Defect engineering for high-selection-performance of NO reduction to NH3 over CeO2 (111) surface: A DFT study

A two-dimensional covalent organic framework with single-atom manganese for electrochemical NO reduction: a computational study

Covalent organic frameworks (COFs) exhibit great potential for electrocatalysis. Here, using DFT calculations and constant-potential modelling, we report the feasibility of a series of COFs toward NO reduction via regulating their central metal atoms and linking ligands. A COF with single-atom Mn is identified to possess superior activity while maintaining high NH3 selectivity.

Utility of structural engineering on the monitoring of acrolein by aluminum nitride nano tube

CONTEXT

The study delves into the adsorption process of acrolein (AC) onto both an untainted and a titanium-doped aluminum nitride nanotube (AlNNT) using computations based on density functional theory. As AC approaches the pure AlNNT, it exhibits a calculated adsorption energy (Ead) of -5.3 kcal/mol, underscoring the feeble nature of the adsorption. Furthermore, there has been very little change to the AlNNT's natural electrical characteristics. On the contrary, the introduction of titanium (Ti) enhances the performance of AlNNT, rendering it more susceptible and reactive to AC signals. Analyzing the conventional Gibbs free energy of formation computationally, we ascertain that replacing a nitrogen (N) atom with a titanium (Ti) atom within the aluminum nitride nanotube (AlNNT) structure presents a more advantageous prospect. Notably, there is a substantial alteration in the energy of adsorption (Ead) for AC as a Ti atom is incorporated onto the AlNNT surface, resulting in a shift from -5.3 to -24.6 kcal/mol.

METHODS

Energy calculations and geometric optimizations were conducted utilizing the dispersion-augmented B3LYP method, known as B3LYP-D. In this approach, Grimme's dispersion term, referred to as the "D" term, was employed to account for dispersion forces. The basis set adopted was 6-31 +  + G** (d), and all computational procedures were executed using the GAMESS software program. Following the incorporation of titanium (Ti), this adjustment leads to a substantial enhancement in sensing capability, reaching a value of 93.7. This indicates an improved electrical conductivity of the aluminum nitride nanotube (AlNNT). Remarkably, the Ti-doped AlNNT demonstrates the ability to detect AC distinctly, even in the presence of HCN, formaldehyde, ethanol, toluene, and acetone. The swift recovery process becomes evident as AC desorbs from the surface of Ti-doped AlNNT, with a calculated recovery time of 14.0 s.

The β-PdBi2 monolayer for efficient electrocatalytic NO reduction to NH3: a computational study

β-PdBi2 was proposed as a novel NORR catalyst for NH3 synthesis with high efficiency and high selectivity, and its catalytic activity can be enhanced by a tensile strain.

Nitrogen Reduction Reaction Catalyzed by Diatomic Metals Supported by N-Doped Graphite

In this article, for the transition metal-nitrogen ligand Mn-M@N6-C (M = Ag, Bi, Cd, Co, Cr, Cu, Fe, Hf, Ir, Mo, Nb, Ni, Os, Pd, Pt, Re, Rh, Ru, Sc, Ta, Tc, V, Y, Zn, Zr, Ti, W), by comparing the amount of change in the length of the N-N triple-bond, and calculating the adsorption energy of N2 and the change of charge around N2, it is shown that the activation effect of Sc, Ti, Y, Nb-Mn@N6-C on the single-atomic layer of graphite substrate is relatively good. The calculation of structural stability shows that the Mn-M@N6-C (M = Sc, Ti, Y) load is relatively stable when it is on the single-atomic layer of the graphite substrate. Through calculations, a series of data such as the adsorption free energy and reaction path are obtained, and the final results show that the preferred reaction mechanism of NRR is the alternating path on Mn-Ti@N6-C, and the reaction limit potential is only 0.16 eV, Mn-Ti@N6-C and has good NRR activity. In addition, the vertical path on Mn-Y@N6-C has a reaction limit potential of 0.39 eV. Mn-Y@N6-C also has good NRR catalyzing activity.

Efficient electrocatalytic reduction of NO to ammonia on BC3 nanosheets

Searching for an economical and highly efficient electrocatalytic reduction catalyst for ammonia synthesis under controllable conditions is a very attractive and challenging subject in chemistry. In this study, we systematically studied the electrocatalytic performance of BC₃ nanosheets as potential NO reduction reaction (NORR) electrocatalysts using density functional theory (DFT) calculations. It was found that BC₃ two-dimensional (2D) materials exhibit excellent catalytic activity with a very low limiting potential of -0.29/-0.11 V along three reaction paths. The total reaction is NO (g)+5H⁺+5e^-→NH₃(g)+ H₂O. The density of states of adsorbed NO, NH_3, and the corresponding crystal orbital hamiltonian population (COHP) analysis revealed the mechanism of NO being activated and the reasons for NH₃ adsorption/desorption on the surface of BC₃. The reaction path, limiting potential, and Gibbs free energy calculations of BC₃ catalyzed NO to ammonia synthesis revealed that for path 1, the potential-determining step is *NO+H⁺+e^-→*NOH, and for path 2/3 the potential-determining step is *NO+(H⁺+e^-)→*HNO. Calculation of the thermodynamic energy barriers for NO dissociation at the BC₃ surface and NO hydrogenation reveals that NO is more likely to be hydrogenated rather than dissociated. The influences of the proton-electron hydrogenation site on the process of ammonia synthesis in the key reduction step were analyzed by Bader charge analysis and charge density, it is pointed out that the electronic structure and affects the reaction process can be controlled by hydrogenation at different sites of intermediates. These results pave the way for using nitrogen oxides not just nitrogen as raw materials for ammonia synthesis with 2D materials.

Adsorption Characteristics of Gas Molecules Adsorbed on Graphene Doped with Mn: A First Principle Study

Herein, the adsorption characteristics of graphene substrates modified through a combined single manganese atom with a vacancy or four nitrogen to CH₂O, H₂S and HCN, are thoroughly investigated via the density functional theory (DFT) method. The adsorption structural, electronic structures, magnetic properties and adsorption energies of the adsorption system have been completely analyzed. It is found that the adsorption activity of a single vacancy graphene-embedded Mn atom (MnSV-GN) is the largest in the three graphene supports. The adsorption energies have a good correlation with the integrated projected crystal overlap Hamilton population (-IpCOHP) and Fermi softness. The rising height of the Mn atom and Fermi softness could well describe the adsorption activity of the Mn-modified graphene catalyst. Moreover, the projected crystal overlap Hamilton population (-pCOHP) curves were studied and they can be used as the descriptors of the magnetic field. These results can provide guidance for the development and design of graphene-based single-atom catalysts, especially for the support effect.

Sensing of Acetaminophen Drug Using Zn-Doped Boron Nitride Nanocones: a DFT Inspection

During environmental testing, scientists face the problem of developing and designing a new type of sensor electrode with distinguished stability, high activity, and cost-effectiveness to detect acetaminophen (ACE). Density functional theory (DFT) calculations were used to investigate the interaction and electrical response of Zn-doped and pristine boron nitride nanocones (BNNCs) with and to ACE with the disclination angle of 240°. The adsorption energy for ACE in the Zn-doped was - 56.94 kJ.mol^-1. This value for BNNCs was approximately - 26.11 kJ.mol^-1. Furthermore, after the adsorption of ACE, the value of band gap (E_g) for Zn-doped BNNCs decreased significantly (from 4.01 to 3.10 eV), thereby increasing the electrical conductivity. However, E_g value of the pristine BNNCs decreased marginally after the adsorption of ACE. Compared with the pristine BNNCs, the Zn-doped BNNCs could be considered promising materials for the detection of ACE and could be employed in electronic sensors. In the Zn-doped BNNCs, the molecular and electrostatic interactions and the creation of Zn-O bond played key roles in the adsorption of ACE. The Zn-doped BNNCs had other merits such as slight recovery time which was approximately 7.09 ms for the desorption of ACE at ambient temperature.

Boosting electrochemical nitrite-ammonia conversion properties by a Cu foam@Cu2O catalyst

Electrocatalytic reduction of nitrite (NO₂^-) to ammonia (NH₃) can simultaneously achieve wastewater treatment and ammonia production, but it needs efficient catalysts. Herein, Cu₂O particles self-supported on Cu foam with enriched oxygen vacancies are developed to enable selective NO₂^- reduction to NH₃, exhibiting a maximum NH₃ yield rate of 7510.73 μg h^-1 cm^-2 and high faradaic efficiency of 94.21% at -0.6 V in 0.1 M PBS containing 0.1 M NaNO₂. Density functional theory calculations reveal the vital role of oxygen vacancies during the nitrite reduction process, as well as the reaction mechanisms and the potential limiting step involved. This work provides a new avenue to the rational design of Cu-based catalysts for NH₃ electrosynthesis.

B-Doped 2D-InSe as a bifunctional catalyst for CO2/CH4 separation under the regulation of an external electric field

The separation of CO₂ or CH₄ from a CO₂/CH₄ mixture has drawn great attention in relation to solving air pollution and energy shortage issues. However, research into using bifunctional catalysts to separate CO₂ and CH₄ under different conditions is absent. We have herein designed a novel B-doped two-dimensional InSe (B@2DInSe) catalyst, which can chemically adsorb CO₂ with covalent bonds. B@2DInSe can separate CO₂ and CH₄ in different electric fields, which originates from different regulation mechanisms by an electric field (EF) on the electric properties. The hybridization states between CO₂ and B@2DInSe near the Fermi level have experienced gradual localization and eventually merged into a single narrow peak under an increased EF. As the EF further increased, the merged peak shifted towards higher energy states around the Fermi level. In contrast, the EF mainly alters the degree of hybridization between CH₄ and B@2DInSe at states far below the Fermi level, which is different from the CO₂ situation. These characteristics can also lead to perfect linear relationships between the adsorption energies of CO₂/CH₄ and the electric field, which may be beneficial for the prediction of the required EF without large volumes of calculations. Our results have not only provided novel clues for catalyst design, but they have also provided deep understanding into the mechanisms of bifunctional catalysts.