Net Charge Transfer Research Articles

Enhancing optoelectronic performance of organic solar cells: Alkoxy substitution of central cores and π-bridge units in fully non-fused ring electron acceptors

To systematically elucidate the impact of fluorination and alkoxy modification on the fully non-fused ring electron acceptors (NFREAs) for organic solar cells (OSCs), six fully NFREAs were engineered featuring a benzene core, a selenophene-thiophene unit as the π-bridge, and IC-2F end groups. The derivatives R-D2F and R-D2O were designed by introducing para-substituted fluorine and alkoxy groups onto the central benzene ring of R. Further modifications to the π-bridge of R-D2O, involving variations in the position and number of alkoxy groups, resulted in the derivatives R-DW4O, R-DN4O, and R-D6O. Molecular Dynamics (MD), Density Functional Theory (DFT), and Time-Dependent Density Functional Theory (TD-DFT) simulations were used to predict the optoelectronic properties of these compounds. A comprehensive analysis was conducted on aspects including intramolecular non-covalent interactions, transition density matrix (TDM), electron-hole distributions, charge density difference (CDD), and inter-fragment charge transfer (IFCT). Additionally, the electron transfer rate constants (Ke) and electron mobility (μe) of dimeric structures were calculated to better understand the electronic transmission behavior of these acceptor molecules. The results show that alkoxy substitution on the central core, rather than fluorine substitution, enhances planarity, strengthens intermolecular interactions, reduces the energy gap, induces a red shift in the absorption spectrum, and improves electron excitation efficiency and net charge transfer. The addition of alkoxy groups to the π-bridge further promotes non-covalent interactions, enhancing light absorption and increasing light harvesting efficiency (LHE). Among the derivatives, R-D6O, which features cooperative alkoxy substitution on both the thiophene and selenophene units, exhibits the highest electron mobility, making it a promising candidate for OSC applications. These findings provide valuable insights into the design of high-performance fully NFREAs for OSCs.

Inter- and Intra-Molecular Charge Redistributions in H-Bonded Cyanuric Acid*Melamine (CA*M) Networks: Insight From Core Level Spectroscopy and Natural Bond Orbital Analysis.

In this work, we elucidate the electronic charge redistributions that occur within the cyanuric acid (CA) and melamine (M) molecules upon formation of the triple H-bond between the imide group of CA and the diaminopyridine group of M. To achieve this, we investigated 2D H-bonded assemblies of M, CA and CA*M grown on the Au(111) surface, using X-ray photoemission (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopies. Compared to the homomolecular networks, the spectra of the mixed sample reveal core level shifts in opposite directions for CA and M, indicating a nearly complementary charge accumulation on the CA molecule and a charge depletion on the M molecule. These findings were further confirmed by theoretical simulation of the ionization potentials (IPs), which were computed using unsupported models of the H-bonded networks. A natural bond orbital (NBO) analysis performed on the three systems helped to rationalize the net charge transfer form M to CA. Finally, we observed that intramolecular interactions (electron delocalization effects) contribute progressively to the charge redistributions inside the two molecules when going from the homomolecular to the heteromolecular networks.

Interfacial Engineering of β‐Ketoenamine‐Based COFs/Urea‐Linked Perylene Diimide for Overall Photosynthesis of H2O2 in Seawater

AbstractHigh‐efficiently non‐sacrificial H2O2 production is challenging due to the sluggish kinetics of ORR and WOR and severe electron‐hole recombination. Via interfacial engineering, a series of non‐metal photocatalysts are rationally designed and constructed, covalently bonded TpDT‐COF (TP) and urea‐PDI (UP), to achieve high non‐sacrificially photocatalytic H2O2 production in seawater. Experimental and theoretical analysis has revealed that an interfacial electric field is formed between covalently bonded TP and UP, which provides an internal driving force to enhance the electron‐hole separation. Further mechanistic studies reveal that the H2O2 production follows a simultaneous two‐step 2e− ORR and 4e− OER route. Moreover, the activity toward OER of the active center at the UP is significantly promoted due to a net charge transfer from UP to TP after covalently bonding. As a result, a high non‐sacrificial H2O2 production rate of 3846 µmol gh−1 in seawater is achieved. Furthermore, a 4.7 mM H2O2 is obtained after a 13 h‐continuous photocatalytic reaction, which can be directly used to purify dye and phenol contaminated water. Notably, the strategy of creating interfacial electric field coupled with desired charge transfer provides a universal approach for non‐sacrificial photosynthesis by enhancing the electron‐hole separation and activity of catalytic centers simultaneously.

Enhancing hydrogen storage efficiency: Computational insights into scandium-decorated 2D polyaramid

This study explores hydrogen storage in 2D polyaramid (2DPA) and its enhancement via scandium decoration for onboard storage in fuel cell vehicles. Sc decoration in 2DPA is accompanied by a net 1.6 e charge transfer from Sc to 2DPA. Hydrogen binding in 2DPA + Sc proceeds with a net charge transfer of 0.32 e from Sc towards H2. 2DPA + Sc demonstrates a maximum hydrogen loading capacity of 8.589 wt% with an average adsorption energy of −0.376 eV/H2. These findings meet the stipulated criteria by the US Department of Energy for solid-state hydrogen storage in light-duty vehicles. Feasibility studies were conducted considering practical limitations in transition metal-modified carbon nanomaterials, including Sc-Sc clustering tendencies, stability, and hydrogen desorption behavior via ab initio molecular dynamics simulations, phonon dispersion, and diffusion studies. The highest barrier height for hydrogen desorption from 2DPA + Sc is 0.48 eV, and desorption is predicted to occur at 412 K (5 bar) indicating possibility of room temperature and reversible hydrogen storage. Our findings indicate that 2DPA + Sc is a promising hydrogen storage substrate material and should be explored in experimental trials.

Harnessing MBene termination for superior anode interfaces in Li/Ca-ion batteries

The elevation of two-dimensional (2D) transition metal borides, specifically MBenes, as anode materials for lithium-ion batteries (LIBs) and calcium-ion batteries (CIBs) can be achieved through strategic functionalization with appropriate groups. Utilizing a first-principles approach, we conducted an in-depth investigation into the electrochemical properties of chlorine-terminated V2B (V2BCl2) as a candidate anode material for LIBs and CIBs. V2BCl2 exhibits metallic behavior, as demonstrated by band structure analysis, which endows it with exceptional conductivity due to the free electron surface of the system, thereby embodying ideal anode characteristics. The dynamic and thermal stability of the system was assessed through comprehensive phonon dispersion analyses and ab-initio molecular dynamics (AIMD) calculations. High net charge transfer rates of Li/Ca ions towards the monolayer, augmented electron localization function (ELF) near system atoms, and the presence of ionic bonds between Ca/Li and the V2BCl2 monolayer contribute to the enhanced conductivity observed in these anode systems. This is corroborated by metrics such as the projected crystal orbital Hamiltonian population (-pCOHP), low diffusion energy barriers (< 0.35 eV) facilitating rapid charging mechanisms, and low open circuit voltages (< 0.32 V) ensuring robust battery performance stability. Furthermore, V2BCl2 exhibits notable specific storage capacities of 875.67 mAh g−1 for Ca ions and 1167.75 mAh g−1 for Li ions, surpassing the benchmarks set by recent MBene systems. These promising results strongly advocate for V2BCl2 as a viable candidate for anode material in both LIB and CIB applications, highlighting its potential significance in advancing battery technology.

The germanides ScTGe2 (T = Fe, Co, Ru, Rh) – crystal chemistry, 45Sc solid-state NMR and 57Fe Mössbauer spectroscopy

Abstract The TiMnSi2-type (space group Pbam) germanides ScTGe2 (T = Fe, Co, Ru, Rh) were synthesized from the elements by arc-melting. Single crystals were grown by annealing sequences of the arc-melted buttons in an induction furnace. The structures of ScFeGe2, ScRuGe2 and ScRhGe2 were refined from single-crystal X-ray diffraction data. In ScRuGe2, the ruthenium atoms have distorted octahedral germanium coordination (242–268 pm Ru–Ge). Three trans-face-sharing octahedra form a sub-unit which is condensed via common edges in c direction and connected via common corners with four adjacent blocks, forming a three-dimensional [RuGe2 type] substructure. The two crystallographically independent scandium sites have coordination numbers 15 (Sc1@Ge8Ru4Sc3) and 17 (Sc2@Ge7Ru6Sc4). Electronic band structure calculations for ScCoGe2 and ScRuGe2 show a net charge transfer from the scandium to the transition metal and germanium atoms, leading to a description with polyanionic networks Sc δ+[TGe2]δ−. The two crystallographically independent Sc sites are easily distinguishable by 45Sc magic-angle spinning (MAS)-NMR spectroscopy. Isotropic chemical shift values and nuclear electric quadrupolar interaction parameters were deduced from an analysis of the triple-quantum (TQ)-MAS NMR spectra. The electric field gradient parameters deduced from these experiments are in good agreement with quantum-chemical calculations using the Wien2k code. Likewise, the two crystallographically independent iron sites in ScFeGe2 could be discriminated in the 57Fe Mößbauer spectra through their isomer shifts and quadrupole splitting parameters: δ = 0.369(1) mm s−1 and ∆E Q = 0.232(2) mm s−1 for Fe1 and δ = 0.375(2) mm s−1 and ∆E Q = 0.435(4) mm s−1 for Fe2 (data at T = 78 K).

In silico investigation on sensing of tyramine by boron and silicon doped C60 fullerenes

The present communication deals with the adsorption of tyramine neurotransmitter over the surface of pristine, Boron (B) and Silicon (Si) doped fullerenes. Density functional theory (DFT) calculations have been used to investigate tyramine adsorption on the surface of fullerenes in terms of stability, shape, work function, electronic characteristics, and density of state spectra. The most favourable adsorption configurations for tyramine have been computed to have adsorption energies of − 1.486, − 30.889, and − 31.166 kcal/mol, respectively whereas for the rest three configurations, it has been computed to be − 0.991, − 6.999, and − 8.796 kcal/mol, respectively. The band gaps for all six configurations are computed to be 2.68, 2.67, 2.06, 2.17, 2.07, and 2.14 eV, respectively. The band gap of pristine, B and Si doped fullerenes shows changes in their band gaps after adsorption of tyramine neurotransmitters. However, the change in band gaps reveals more in B doped fullerene rather than pristine and Si doped fullerenes. The change in band gaps of B and Si doped fullerenes leads a change in the electrical conductivity which helps to detect tyramine. Furthermore, natural bond orbital (NBO) computations demonstrated a net charge transfer of 0.006, 0.394, and 0.257e from tynamine to pristine, B and Si doped fullerenes.

Intercalation of Lithium Atom/Ion in carbon, Silicon and Germanium Nanotubes

In this paper, we have studied the impact of Li atom/ion intercalation in C, Si and Ge nanotubes. The bond lengths for the optimized structures of the Li atoms/ions intercalation are similar and consistent with the bond lengths of pristine nanotubes. Based on Mulliken population and charge density analysis,there is a net transfer of charge from Lithium atoms to nanotube atoms. However, it is opposite in case of ion intercalation. The intercalation of Li atom/ion alters the electronic structure of the SWNTs, resulting in a shift from semiconducting to metallic. Our study also reveals that the conductance is 5G 0 for GeNT on Li atom/ion intercalation, which is 2G 0 for pristine GeNT. Due to their enhanced conductance as compared to pristine nanotubes, Li atom/ion intercalated systems can also be expected as materials for nano scale electronic devices, perfect for ballistic transport.

Ab initio calculations of through-space and through-bond charge-transfer properties of interacting Janus-like PbSe and CdSe quantum dot heterostructures

Heterostructure quantum dots (QDs) are composed of two QD nanocrystals (NCs) conjoined at an interface. They are useful in applications such as photovoltaic solar cells. The properties of the interface between the NCs determine the efficiency of electron–hole recombination rates and charge transfer. Therefore, a fundamental understanding of how this interface works between the two materials is useful. To contribute to this understanding, we simulated two isolated heterostructure QD models with Janus-like geometry composed of Cd33Se33 + Pb68Se68 NCs. The first Janus-like model has a bond connection between the two NCs and is approximately 16 × 17 × 29 Å3 in size. The second model has a through-space connection between the NCs and is approximately 16 × 17 × 31 Å3. We use density functional theory to simulate the ground state properties of these models. Nonadiabatic on-the-fly couplings calculations were then used to construct the Redfield Tensor, which described the excited state dynamics due to nonradiative relaxation. From our results, we identified a qualitative trend which shows that having a bond connecting the two NCs reduces hole relaxation time. We also identified for a sample of electron–hole excitations pairs that the through-bond model allows for a net positive or negative numerical net charge transfer, depending on the excitation pair.

Cementite-type Y3Ru

Abstract Single crystals of Y3Ru were obtained as a side product during phase analytical studies of yttrium-rich compounds in the system Y–Ru–Zn. The structure of Y3Ru was refined from single-crystal X-ray diffractometer data: Fe3C type, Pnma, a = 732.51(7), b = 925.61(8), c = 633.66(10) pm, wR = 0.0639, 811 F 2 values, 23 variables. The ruthenium atoms have coordination number 9 in form of a strongly distorted tricapped trigonal yttrium prism with Ru–Y distances ranging from 275–391 pm. The second substructure concerns empty Y6 octahedra (d(Y–Y) = 344–396 pm). Electronic structure calculations show a net charge transfer from yttrium to ruthenium and underpin the essentially covalent Y–Ru bonding. A phase-pure sample of Y3Ru was synthesized from the elements by arc-melting. Temperature-dependent magnetic susceptibility studies of this sample reveal Pauli paramagnetism (3.6(1) × 10−5 emu mol−1 at T = 300 K).

Flow-Electrode Microbial Electrosynthesis for Increasing Production Rates and Lowering Energy Consumption

• Scalable flow-electrode MES reactor was constructed for CO 2 utilization. • Powder activated carbon amendment doubled acetate production rate. • Flow-electrode decreased the electroosmosis rate and charge transfer resistance. • Flow-electrode increased the expressive abundance of genes for electron transfer. • WLP and rTCA were the complete pathways for carbon fixing. The development of microbial electrosynthesis (MES) for renewable electricity-driven bioutilization of CO 2 has recently attracted considerable interest due to its ability to synthesize chemicals with the transition towards a circular carbon economy. However, the increase of acetate production and the decrease of energy consumption of MES using an advanced reactor design have received less attention. In this study, the total acetate production rate using novel flow-electrode MES reactors ((16 ± 1) g·m −2 ·d −1 ) was double that using reactors without powder activated carbon (PAC) amendment ((8 ± 3) g·m −2 ·d −1 ). The flow-electrode MES reactors had a Coulombic efficiency of 43.5% ± 3.1%, an energy consumption of (0.020 ± 0.005) kWh·g −1 , and an energy efficiency of 18.7% ± 1.3% during acetate production. The flow-electrode with PAC amendment could decrease the net water flux and charge transfer resistance, while had little impact on the cell voltage, rheological behavior, and acetate adsorption. In the flow-electrode MES reactors, the expression of genes involving in energy production and conversion were increased, and the increase of acetate production was found correlated with the increased abundance of Acetobacterium. The Wood–Ljungdahl pathway (WLP) and reductive citric acid cycle (rTCA) were found to be the complete pathways responsible for carbon fixation. The concentrations of acetate in the stacked flow-electrode MES reached 7.0 g·L −1 . This study presents a new approach for the construction of scalable MES reactors with high-performance chemical generation and CO 2 utilization.

Chemisorption and physisorption studies of carbonyl fluoride and carbon disulfide on C19 X (X = Zn, Co and Sc) nanocage by DFT-based calculation

In this study, we used the DFT calculations and the B3LYP functional to examine the adsorption of the CS2 and COF2 molecules on the surface of the clusters C20 and C19X (X = Zn, Co, Sc). The results have been investigated by the net charge transfer, frontier orbitals, the binding energy, electrical and thermodynamic properties. Although CS2 and COF2 complexes on free C20 nanocages showed slightly binding energies (−0.163 eV), doping them with (Zn, Co and Sc) transition metal atoms improved the binding energy because the substitution of carbon atoms with metal atoms (Zn, Co, Sc), C19X (X = Zn, Co, Sc) nanocages were found to be more stable. Adsorption of COF2 on C19Sc produced the best binding energy (−2.667 eV). Also, natural bond orbital (NBO) analysis showed that the best charge transfer was (−0.602e) which was related to the formation of COF2−C19Sc complex. Furthermore, the least HOMO, LUMO energy gap between free nanocages (C20, C19Zn, C19Co, C19Sc) is 5.36 eV (C19Co and C19Sc). The thermodynamic analyses indicated that all of the adsorption processes examined were exothermic because of the negative enthalpy.

Excimer Energies.

A multistate energy decomposition analysis (MS-EDA) method is introduced for excimers using density functional theory. Although EDA has been widely applied to intermolecular interactions in the ground state, few methods are currently available for excited-state complexes. Here, the total energy of an excimer state is separated into exciton excitation energy ΔEEx(|ΨX·ΨY⟩*), resulting from the state interaction between locally excited monomer states |ΨX*·ΨY⟩ and |ΨX·ΨY*⟩ , a superexchange stabilization energy ΔESE, originating from the mutual charge transfer between two monomers |ΨX+·ΨY⟩ and |ΨX-·ΨY+⟩ , and an orbital-and-configuration delocalization term ΔEOCD due to the expansion of configuration space and block-localized orbitals to the fully delocalized dimer system. Although there is no net charge transfer in symmetric excimer cases, the resonance of charge-transfer states is critical to stabilizing the excimer. The monomer localized excited and charge-transfer states are variationally optimized, forming a minimal active space for nonorthogonal state interaction (NOSI) calculations in multistate density functional theory to yield the intermediate states for energy analysis. The present MS-EDA method focuses on properties unique to excited states, providing insights into exciton coupling, superexchange and delocalization energies. MS-EDA is illustrated on the acetone and pentacene excimer systems; three configurations of the latter case are examined, including the optimized excimer, a stacked configuration of two pentacene molecules and the fishbone orientation. It is found that excited-state energy splitting is strongly dependent on the relative energies of the monomer excited states and the phase-matching of the monomer wave functions.

Cation functional group effect on SO2 absorption in amino acid ionic liquids.

Introduction: The effect of the functional group of the cation on SO2 acidic gas absorption by some designed amino acid ionic liquids (AAILs) was studied. Methods: An isolated pair of glycinate anion and pristine imidazolium-based cation, as well as decorated cation functionalized by hydroxyl (OH), amine (NH2), carboxylic acid (COOH), methoxy (OCH3), and acetate (CH3COO) groups, were structurally optimized by density functional theory (DFT) using split-valence triple-zeta Pople basis set. Results and Discussion: The binding and Gibbs free energy (ΔGint) values of SO2 absorption show the AAIL functionalized by the COOH group is the most thermodynamically favorable green solvent and this functional group experiences the closest distance between anion and captured SO2 and vice versa in the case of cation … SO2 which may be the main reason for being the best absorbent; in addition, the highest net charge-transfer amount of SO2 is observed. Comparing the non-covalent interaction of the systems demonstrates that the strongest hydrogen bond between captured gas and anion, as well as π-hole, and van der Waals (vdW) interaction play critical roles in gas absorption; besides, the COOH functional group decreases the steric effect while the CH3COO functional group significantly increases steric effect after absorption that declines the hydrogen bond.

Ternary magnesium gallides – synthesis, crystal chemistry and properties of CaMgGa, SrMgGa, BaMgGa and YbMgGa

AbstractThe gallides CaMgGa, SrMgGa, BaMgGa and YbMgGa were synthesized from the elements in sealed tantalum ampoules in muffle furnaces. The phase purity of the samples was checked by powder X‐ray diffraction. CaMgGa and YbMgGa crystallize with the ZrNiAl type structure, space group P 2m, whereas SrMgGa and BaMgGa adopt an ordering variant of the Cu2Sb/PbFCl type, space group P4/nmm. The structures of SrMg0.884(7)Ga1.116(7) (a=459.23(9), c=792.43(12) pm, wR2=0.0371, 226 F2 values, 11 variables) and YbMgGa (a=774.55(7), c=411.95(4) pm, wR2=0.0329, 342 F2 values, 15 variables) were refined from single crystal X‐ray diffractometer data. Refinement of the occupancy parameters indicated a small degree of Mg/Ga mixing on the 2a site for the strontium compound. The [MgGa] substructures in both compounds are composed of condensed Mg@Ga4 tetrahedra with 4×287 pm Mg−Ga in SrMg0.884Ga1.116 vs 2×282 and 2×296 pm in YbMgGa. The SrMgGa structure has a stacking of layers of edge‐sharing Mg@Ga4 and Sr4 tetrahedra. Electronic structure calculations indicate a net charge transfer from strontium and magnesium to gallium. YbMgGa completes the series of REMgGa gallides. Temperature dependent magnetic susceptibility studies reveal weak Pauli paramagnetism, confirming divalent ytterbium.

The first-principles study of structural and electronic properties of two-dimensional SiC/GeC lateral polar heterostructures

Two-dimensional (2D) lateral polar heterostructures, constructed by seamlessly stitching 2D polar materials, exhibit unique properties triggered by the in-plane charge transfer between different elements in each domain. Our first-principles study of 2D SiC/GeC lateral polar heterostructures has unraveled their interesting characteristics. The local strain induced by a lattice mismatch leads to an artificial uniaxial strain along the interface. The synergistic effect of such uniaxial strain, the microstructure of interface, and the width of domains modulates the feature of the bandgap with an indirect bandgap nature in armchair lateral heterostructures and a direct bandgap nature in zigzag lateral heterostructures. The bandgap monotonically decreases with increasing the width of domains, showing its tunability. Furthermore, the valence band maximum is found to be mainly contributed from C-2p orbitals located at both GeC and SiC domains, and the conduction band minimum is mainly contributed from Ge-4p orbitals located at the GeC domain, implying that most excited electrons prefer to stay at the GeC domain of the SiC/GeC lateral polar heterostructures. Interestingly, a net charge transfer from the SiC domain to the GeC domain was found, resulting in a spontaneous lateral p–n junction, and there is a net charge redistribution at the interfacial region leading to a built-in electric field which is expected to reduce the carrier recombination losses, implying the promising application for visible light photocatalyst, photovoltaics, and water splitting to achieve clean and renewable energy.

A DFT study of gas molecules adsorption on intrinsic and Cu-doped graphene gas nanosensors

In this study, first-principles calculations are performed to investigate the sensitivity of intrinsic graphene sheet (GS) and Cu-doped graphene sheet (Cu-GS) gas nanosensors for adsorbing CO, H2, and H2S gas molecules using QUANTUM ESPRESSO package. The density of states (DOS), net charge transfer, adsorption energy, partial density of states (PDOS), and the most stable adsorption configuration of these molecules on GS and Cu-GS are studied. The results show the weak physical adsorption of the three gas molecules on GS. The strength of interaction between the Cu-GS system and adsorbed gas molecules is higher due to the Cu doping. It is expected that the significant increase in charge transfer and adsorption energy leads to fundamental improvement in the electrical conductivity of the Cu-GS system. The results indicate that the introduction of Cu impurity can improve the gas sensing properties of graphene-based gas nanosensors. Therefore, Cu-GS is more appropriate for detecting gas molecules compared to pure GS. The results in this study are useful for developing the design of gas nanosensors.

New Insight of Fe Valence State Change Using Leaves: A Combined Experimental and Theoretical Study

Fe2+ is of considerable importance in plant growth and crop production. However, most Fe elements in nature favor existing in the trivalent state, which often causes the deficiency of Fe2+ in plants. Here, we report the Fe valence state change from Fe3+ to Fe2+ by using leaves. This valence state change was confirmed by x-ray photoelectron spectroscopy in Fe-Cl@leaves. Fourier transform infrared and ultraviolet-visible spectroscopy demonstrated that aromatic ring groups were included in leaves, and cation-π interactions between Fe cations and the components containing aromatic rings in leaves were measured. Further, density functional theory calculations revealed that the most stable adsorption site for hydrated Fe3+ cation was the region where hydroxyl groups and aromatic rings coexist. Moreover, molecular orbital and charge decomposition analysis revealed that the aromatic rings took the major part (59%) of the whole net charge transfer between leaves and Fe cations. This work provides a high-efficiency and eco-friendly way to transform the Fe valence state from Fe3+ to Fe2+, and affords a new insight into the valance change between plant organisms with cations.

Electrochemical promotion of catalysis

The Electrochemical Promotion of Catalysis (EPOC) or Non-Faradaic Electrochemical Promotion of Catalysis (NEMCA effect) is a phenomenon observed as a reversible change in catalytic rate (i.e. no net charge transfer rate) of a chemical reaction occurring on a catalyst film (or supported dispersed catalyst) deposited on an ionically conducting or mixed electronically-ionically conducting solid electrolyte support upon the application of an electrical potential between the catalyst and a second conductive film deposited on the solid electrolyte support.

Synergistic effects of zeolite and oxygen vacancies in SnO2 for formaldehyde sensing: Molecular simulation insights & experimental verification

Computational methods and experimental validation were used and corroborated to investigate the formaldehyde sensing mechanism of SnO2/Na-ZSM-5 zeolite composite. The structure-transport properties of fo€rmaldehyde and acetone gas molecules in Na-ZSM-5 were investigated with molecular simulation (MS) and Monte Carlo (MC) techniques. Formaldehyde molecules “co-adsorbed” with water at the polar center of the zeolite framework, some molecules permeated through the zeolite and adsorbed on the surface with hydroxyl groups, enriching the local concentration of formaldehyde. Density functional theory (DFT) calculation showed that formaldehyde has greater adsorption energy and net charge transfer on the zeolite compared with acetone. The oxygen vacancies of SnO2 in the composite enhanced the sensitivity to formaldehyde. The synergistic effects of the zeolite and the oxygen vacancies of SnO2 significantly enhanced formaldehyde sensitivity and selectivity for the sensor. The experimental results were in good agreement with the computational simulation conclusions.