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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.

Based on the first principles of density functional theory, the adsorption behavior of H2CO on original monolayer MoS2 and Zn doped monolayer MoS2 was studied. The results show that the adsorption of H2CO on the original monolayer MoS2 is very weak, and the electronic structure of the substrate changes little after adsorption. A new kind of surface single cluster catalyst was formed after Zn doped monolayer MoS2, where the ZnMo3 small clusters made the surface have high selectivity. The adsorption behavior of H2CO on Zn doped monolayer MoS2 can be divided into two situations. When the H-end of H2CO molecule in the adsorption structure is downward, the adsorption energy is only 0.11 and 0.15 eV and the electronic structure of adsorbed substrate changes smaller. When the O-end of H2CO molecule is downward, the interaction between H2CO and the doped MoS2 is strong leading to the chemical adsorption with the adsorption energy of 0.80 and 0.98 eV. For the O-end-down structure, the adsorption obviously introduces new impurity states into the band gap or results in the redistribution of the original impurity states. All of these may lead to the change of the chemical properties of the doped MoS2 monolayer, which can be used to detect the adsorbed H2CO molecules. The results show that the introduction of appropriate dopant may be a feasible method to improve the performance of MoS2 gas sensor.

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.

A Bayesian optimisation algorithm for deep learning crystal structure prediction software (CBD-GM) is used to predict the structures of Cu(I) and Cu(II) oxides of 2D and 3D materials. Two known 2D structures and two known 3D structures were anticipated, in addition to the prediction of 5 novel structures. All nine structures were optimised and analysed using density-functional theory (DFT). Firstly, DFT calculations using the PBE functional indicate that the structures should be thermodynamically and dynamically stable. Secondly, we calculated the elastic constants using the ‘‘stress–strain’’ method, and the predicted Young’s modulus and Poisson’s ratios of the materials suggest that they all should have excellent ductile mechanical properties. Calculations of the band structure of the materials performed using the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional indicate that some of the materials should be semiconductors with useful bandgaps. The results therefore provide inspiration for the synthesis of new copper oxides for industrial applications. [ABSTRACT FROM AUTHOR]

The elastic and thermoelectric properties of Ca5Al2Sb6 under pressure are studied using ab initio calculation and semiclassical Boltzmann theory. The calculated elastic constants and minimum thermal conductivity indicate that Ca5Al2Sb6 exhibits an anisotropic structure and high thermoelectric performance. The size of the band gap shows a nonlinear change with increasing pressure. Based on the electronic structure, the calculated thermoelectric parameters show that the Seebeck coefficient has no obvious change under pressure, whereas the electrical conductivity improves with increasing pressure. Therefore, the power factor increases at an appropriate pressure of P=2.6 GPa. P-type doping of Ca5Al2Sb6 may achieve better thermoelectric performance than n-type doping, in agreement with experiment. The anisotropic thermoelectric properties of Ca5Al2Sb6 indicate that the thermoelectric performance along the z-direction is superior to other directions. This is attributed to the combination of the large dispersion and high band degeneracy along the Γ-Z direction in the band structure. [ABSTRACT FROM AUTHOR]

The electrocatalytic nitrogen reduction reaction (NRR) performed under ambient conditions has provided alternative routes to realize green NH3 synthesis. Herein, the process of NRR has been investigated on transition metal (TM = Fe, Co, and Ni) single atoms supported by Bn-doped (n = 1-3) graphyne (GY) using density functional theory (DFT) calculations. We successfully identified FeB@GY as an ideal electrocatalyst via the distal pathway with a minimum limiting potential of -0.53 V. Additionally, the FeB@GY surface can efficiently promote electron transfer efficiency and significantly improve the stability of intermediate adsorption during the NRR. [ABSTRACT FROM AUTHOR]