Modulating electron density of vacancy site by single Au atom for effective CO2 photoreduction

The surface electron density significantly affects the photocatalytic efficiency, especially the photocatalytic CO2 reduction reaction, which involves multi-electron participation in the conversion process. Herein, we propose a conceptually different mechanism for surface electron density modulation based on the model of Au anchored CdS. We firstly manipulate the direction of electron transfer by regulating the vacancy types of CdS. When electrons accumulate on vacancies instead of single Au atoms, the adsorption types of CO2 change from physical adsorption to chemical adsorption. More importantly, the surface electron density is manipulated by controlling the size of Au nanostructures. When Au nanoclusters downsize to single Au atoms, the strong hybridization of Au 5d and S 2p orbits accelerates the photo-electrons transfer onto the surface, resulting in more electrons available for CO2 reduction. As a result, the product generation rate of AuSA/Cd1−xS manifests a remarkable at least 113-fold enhancement compared with pristine Cd1−xS.

Mechanism of oxygen vacancy assisted water-splitting of LaMnO3: inorganic perovskite prediction for fast solar thermochemical H2 production

The mechanism of water-splitting and H2 production around the oxygen vacancy site of the LaMnO3 defective surface is explored for the purpose of quick identification of kinetically favorable dopants such as Mo.

A Density Functional Theory Study on the Diffusion of Fission Gas Atoms in Uranium Dioxide

Uranium dioxide (UO2) is the typical fuel that is used in the current nuclear power plant; fission gas atoms are produced during and after the nuclear reactor operation; the fission gas atoms have a significant effect on the performance of UO2 fuel in the nuclear reactor. In this paper, we investigated the diffusion of the fission gas atoms in the UO2 fuel by using the first-principles calculation method based on the density functional theory (DFT). The results indicate that the volume of the UO2 cell increased when there is a fission gas atom enters in the UO2 supercell; the elastic properties of UO2 are in good agreement with other simulation results and experimental data and the fission gas atoms make the ductility of UO2 decreased; the fission gas atoms prefer to occupy the octahedral interstitial site (OIS) over the uranium vacancy site and the oxygen vacancy site, and the oxygen vacancy site is the most difficult occupied site due to the formation of an oxygen vacancy is more difficult than that of the uranium vacancy; the diffusion barrier of a He atom in the UO2 supercell is higher than that of an oxygen atom, that means that the diffusion of the He atom in UO2 fuel is weaker than that of the oxygen atom. Our works may shed some light on the formation mechanism of the bubbles caused by the fission gas atoms in the UO2 fuel.

Precise mono-Cu+ ion doping enhanced electrogenerated chemiluminescence from Cd–In–S supertetrahedral chalcogenide nanoclusters for dopamine detection

Atomically precise Cu+ doping into the vacancy site of supertetrahedral chalcogenide nanoclusters can significantly enhance their electrogenerated chemiluminescence efficiency, and can be used for dopamine detection.

Diffusion of Fission Gas in Uranium Dioxide: A First-Principles Study

Uranium dioxide (UO2) is the typical fuel that is used in nuclear fission reactor, fission gas are produced during and after the reactor operation, and the fission gas have a significant impact on the performance of UO2 in reactor. In this paper, we investigated the effects of the fission gas on the performance of UO2 by using the first-principles calculation method based on the density functional theory. The results are that, the volume of UO2 increased when there is a fission gas atom enter in UO2 supercell; fission gas prefer to occupy the octahedral interstitial site over the uranium vacancy site and the oxygen vacancy site, and the oxygen vacancy site is the most difficult occupied site due to the formation of an oxygen vacancy is more difficult than that of the uranium vacancy; our results of the UO2 elastic constants are in good agreement with other simulation results and experimental data, and the fission gas atoms make the ductility of UO2 decreased. Our works may shed some light on the development of the UO2 fuel and the spent fuel reprocessing.

Surface Fe vacancy defects on haematite and their role in light-induced water splitting in artificial photosynthesis

A pathway for water dissociation near a surface Fe vacancy site on a hematite surface with photogenerated holes.