111,889 research outputs found
Gallium Nitride-based Materials as Promising Catalysts for CO2 Reduction: A DFT Study on the Effect of CO2 Coverage and the Incorporation of Mg Doping or Substitutional In
No full textCatalytic CO2 conversion to fuels and chemicals is important for mitigating the climate change and reducing the dependence on fossil resources. In order to achieve this goal on a large industrial level, effective catalysts need to be developed. Among them, gallium nitride (GaN) and related Mg-doped and In-alloyed systems have been proven as efficient materials for the reduction of highly stable CO2 molecules. This work presents a density functional theory (DFT) investigation, performing periodic boundary condition (PBC) calculations which allow to employ a more extended surface for a detailed analysis of the CO2 coverage, and the effect of Mg doping and In alloying on the CO2 adsorption and its conversion to CO. The results show the great potential of GaN(100) surfaces to simultaneously bind and strongly activate multiple CO2 molecules, which is a crucial aspect for an efficient CO2 conversion process. Moreover, the presence of Mg-dopant on the top layer is found to be more beneficial for the CO2 adsorption and activation with respect to both the pristine and In-alloyed system, and this effect is further improved by the inclusion of a second impurity on the top layer. In line with the previous experimental findings, these calculations support the potential of pristine GaN(100) to catalyze the CO2-to-CO reduction. The results presented here offer crucial information for the development of more efficient and selective catalysts for the CO2 reduction
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Density Functional Theory Study and Photocatalytic Activity of ZnO/N-Doped TiO2Heterojunctions
No full textThe beneficial effects on ZnO and TiO2photocatalytic activity resulting from a suitable combination of doping and heterojunctions were proposed and investigated by a synergistic experimental and theoretical study. In detail, the ZnO/N-doped TiO2heterojunction was synthesized and tested in the photocatalytic degradation of atrazine under UV and visible light. Wide-angle X-ray diffraction (WAXD) analysis reveals the presence of both ZnO and TiO2crystalline phases in the heterojunction. UV-vis DRS analysis shows that the simultaneous presence of ZnO and N-doped TiO2in the heterojunction results in a slight increase in the band gap value in the UV region, while the shoulder in the visible region typically of bare N-doped TiO2is preserved. On the basis of these experimental observations, density functional theory (DFT) calculations were carried out to model both the N-doped TiO2structure and to rationalize the experimental decrease in the band gap energy. The DFT modeling of band alignment of the ZnO/N-doped TiO2heterojunction allowed us to define the "minimal band gap" (MBG), corresponding to the interface gap, which resulted in smaller band gap energy than the two separate semiconductor band gaps. Furthermore, the DFT modeling of the electronic structure of N-doped TiO2predicted the existence of additional energy levels between the TiO2valence and conduction bands, which allowed us to justify the activity of the heterojunction under visible light irradiation. Photocatalytic tests showed that the ZnO/N-doped TiO2heterojunction performance was better than that of both N-doped TiO2and ZnO alone, allowing us to achieve almost complete atrazine degradation under UV light irradiation, whereas 24% of atrazine degradation was achieved after 180 min of visible light irradiation. Finally, the photocatalytic results achieved by using scavenger molecules for reactive oxygen species showed that ·OH and ·O2-are both reactive species in atrazine photocatalytic degradation under UV irradiation, while ·OH is responsible for the photocatalytic processes under visible irradiation. DFT modeling, validated by these results, finally allowed us to define a model of the band alignment and photogenerated charge-transfer mechanism for the ZnO/N-doped TiO2heterojunction
Telephone counseling for sexual problems: 2007-2013 activity of the Institute of Clinical Sexology of Rome.
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Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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