Generally, in terms of electrocatalytic CO2 reduction, single‐atom catalysts show high selectivities yet low current densities whereas conventional nanoparticle catalysts exhibit relatively high current densities but low selectivities. This work combines the advantages of the two classes of catalysts by constructing a Ni‐Gd‐N‐doped carbon black electrocatalyst within which NiI active sites are exposed outside the carbon layers and Ni nanoparticles are encapsulated inside the carbon layers. The Gd atoms can not only influence the local electron densities of Ni 3d orbitals, thus strengthening the electronic activity, but also tailor the sizes of the Ni nanoparticles, thereby minimizing the activity toward hydrogen evolution. Accordingly, this electrocatalyst yields both a high CO faradaic efficiency (97 %) and a large current density (308 mA cm−2), alongside an outstanding stability (100 h).
Based on density functional theory(DFT), using virtual crystal approximation and generalized gradient approximation(GGA)with pseudopotential method, the lattices and energies for five crystallines of vanadium hydrides are optimized and calculated. The phonon densities of states are calculated based on density functional perturbation theory(DFPT). The standard Heat capacities, Entropies, Helmholtz free energies and Gibbs functions of vanadium and its hydride are deduced at 298.15K. The calculated results are discussed and compared with experimental data.
In this paper, the electronic structure and photoelectric properties of P and Cu doped ZnO systems have been studied by Density functional theory method. The results show that the formation energies of ZnO-P-Cu, ZnO-P-2Cu, ZnO-P and ZnO-Cu systems decrease in turn Compared with the intrinsic ZnO system, the ZnO-P, ZnO-P-Cu, ZnO-P-2Cu and ZnO-Cu systems have higher activity, the band gap of ZnO-P and ZnO-P-2Cu systems is reduced, and the electron transition is easier. In the doped system, the peak of the dielectric function shifts to the left and increases, the absorption of the electron to the photon increases obviously, and the absorption spectrum appears red shift, from the calculated results, it can be concluded that P and Cu single-doped and co-doped ZnO have great influence on the electronic structure and optical properties of ZnO system, which provides a theoretical basis for further study of the influence of doping on the properties of ZnO.
In this paper, the electronic structure and photo-electric properties of N and Fe co-doped ZnO systems have been studied by using Density functional theory method. The results show that the formation energy of ZnO-N, ZnO-Fe, ZnO-N-Fe and ZnO-N-2Fe systems decreases in turn, the doping is easier to realize. Compared with the ZnO system, the activity of ZnO-Fe, ZnO-N-Fe and ZnO-N-2Fe systems increases in turn, the band gap of ZnO-N and ZnO-N-2Fe systems decreases, and the electron transition is easier in the doped system. The peak of the dielectric function shifts to the left, the absorption of the electron to the photon increases obviously, and the absorption spectrum appears red shift. It can be concluded that the electronic structure and optical properties of ZnO are greatly affected by the single and co-doping of N and Fe, which provides a theoretical basis for the further study.
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