed the C80 fulleryne’s absorption within the near-infrared region and its intriguing optical transparency with negligible loss in specific regions of the electromagnetic spectrum. Additionally, our investigation scrutinized the viability of C80 fulleryne as an anode material in Lithium-ion batteries. The presence of low adsorption energy (−1.693 eV) and significant amount of Bader charge transfer (0.917 e) between Li-ion and C atoms of C80 fulleryne confirms that Li-ion gets chemisorbed on the C80 fulleryne. Remarkably, this cage acts as a storehouse to host 12 Li ions, precisely one for each of its constituent pentagons within the C80 fulleryne structure, bearing a theoretical capacitance of 335 mAhg−1.

Nature of Charge Transfer Effects in Complexes of Dopamine Derivatives Adsorbed on Graphene-Type Nanostructures

Continuing the investigation started for dopamine (DA) and dopamine-o-quinone (DoQ) (see, the light absorption and charge transfer properties of the dopamine zwitterion (called dopamine-semiquinone or DsQ) adsorbed on the graphene nanoparticle surface is investigated using the ground state and linear-response time-dependent density functional theories, considering the ωB97X-D3BJ/def2-TZVPP level of theory. In terms of the strength of molecular adsorption on the surface, the DsQ form has 50% higher binding energy than that found in our previous work for the DA or DoQ cases (−20.24 kcal/mol vs. −30.41 kcal/mol). The results obtained for electronically excited states and UV-Vis absorption spectra show that the photochemical behavior of DsQ is more similar to DA than that observed for DoQ. Of the three systems analyzed, the DsQ-based complex shows the most active charge transfer (CT) phenomenon, both in terms of the number of CT-like states and the amount of charge transferred. Of the first thirty electronically excited states computed for the DsQ case, eleven are purely of the CT type, and nine are mixed CT and localized (or Frenkel) excitations. By varying the adsorption distance between the molecule and the surface vertically, the amount of charge transfer obtained for DA decreases significantly as the distance increases: for DoQ it remains stable, for DsQ there are states for which little change is observed, and for others, there is a significant change. Furthermore, the mechanistic compilation of the electron orbital diagrams of the individual components cannot describe in detail the nature of the excitations inside the complex.

Investigation into geometric configurations and electronic properties of CeO2-supported gold clusters

A detailed understanding of the geometric structure and electronic properties of gold nanoparticles on the ceria surface is crucial for comprehending their unique catalytic activity. Using the first-principles method based on density functional theory, the adsorption of Aux (x = 1–4) clusters on the CeO2(111) surface was studied. It was discovered that the standing configurations of Au2 and Au3, as well as the tetrahedral structure of Au4, are the most stable adsorption structures. The stability of these configurations is jointly determined by the number and strength of Au-Au bonds, the Au-O bonding energy, and the interaction dynamics between the clusters and the substrate. The analysis of Bader charge, difference charge density and density of states suggested that lattice relaxation and electronic localization occur in the reduced Ce3+. The reduced amount and location of Ce3+ are significantly influenced by the position and charge transfer amount of Aux cluster. The adsorption of CO on Au4/CeO2(111) indicated that stronger Au-C bonding energy due to the hybridization of Au-5d and C-2p, thereby enhancing the catalytic activity for CO oxidation reactions.

Electronic properties of InSe/CNT heterojunctions with the modulation of electric field and vacancy defects

We investigate van der Waals (vdW) heterojunctions by combining InSe and zigzag carbon nanotubes (CNT(n,0)) by first-principle calculations. When n ranges from 5 to 7, The heterojunctions show n-type Schottky contact. However, for n of 8, 9, and 11, the heterojunctions still retain the characteristic of semiconductors with bandgaps. The metallized InSe/CNT(10,0) heterojunction has the most amount of charge transfer and the highest tunneling probability. Ohmic contact can be formed in InSe/CNT(n,0) (n = 5–7) heterojunctions under the external electric field. The charge transfer is enhanced and Schottky barrier heights are significantly reduced in heterojunctions with Se vacancy defect. In vacancy defect causes the disappearance of Schottky barrier because of metallization of InSe and more charge transfer than Se vacancy defect in InSe/CNT. Our findings provide a direction for the application of InSe/CNT in tunable nanoelectronic devices.

Electrostatic energy-driven contact electrification mechanism from the ReaxFF molecular dynamics perspective.

Understanding the underlying principles of contact electrification is critical for more efficient triboelectric nanogenerator (TENG) development. Herein, we use ReaxFF molecular dynamics simulations in conjunction with a charge equilibration method to investigate the contact electrification mechanism in polyisoprene (PI), a natural rubber polymer, when it comes into contact with copper (Cu) and polytetrafluoroethylene (PTFE). The simulations reveal that the charge transfer directions in the PI/Cu and PI/PTFE contact models are opposite, and the amount of charge transfer in the former is substantially less than that in the latter, which are consistent with our TENG measurements. Contact electrification is revealed to be a spontaneous process that occurs to lower electrostatic energy, and the electrostatic energy released during contact electrification of PI/PTFE is greater than that of PI/Cu, which can be correlated with the relative strength of triboelectric charging observed for the two systems. A compression simulation of the PI/Cu contact model reveals that the quantity of charge transfer grows exponentially as compressive strain increases. Despite increasing the total energy of the system due to densification and distortion of the polymer structure, the applied deformation results in an energetically more stable electrostatic arrangement. We also find that the incorporation of a carbonaceous material into a polyisoprene matrix causes a faster increase in the amount of charge transfer with compressive strain, which is governed by a steeper electrostatic energy profile. This study provides an alternative perspective on the contact electrification mechanism, which could be beneficial for the development of energy harvesting devices.

SERS activity of silver nanoparticles and silver-modified 2D graphitic carbon nitride towards ciprofloxacin drug

Herein, silver nanoparticles (AgNPs) and silver-loaded graphitic carbon nitride (Ag@g-C3N4) nanocomposites have been synthesized and used as an effective surface-enhanced Raman scattering (SERS) substrates for the detection of low concentrations (10-14 M) of ciprofloxacin (CIP), a commonly bioactive medication used to treat bacterial illnesses. A combined approach of vibrational spectroscopy and density functional theory (DFT) has been developed to understand the possible modes of analyte (CIP) and SERS substrate (AgNPs and Ag@g-C3N4) interactions. Furthermore, it has been noticed that the behavior of drug molecules in terms of SERS response and energetics of interaction changed significantly when interacted with the noble metal AgNPs decorated onto the g-C3N4 framework in comparison to only AgNPs as substrate. The most prominent interaction scenario between AgNPs and CIP is likely to be through the –NH moiety of drug molecule with an interaction energy of −306 kcal/mol. Whereas, the CIP molecules adsorbed onto Ag@g-C3N4 nanocomposite were more flexible with interaction energy of −107 kcal/mol, suggesting a greater association of analyte with the skeletal modes of substrate leading to Raman enhancements in the low wavenumber region i.e. below 600 cm−1. Hence, the Ag@g-C3N4 nanocomposite-based SERS substrates investigated served two distinct spectral ranges, making them complementary of each other in terms of SERS detection of CIP. The characteristics of the computed frontier molecular orbitals indicated a pronounced amount of charge transfer between the drug and the substrate, highlighting the significance of the chemical mechanism of the overall process. These results represent a successful approach to have an extended spectral range that covers lower wavenumber shifts by applying simple and meaningful modifications to the normally utilized noble metal-based nanoparticles, which can lead to more effective and reliable detection of bioactive drugs.

A Molecular Engineered Strategy to Remolding Architecture of RuP2 Nanoclusters for Sustainable Hydrogen Evolution

AbstractTransition metal phosphides (TMPs) are promising hydrogen evolution reaction (HER) electrocatalysts, but the unsatisfying activity and durability at industrial‐scale current densities hinder their application. Downsizing TMPs to nanoclusters can substantially enhance their activity; yet, the high surface free energy tends to initiate agglomeration thereby limiting their service life. Herein, a molecular engineering strategy to synthesize robust sulfur‐doped RuP2 (S‐RuP2) nanoclusters, which can continuously provide ampere‐level current densities of 1.0, 2.0, and 3.0 A cm−2 for at least 480 h with low overpotentials of 55.6 ± 1.0, 90.6 ± 1.2, and 122.8 ± 1.0 mV, respectively, is proposed. In particular, it exhibits a remarkable charge transfer amount (representing a long service life), outperforming all reported alkaline HER electrocatalysts. Remoulding the RuP2 architecture by sulfur atom can significantly lift the d‐band center of Ru and the p‐band center of P, therefore strengthening the adsorption of H2O, H, and OH to reduce the barriers of water dissociation and H migration. The authors‘ research unveils the enormous potential of molecule‐based porous materials for designing high‐performance nano‐structured catalysts.

Computational analysis of C9N4 monolayer as a novel adsorbent for toxic gases

A novel C9N4 nanosheet has been investigated for its potential use as an electrochemical sensor for gaseous pollutants including CO, NO, CO2, HF, and COCl2. The sensing ability of C9N4 is explored theoretically at the ωB97XD/6-311G (d, p) level of theory. The results showed the physisorption of all analytes on the C9N4 surface. The highest interaction energy of −21.96 kcal/mol was observed in COCl2@C9N4. The order of interaction energy was COCl2@C9N4> NO@C9N4 > HF@C9N4 > CO2@C9N4 > CO@C9N4. The Electronic properties of the complexes were examined using EDD (Electron Density Difference), NBO (natural bond orbital), FMO (frontier molecular orbital), and DOS (density of state) analysis. According to NBO analysis, CO2@C9N4 exhibited the maximum amount of charge transfer (−0.026 e−), whereas COCl2@C9N4 exhibited the minimum amount of charge transfer. The adsorption of COCl2 onto the surface of C9N4 resulted in change in the energy gap with a value of −3.12 eV compared to −3.15 eV for C9N4. These findings highlighted the potential of C9N4 as a promising electrochemical sensor for COCl2. The transfer of charges takes place from the analytes to the C9N4, except in HF, where no charge transfer took place. This divergence could be attributed to the strongly bonded electrons between the fluorine and hydrogen atoms of HF. QTAIM and NCI analysis were performed to determine the nature of non-covalent interactions. At 298K, a recovery time of 1.25 × 104 s was calculated for the desorption of COCl2 from the surfaces of C9N4. It was observed that C9N4 shows the highest sensitivity toward COCl2 among all selected analytes.

The O-Defective g-ZnO Sensor for VOC Gases: The Adsorption-Desorption, Electronic, and Sensitivity Properties.

Adsorption-desorption performance, electronic properties, and sensitivity of O-defective g-ZnO (ODZO) gas sensors for volatile organic compounds (VOCs) are calculated using density functional theory and nonequilibrium Green's formalism. The VOCs are CH2O, CH4, C2H4O, CH4O, and C2H6. The intrinsic g-ZnO (IZO) and ODZO exhibit strong adsorption capabilities for C2H4O and CH4O. The IZO (0.118 e) and ODZO (0.059 e), which act as electron donors, exhibit the highest charge transfer to CH2O, indicating a strong interaction. The VOCs adsorption on the IZO and ODZO systems maintain nonmagnetic semiconductor characteristics. Additionally, the introduction of an O-defect causes the adsorption energy and charge transfer amount of ODZO to show an overall decrease, indicating better desorption ability. Notably, the sensitivity results show that the ODZO gas sensors exhibit high sensitivity to CH2O (39.3%), C2H4O (29.0%), and CH4O (19.6%) at a voltage of 2.6 V, consistent with the adsorption-desorption performance and electronic properties.

Synthesis, crystal structure, quantum computational, biological study, molecular docking and molecular dynamic simulations investigations on 2,2′-((1,4-phenylenebis(methylene)) bis(sulfanediyl))dianiline

2,2′-((1,4-phenylenebis(methylene))bis(sulfanediyl))dianiline(PMBD) compound, has been synthesized, and categorized by X-ray, spectroscopic analysis 1H & 13CNMR in solution along with FT-IR and UV-visible analysis. Computational calculations were obtained by density functional. Additionally, 3D and 2D surface analyses were conducted using Hirshfeld surface investigation. For the quantum chemical reckonings, the optimized structure of the PMBD was estimated using the B3LYP/6–311++G(d,p) basis set and compared to the acquired experimental crystal structure parameters, the structure parameters were found comparable. To further validate the NMR results, GIAO method was utilized to evaluation the 1HNMR and 13CNMR shifts, which were then correlate with the experimental spectra. In the analysis of electronic properties, UV–vis absorption was investigated using the TD-DFT/PCM solvent model in various conditions (gas phase, methanol & DMSO). The computed outcomes were correlate with experimental UV–vis spectra, revealing good agreement. The FMO energy data showed that molecule underwent a large amount of charge transfer. The degree of relative electron localization was examined by the ELF, and MEP (Molecular Electrostatic Potential) surface investigation was used to show charge distribution and show reactive zones. Molecular docking was used in biological investigations to find the best ligand-protein connections and possible therapeutic analogues by employing 6 distinct receptors. Overall, this multi-faceted analysis offers insightful information on the molecular characteristics and possible uses of PMBD.

Band alignment engineering of 2D/3D halide perovskite lateral heterostructures.

Two-dimensional (2D)/three-dimensional (3D) halide perovskite heterostructures have been extensively studied for their ability to combine the outstanding long-term stability of 2D perovskites with the superb optoelectronic properties of 3D perovskites. While current studies mostly focus on vertically stacked 2D/3D perovskite heterostructures, a theoretical understanding regarding the optoelectronic properties of 2D/3D perovskite lateral heterostructures is still lacking. Herein, we construct a series of 2D/3D perovskite lateral heterostructures to study their optoelectronic properties and interfacial charge transfer using density functional theory (DFT) calculations. We find that the band alignments of 2D/3D heterostructures can be regulated by varying the quantum-well thickness of 2D perovskites. Moreover, decreasing the 2D component ratio in 2D/3D heterostructures can be favorable to form type-I band alignment, whereas a large component ratio of 2D perovskites tends to form type-II band alignment. We can improve the amount of charge transfer at the 2D/3D perovskite interfaces and the light absorption of 2D perovskites by increasing quantum-well thickness. These present findings can provide a clear designing principle for achieving 3D/2D perovskite lateral heterostructures with tunable optoelectronic properties.

Adsorption and sensing performances of vacancy defects and Cu-embedded GaN/MoTe2 heterostructure for harmful gases: A DFT study

By utilizing density functional theory (DFT), we explore the adsorption and sensing performance of NO, NO2, SO2 and CO on intrinsic GaN/MoTe2 heterostructure, vacancy-defective GaN/MoTe2 heterostructures and Cu-embedded GaN/MoTe2 heterostructures, respectively. The results indicate that the VGa-GaN/MoTe2 heterostructure exhibits higher adsorption energy (yielding more negative values) for all four gases, demonstrating superior adsorption performance compared to the intrinsic system. Similarly, the Cu-GaN/MoTe2 heterostructure also improves the adsorption performance for nitrogen oxides. Meanwhile, the Cu-MoTe2/GaN heterostructure also significantly outperforms the intrinsic systems in terms of adsorption performance for the four harmful gases. Particularly, the Cu-MoTe2/GaN heterostructure has an adsorption energy of −2.22 eV for NO2 and a charge transfer amount of up to 0.72 e, indicating a strong chemical interaction between the adsorption system and gas molecules. Therefore, Cu-MoTe2/GaN is a potential ideal gas adsorption material. This work offers a theoretical foundation for transition metal-doped semiconductor heterostructures for future research.

Electron distribution regulating of nonmetal doped monolayer g-GaN for enhanced electrocatalytic CO2 reduction

Exploring inexpensive electrocatalysts that can efficiently and selectively convert CO2 into hydrocarbon fuels is important to promote carbon neutrality and solve the energy crisis. Current electrocatalysts, such as Cu-based alloys, single-atom catalysts, and dual-atom catalysts, use the d states of metal in the electrocatalytic CO2 reduction reaction. Inspired by this, this work studies CO2 reduction reaction from another approach. Herein, using first principles study, we systematically investigate the prospect of nonmetal (B, C, O and F) doped monolayers g-GaN as electrocatalysts for the CO2 reduction reaction. We found that nonmetal doping can effectively regulate the electron distribution and p-band center of the active center (N site), which can adjust the initial adsorption, activation degree, charge transfer amount of CO2, and promote the formation of intermediates. Interestingly, B and C doped systems have better catalytic activity for CH4, with limiting potentials of −0.61 and −0.53 V, respectively. More importantly, F doped system has higher activity and selectivity for CH3OH production and inhibit competitive HER, with lower limiting potentials of −0.60 V. This study provides a new theoretical basis for the design and screening of electrocatalysts with high activity and product selectivity using nonmetal as the active site.

3D lithiophilic collector coated by amorphous g-C3N4 enabling Ultra-Stable cycling Li metal batteries

Lithium metal batteries (LMB) are thought of the most promising candidates for the next generation of high energy density batteries, but the problems of interface instability and uncontrollable dendrite growth are key constraints to the commercial application. Herein, we constructed an amorphous graphitic carbon nitride (g-C3N4) “outerwear” modified lithiophilic 3D Au/CoO nanoarray matrix (CACM) as a multifunctional dual-layer host, achieving dendrite-free and cycling stabilized Li metal anode. The density functional theory (DFT) calculations show that the reaction between CACM and Li atoms has a strong binding energy and a large amount of charge transfer. The lithiophilic 3D host induces Li metal uniform deposition with a low nucleation barrier within the 3D skeleton. The amorphous g-C3N4 “outerwear” can effectively avoid direct contact between the electrolyte and Li and reduce the irreversible side reaction. Meanwhile, the g-C3N4 layer has abundant Li ion transport channels, which facilitated fast Li+ transfer and modulate the ion concentration over the anode surface. Thus, the half-cell equipped with the CACM electrode has ultra-high cyclic stability, maintaining a CE value of 99.6 % over 230 cycles at 1 mA cm−2 with 1 mAh cm−2. The symmetric-cell can maintain a low overpotential stable run 1300 cycles at 10 mA cm−2. Similarly, the full cell also showed outstanding long-term cycle stability (capacity maintained at 96.3 % after 400 cycles at 1C) and superior rate capability. The in-situ visualization cell test and ex-situ SEM also demonstrated that the multifunctional host inhibits volume expansion and the dendritic growth of Li.

Chemical structure modification of Brazilin-based natural dye with TiO2 nanostructure improves photovoltaic properties for maximum simulated PCE for DSSCs application

Brazilin has been explored as a photosensitizer in dye-sensitized solar cells (DSSCs) owing to its easy extraction, abundance, and environmental friendliness. However, its narrow solar spectrum absorption and weak interaction with the semiconductor hamper its wide application, highlighting the need for developing novel dyes for enhanced DSSC performance. This study reports eight designed dyes (Braz 01 ‒ Braz 02tb) obtained via introducing the π-bridges such as benzene, thiophene, and benzene-thiophene linked to thieno[3,2-b]thiophene, alongside a cyanoacrylic acceptor into the sites of two hydroxyl (OH) groups of brazilin dye. The density functional theory (DFT) and time-dependent density functional theory (TD- DFT) methods were employed to examine the free dyes' photoelectrical, optoelectronic and structural properties. The results show that the absorption spectra of the designed dyes redshifted by 183.22 nm 239.43 nm regarding the brazilin dye. The energy gap was reduced from 5.074 to 2.46 eV. The reorganization energy decreased from 0.951 eV to 0.528 eV, indicating that the designed dyes exhibited better intramolecular charge transfer (ICT). Notably, the electron affinity, electron accepting power, and maximum charge transfer increased from 1.021 3.472 eV, 1.024 8.387 eV and 1.447 4.780, respectively, signifying improved ICT. The exciton binding energy was lowered from 0.591 0.137 eV, implying that all designed dyes possess minimum charge recombination. The amount of charge transfer of the designed dyes (0.286219.051 au) was observed to be greater than brazilin, signifying enhanced ICT. Moreover, the theoretical DSSCs sensitized with designed dyes demonstrated higher PCE than brazilin dye. The greatest PCE of 13.1 % was attained by Braz 01tb dye. Generally, the improved optoelectronic and photovoltaic characteristics observed in all the designed dyes indicate that modifying the hydroxyl group on the brazilin's R1 or R2 location enhances its photoelectrical properties. Therefore, the designed dyes are regarded as superior candidates for utilization as photosensitizers in DSSCs.

Pure and doped graphene as a suitable material for the detection of hazardous gases

The need for highly sensitive toxic gas sensors is significant, and achieving this sensitivity is possible. Researchers have utilized density functional theory (DFT) computations to examine adsorption of different gas molecules (COX2, where X is F, Cl, or Br) over Au-doped and pristine graphene. This investigation aims to determine possibility of employing Au-doped graphene as a basis for gas sensors. Multiple adsorption positions and orientations were examined for each gas molecule. The configuration that exhibited the highest stability was identified, and adsorption energy (Eads) values, considering van der Waals (vdW) interactions, have been computed using NCI analyses. In addition, the electronic properties, including LUMOHOMO orbital density and charge transfer, were analyzed to acquire a deeper understanding of process by which adsorption occurs. Findings indicated that gas molecules under investigation exhibited weak adsorption on pristine graphene, with low Eads values. In contrast, Eads values of every gas molecule on Au-doped graphene displayed varying degrees of increase. Notably, COX2 exhibited a high sensitivity to Au-doped graphene. Furthermore, in the effect of doping Au into graphene, the Eads absorption of COCl2 gas has increased from 0.155 to 1.028 eV. This indicates the strong tendency of Au-doped graphene to interact with gas COCl2 compared to two other COX2 gas species. This strong adsorption can be ascribed to significant substantial charge transfer (CT) between COCl2 and Au-doped graphene and orbital hybridization. The charge transfer amount of the doped states has increased by more than double compared to the pure state. The band gap of Au-doped graphene has decreased from 2.14 to 1.83 eV due to the absorption of gas COCl2, indicating the highest amount of reduction compared to other gases. Moreover, the enhanced electrical conductivity of Au-doped graphene renders it more valuable and sensitive in the context of sensing COX2 gases.

Electronic-rich large conjugated molecules dispersing through ionic liquid solution process for fluorescent detection of iodine gas

Materials containing large conjugated structures have good applications prospects in multiple fields due to their electron-rich properties. Nevertheless, the rigid structures of such materials make them difficult to process, making them difficult to be utilized adequately, which limits further development of their performance potentials. Herein, through ionic liquid solution process (ILSP), the electron-rich and fluorescent properties of pentacene have been successfully liberated to detect iodine vapor. Pentacene can be dissolved in BmimNTf2 to form (Ph)5@BmimNTf2 solution with excellent fluorescence. (Ph)5@BmimNTf2 solution was loaded onto polyamide membranes to prepare composite membrane detectors, which can detect iodine vapors, showing rapid response, portability and low cost. Theoretical calculations indicate a charge-transfer complex is formed between pentacene and iodine. The amount of charge transfer (δQ) between pentacene and iodine monomer molecules can be up to 0.115e. This study provides potential for exploiting the applications of large conjugated materials utilizing ILSP.

From Liouville to Landauer: Electron transport and the bath assumptions made along the way

A generalized quantum master equation approach is introduced to describe electron transfer in molecular junctions that spans both the off-resonant (tunneling) and resonant (hopping) transport regimes. The model builds on prior insights from scattering theory but is not limited to a certain parameter range with regard to the strength of the molecule–electrode coupling. The framework is used to study the simplest case of energy and charge transfer between the molecule and the electrodes for a single site noninteracting Anderson model in the limit of symmetric and asymmetric coupling between the molecule and the electrodes. In the limit of elastic transport, the Landauer result is recovered for the current by invoking a single active electron Ansatz and a binary collision approximation for the memory kernel. Inelastic transport is considered by allowing the excitation of electron–hole pairs in the electrodes in tandem with charge transport. In the case of low bias voltages where the Fermi levels of the electrodes remain below the molecular state, it is shown that the current arises from tunneling and the molecule remains neutral. However, once the threshold is reached for aligning the fermi level of one electrode with the molecular orbital, a small amount of charge transfer occurs with a negligible amount of hopping current. While inelasticity in the current has a minimal impact on the shape of the current–voltage curve in the case of symmetric electrode coupling, the results for a slight asymmetry in coupling demonstrate complete charge transfer and a significant drop in current. These results provide encouraging confirmation that the framework can describe charge transport across a wide range of electrode–molecule coupling and provide a unique perspective for developing new master equation treatments for energy and charge transport in molecular junctions. An extension of this work to account for inelastic scattering from electron–vibrational coupling at the molecule is straightforward and will be the subject of subsequent work.