eV Adsorption Energy Research Articles

Exploring carbon-based Cu-ZnO catalyst and substitutes for enhanced selective methanol production from CO2: An integrated experimental and computational study

Methanol, produced through the hydrogenation of carbon dioxide, is an essential intermediate compound that plays a crucial function in the production of various organic chemicals. Enhancing the design of copper-containing catalysts for the transformation of CO2 to methanol is a popular strategy in scientific literature, although challenges persist in advancing the efficiency of carbon dioxide transformation and the selectivity of methanol production. This research aims at creating CuZnO-M/rGO (M = Mg, Mn, and Cr) catalysts using an efficient method for selectively converting CO2 to methanol. By optimizing the operational parameters of this system, methanol productivity and CO2 conversion efficiency are enhanced. Under optimal conditions, a CO2 conversion rate of 23.5%, methanol selectivity of 90%, and a space-time yield of 0.47 gMeOH.gcat−1.h−1 were achieved with the CuZnO-MgO (5)/rGO catalyst. These levels were maintained over a 100-h period, demonstrating the stability of the catalyst system. These findings are highly consistent with the density functional theory (DFT) calculations, revealing that the CuZnO-MgO (5)/rGO catalyst possesses a −0.35 eV adsorption energy for CO2 and a favorable reaction pathway with the overpotential of 1.16 V towards methanol production emphasizing the high conversion and selectivity obtained.

Unveiling siliborophene's potential as an anode material for advancing Li ion batteries: DFT and ab-initio molecular dynamics

A favorable anodic candidate with significant potential is currently in high demand for Lithium-ion batteries. The χ3 borophene, a two-dimensional material, shows potential as an anode in Li-ion batteries. However, its original structure requires improvement to enhance its Li diffusivity and specific capacity. This research investigates the modification of χ3 borophene by silicon atoms, resulting in a new structure called siliborophene, using density functional theory. Ab-initio molecular dynamics simulations confirm the stability of siliborophene structure at room temperature. The Siχ3 structure hosts adsorption sites for the Li atom, and after exploring various positions, the most favorable configuration exhibits an adsorption energy of −1.33 eV. The siliborophene surface can adsorbed up to 13 Li atoms but according to the further analyses the results of open-circuit voltage suggest that the siliborophene structure can store 10 Li atoms, so Li10Siχ3 structure is considered as the structure with maximum adsorption capacity. The interaction between the surface and Li atoms is stronger in this configuration, with −1.10 eV adsorption energy which yields a maximum specific capacity of 1291 mAh/g. Analysis of the partial density of states and band structure reveals metallic characteristics of the surface during lithiation. Furthermore, using the CI-NEB approach, the barrier activation energy for Li diffusion was calculated, showing exceptionally low values at 0.32 eV, enabling rapid Li diffusion on the surface. These findings indicate that siliborophene holds promise as a potential anode material for lithium-ion batteries.

Achieving arbitrary CO2 adsorption energy on χ3 borophene surface by applying electric field or strain: DFT and RSM approaches

The study of χ3 borophene modification was considered finding an applicable technique to achieve more efficient approaches in CO2 capturing. In the framework of density functional theory (DFT), two surface modification methods were described, external electric field or strain application on χ3 borophene, and the effect of them was investigated on CO2 adsorption. All these methods affected the deformation charge density of the surface, which led to an increase in the CO2 binding energy, in the studied range. The turning point in CO2 capturing and structural changes appeared by applying an electric field of −0.030 a.u. strength with −0.48 eV adsorption energy. The uniaxial and biaxial compressive strain resulted in proper adsorption energy of −0.73 to −0.85 eV, although it caused a significant change in the planar structure of the surface. The structural and electronic properties, in addition to the charge density difference analysis, confirmed the chemisorption of CO2 on modified surfaces. Lastly, for the first time, the response surface methodology in the DFT framework was used to evaluate the simultaneous effect of applying an external electric field and strain as well as charge injection on CO2 adsorption. The generated quadratic equation predicts the CO2 adsorption energy with high accuracy as a function of the modification parameters. This result would be very helpful in adjusting the modification parameters to achieve the desired CO2 adsorption energy with lower experimental costs, where the χ3 surface is used for a special application such as CO2 removal or sensing.

Pristine and metal decorated biphenylene monolayer for enhanced adsorption of nitrobenzene: A DFT approach

This work reports a first-principles density functional theory (DFT) investigation of nitrobenzene (NB) sensing in pristine and metal-decorated biphenylene (p-BP and m-BP, m = Sc, Cu, Li, and Pd) 2D monolayer. Though the proposed p-BP monolayer displayed excellent adsorption of NB molecule compared to other reported 2D materials, it gets physisorbed on the p-BP surface with −0.621 eV adsorption energy. The metal decoration drastically reformed the NB adsorption capacity of BP and induced remarkable changes to the electronic properties. The ab-initio molecular dynamics simulations were employed to analyze the room temperature structural integrity of the m-BP-based NB sensor. Among all the systems considered, the Pd decorated BP monolayer came out as the potential NB sensor with a reasonable adsorption energy of −1.42 eV, charge transfer of 0.38 e, the recovery time of 0.92 s at 598 K, and structural solidity at ambient temperature. The higher diffusion barrier of 0.99 eV confirmed that the Pd dopant does not show the tendency to form clusters. The study demonstrates that the Pd decorated BP is highly apposite for NB sensing and is beneficial for practical application. Our study opens a new avenue for designing and developing efficient biomolecule sensors.

Stabilization of ruthenium nanoparticles over NiV-LDH surface for enhanced electrochemical water splitting: an oxygen vacancy approach

Oxygen vacancy assisted stabilization of Ru@NiV-LDH was achieved via wet chemical methods. Ru@NiV-LDH showed an excellent water splitting activity. DFT analysis confirmed the stabilization Ru NPs over the LDH surface by 3.8 ± 0.5 eV adsorption energy.

Sensitive SO2 gas sensor utilizing Pt-doped graphene nanoribbon: First principles investigation

The objective of this work is to seek a highly sensitive gas sensor for the detection of sulfur dioxide (SO2) by investigating the impacts of passivation as well as metal doping of armchair-edge graphene nanoribbon (AGNR) on the adsorption capacity. Herein, two AGNR based sensor materials for SO2 are passivated with hydrogen and nitrogen (AGNRH and AGNRN) then investigated theoretically using density functional theory (DFT). The results demonstrate that AGNRH is more sensitive to SO2 gas than AGNRN with −0.532 eV adsorption energy (Ead) and 0.05 e charge transfer (ΔQ). Furthermore, two more sensor materials are examined via doping AGNRH and AGNRN with platinum: Pt-AGNRH and Pt-AGNRN. Interestingly, the adsorption energies and charge transfer increased remarkably to −6.327 eV (almost 12 times the non-doped case) and 0.373 e, respectively, for the case of the SO2/Pt-AGNRH system. The same trend is observed as well for the case of SO2/Pt-AGNRN. The significant improvement of the adsorption parameters specifies that Pt doping has a considerable impact on enhancing the sensing performance of passivated AGNR toward the detection of SO2 gas.

A thorough study on the F-decoration of χ3 borophene and enhancement of anodic performance of Lithium-ion batteries

χ3 borophene is a promising 2D anode material in Lithium-ion batteries, but its pristine structure needs to be improved for increasing its specific capacity and Li diffusivity. For this purpose, the decoration of χ3 with the Fluorine atom was investigated using the density functional theory. Two F-decorated χ3 configurations (Fχ3-A and Fχ3-B) with very close energy and good kinetic stability were identified for the Li storage. Li atoms were gradually loaded on both configurations and the results showed a maximum specific capacity of 1396 mAh/g for the Fχ3-B structure which thermodynamically is a slightly lower stable configuration. The interaction of the Li atom with the surface is stronger in this configuration and resulting in −1.75 eV adsorption energy. The PDOS and band structure analysis showed a good metallic characteristic of the surface during lithiation process. The Li diffusion barrier in this structure is extremely low, 0.21 eV, which enables very fast Li diffusion on the surface. Also, this study demonstrated the importance of considering the different configurations resulting from decorating a structure, with proper thermodynamic and kinetic stability, in the computational investigation. As in this study, for F-decorated χ3 borophene, the configuration with lower stability and symmetry showed better results in all storage parameters of Li atoms.

Response of inorganic Al12N12 nano-cage toward nitrosyl hydride: A computational study

The geometrical and electronic structures of adsorption of HNO on Al12N12 nanocage have been examined utilizing DFT computations by means of a (B3LYP-D) function with 6-31G* basis set. It was observed that HNO prefers to be adsorbed on the cage oxygen atom with −0.70 eV adsorption energy. This process of adsorption remarkably decreases the HOMO-LUMO gap (Eg) of the cage from 3.91 to 1.41 eV. The time-dependent density functional theory (TDDFT) indicates a high intensity peak in 390.29 nm in the steadiest complexes of HNO with Al12N12. The alteration in electronic attributes of the Al12N12 nanocage on adsorption of HNO is enough to consider it a potential sensor for the detection of HNO. The Al12N12 nanocage is Ф-type sensor and electronic sensor for HNO.

Molecular and dissociative adsorption of tetrachlorodibenzodioxin on M-doped graphenes (M = B, Al, N, P): pure DFT and DFT + VdW calculations.

Tetrachlorodibenzodioxin (TCDD) is one of the most famous dioxin families that is hazardous to humans and the environment. Designing cheap and novel catalysts for its detecting and removing is an essential need for the environment. In this work, DFT + VdW is used to investigate the potentiality of proposed catalysts in adsorbing and dissociating TCDD. P-type and N-type charge carrier effects on the adsorption process are modeled by doping of B/Al and N/P atoms in the graphene. Al-doped graphene, with - 1.27eV adsorption energy, has the highest possibility to adsorb TCDD. P-type dopants have higher interactions with TCDD in comparing with N-type dopants. Introducing positive and negative charges on the studied complexes shows that in all complexes, the driving force of complexation is π-π stacking except for the Al-doped graphene. Dissociative adsorption studies show that unlike literature data, chlorine atoms on the surface of studied catalysts are not dissociated from TCDD, and instead, C-O bonds in TCDD are dissociated symmetrically and asymmetrically. Data show that Al-doped graphene is the best catalyst for symmetrical dissociation, and pure graphene is the best one for asymmetrical dissociation of TCDD.

Density functional calculations of organic pollutants adsorbed on Hittorf's violet phosphorene

Abstract Hittorf's violet phosphorene with large specific surface area and high hole mobility is a potential candidate for gas sensing. Here, a case about adsorption behavior of organic chemicals on violet phosphorene has been systematically studied based on density functional theory. From our results, all seven considered organic chemicals (benzoapyrene, benzene, methylbenzene, formaldehyde, m-xylene, o-xylene and p-xylene) on violet phosphorene show molecular adsorption with exothermic process. Among them, the adsorption of benzopyrene with −0.881 eV adsorption energy is most conducive for complete adsorption-desorption cycles, which is an essential feature of reversible gas sensors. Small amounts of charge transfer indicate that the adsorption mechanism is mainly van der Waals type interaction. In particular, further work function and electronic structure analysis indicates that the electrical conductivity changes significantly after benzoapyrene exposure. That makes it possible to transmit gas sensing signals using electrical strategy. We also found that violet phosphorene multilayer maintains consistent benzoapyrene adsorption performance with its monolayer, which is conducive to practical application. Our simulations could provide theoretical basis for the exploration of two-dimensional organics sensing materials.

Tri‐icosahedral Au37 cluster as a carrier/detector for anti‐cancer cisplatin drug

AbstractIn this work, DFT studies devoted to the adsorption of anti‐cancer cisplatin drug and one cationic tri‐icosahedral Au37 cluster are addressed, which are aiming to explore the application of thiolate/phosphine protected gold clusters as carriers/detectors for cisplatin molecules. The Au37 cluster is able to adsorb up to four cisplatin molecules, and the cisplatin4/Au37 complex holds a 1.71 eV adsorption energy value. Further atomic population analysis reveals that adsorbed cisplatin molecules bear major partial charges, attesting an asymmetric distribution of electrons into their bonds. Vibrational assignments of two enhanced IR and Raman signals (circa the 200‐fold boost) disclose the coupling of some normal modes of the cisplatin dimer with the Au37 cluster, making this cluster able to detect small concentrations of cisplatin molecules.

H2S adsorption and dissociation on Rh(110) surface: a first-principles study

First-principle study based on density functional theory are used to scrutinize the mechanism of H2S adsorption and dissociation over Rh(110) surface. For adsorption mechanisms, we probe the most favorite sites of H2S monomers over Rh(110) surface. It is determined that H2S vigorously adsorbed over high symmetry adsorption sites with preferred long-bridge (LB) site having adsorption energy − 1.00 eV, with no more than 0.50 eV, binding energy. Also we found that HS chemisorption is higher as compared to H2S on Rh(110) surface having − 3.76 eV adsorption energy, where atomic S and H binding at hollow and short-bridge site is more stronger. The energy barriers to split the bond of S–H in first and second H2S dehydrogenation are 0.18–0.36 and 0.30 eV. To further investigate, electronic density of state are employed to illustrate the interaction of adsorbed H2S with the surface of Rh(110), which is able to account for energy divergences of all species adsorbed on Rh(110) surface. Hence, our calculated results confirm that H2S dissociation over Rh(110) surface is exothermic as well as an easy process, however kinetically and thermodynamically the existence of atomic S avoid the breaking of H–S bond procedure.

Detection of 2,4-dinitrotoluene by graphene oxide: first principles study

The surface of graphene oxide (GO) with different oxidation level is widely used in gas sensing applications. Otherwise, detection of 2,4-dinitrotoluene (DNT) have been extensively attend as a high explosive and environmental sources by various methods. Atomic level modelling are widely employed to explain the sensing mechanism at a microscopic level. The present work is an attempt to apply density functional theory (DFT) to investigate the structural and electronic properties of GO and adsorption of oxygen atom and hydroxyl on graphene surface. The focus is on the adsorption mechanisms of DNT molecule on the GO monolayer surface to detect DNT molecule. The calculated adsorption energy of DNT molecule on the GO surface indicates physisorption mechanism with −0.7 eV adsorption energy. Moreover, basis-set superposition errors correction based on off site orbitals consideration leads to −0.4 eV adsorption energy which it is more in the physisorption regime. Consequently, the results could shed more light to design and fabrication an efficient DNT sensor based on GO layers.

The effect of solvents on formaldehyde adsorption performance on pristine and Pd doped on single-walled carbon nanotube using density functional theory

The electronic and structural properties of Pd doped single-walled carbon nanotubes show advantages as new nanocomposites that enable a wide variety of applications as nanosensors, nano storage devices, nanoplatform in biosensors. Our previous research demonstrated that Pd atom loaded onto single-walled carbon nanotubes have been shown that sensitivity of Pd/CNT toward CH2O in gas phase is twelve times opposed to intrinsic CNT. A detail and widespread study of solvent effects on adsorption of formaldehyde onto pristine single-walled carbon nanotube and Pd loaded on carbon nanotube was performed under density functional theory framework. Based on the results, carbon nanotube showed no obvious sensitivity toward formaldehyde in considered solvents including water, methanol, ethanol, acetone and carbon tetrachloride. Electronic properties of Pd/CNT after CH2O adsorption were considerably changed. Also, the most and the least adsorption energy were reported in the presence of carbon tetrachloride and methanol from O (O-Pd/CNT) and para (para-Pd/CNT) orientations with −1.174eV and −0.519eV adsorption energy respectively. NBO analyses showed in the similar transfers, there was the most strong charge transfer from formaldehyde (O orientation) to Pd/CNT in carbon tetrachloride solution through lone pair of O atom toward lone pair* of Pd site with second-order perturbation energy (E(2)) equal 113.345kJ/mol. These results are representative of strong chemisorption between CH2O and Pd/CNT in the presence of carbon tetrachloride. Quantum theory of atom in molecule (QTAIM) calculations indicate that the most accumulated electron charge density was between Pd-O in the O-Pd/CNT in carbon tetrachloride organic solution.

Simple benzene derivatives adsorption on defective single-walled carbon nanotubes: a first-principles van der Waals density functional study

We have investigated the interaction between open-ended zig-zag single-walled carbon nanotube (SWCNT) and a few benzene derivatives using the first-principles van der Waals density functional (vdW-DF) method, involving full geometry optimization. Such sp (2)-like materials are typically investigated using conventional DFT methods, which significantly underestimate non-local dispersion forces (vdW interactions), therefore affecting interactions between respected molecules. Here, we considered the vdW forces for the interacting molecules that originate from the interacting π electrons of the two systems. The -0.54 eV adsorption energy reveals that the interaction of benzene with the side wall of the SWCNT is typical of the strong physisorption and comparable with the experimental value for benzene adsorption onto the graphene sheet. It was found that aromatics are physisorbed on the sidewall of perfect SWCNTs, as well as at the edge site of the defective nanotube. Analysis of the electronic structures shows that no orbital hybridization between aromatics and nanotubes occurs in the adsorption process. The results are relevant in order to identify the potential applications of noncovalent functionalized systems.

Effect of Surface Deposited Pt on the Photoactivity of TiO2

The roles of deposited Pt clusters and adsorbed O2 in the photoactivity of anatase TiO2 (101) surfaces have been studied using density functional theory. O2 only adsorbs to TiO2 surfaces when excess negative charge is available to form O–Ti bonds, which can be provided by a photoexcited electron or subsurface oxygen vacancy, in which cases the adsorption energies are −0.94 and −2.52 eV, respectively. When O2 adsorbs near a subsurface defect, it scavenges extra electron density and creates a hole that can annihilate excited electrons. In aqueous solutions, O2 interactions with the TiO2 surface are rare because water preferentially adsorbs at the surface. Pt clusters on TiO2 significantly enhance O2 adsorption providing many adsorption sites with adsorption energies up to −1.69 eV, stronger than the −0.52 eV adsorption energy of H2O on the Pt cluster. Consequently, Pt increases the rate of electron scavenging by O2 relative to that of undoped TiO2 leading to enhanced photocatalytic performance. Pt states co...

Two bonding configurations for individually adsorbedC60molecules on Au(111)

Two distinct bonding configurations have been identified for individually adsorbed ${\text{C}}_{60}$ molecules on the elbow site of Au(111) using scanning tunneling microscopy: a strong bonding configuration where the molecule sits in a single-atomic-layer-deep pit and a weak bonding configuration where the molecule sits directly above the dislocation of the elbow site. Density-functional theory calculations show that the most stable strong bonding configuration involves the molecule sitting inside a seven-atom pit with 2.56 eV adsorption energy.

Density functional study of the adsorption of aspirin on the hydroxylated (0 0 1) [formula omitted]-quartz surface

In this study the adsorption geometry of aspirin molecule on a hydroxylated (0 0 1) α -quartz surface has been investigated using DFT calculations. The optimized adsorption geometry indicates that both, adsorbed molecule and substrate are strongly deformed. Strong hydrogen bonding between aspirin and surface hydroxyls, leads to the breaking of the original hydroxyl–hydroxyl hydrogen bonds (Hydrogenbridges) on the surface. In this case new hydrogen bonds on the hydroxylated (0 0 1) α -quartz surface appear which significantly differ from those at the clean surface. The 1.11 eV adsorption energy reveals that the interaction of aspirin with α -quartz is an exothermic chemical interaction.

Gas Phase Formation of Dense Alkanethiol Layers on GaAs(110)

We present a study of the growth and thermal stability of hexanethiol (C6) films on GaAs(110) by direct recoil spectroscopy with time-of-flight analysis. We compare our results with the better known case of C6 adsorption on Au(111). In contrast to the two-step adsorption kinetics observed for Au surfaces after lengthy exposures, data for C6 adsorption on the GaAs(110) surface are consistent with the formation of a single dense phase of C6 molecules at lower exposures. On the contrary, in solution preparation, dense phases can only be obtained on GaAs for long alkanethiols and after lengthy immersions. The C6 layer has a first desorption peak at 325 K, where partial desorption of the alkanethiol molecules takes place. Fits to the desorption curves result in a 1 eV adsorption energy, in agreement with a chemisorption process. Increasing the temperature to 500 K results in the S-C bond scission with only S remaining on the GaAs(110) surface. The possibility of forming dense, short-alkanethiol layers on semiconductor surfaces from the vapor phase could have a strong impact for a wide range of self-assembled monolayer applications, with only minimal care not to surpass room temperature once the layer has been formed in order to avoid molecular desorption.

DFT investigation of HfCl4 decomposition on hydroxylated SiO2: first stage of HfO2 atomic layer deposition

Density functional theory is used to address the initial stage of HfO2 growth on hydroxylated SiO2 as a part of atomic layer deposition process of HfO2 on Si(100). We perform a constrained minimization procedure to investigate the reaction pathway of the HfCl4 molecular precursor decomposition on ultra-thin SiO2. This is done through the static excitation of one single normal vibrational mode of the precursor molecule. We find a chemisorbed state with an associated 0.48 eV adsorption energy. Starting from this minimum, and using the above pathway, an activation barrier of 0.88 eV is determined to arrive at a complex intermediate. Then the reaction end product is determined giving rise to a HCl adsorbed molecule on the surface.