Electronic and electrocatalytic properties of PbTiO3: unveiling the effect of strain and oxygen vacancy

First-principles calculations based on density-functional theory have been used to investigate the effect of biaxial strain and oxygen vacancy on the electronic, photocatalytic, and electrocatalytic properties of PbTiO3 oxide. Our results show that PbTiO3 has a high exciton binding energy and a band gap that can be easily moderated with different strain regimes. From a reactivity viewpoint, the highly exothermic adsorption of hydrogen atoms in both pristine and strained PbTiO3 structures does not make it a potential electrocatalyst for the hydrogen evolution reaction. Fortunately, the presence of oxygen vacancies on the PbTiO3 surface induces moderate adsorption energies, making the reduced PbTiO3 suitable for hydrogen evolution reaction processes

Multiple job-holding among male workers in Greece

This paper studies the incidence of multiple job-holding in Greece and contributes to the literature by examining its determinants, its variance across different regions and the effect of the business cycle on its occurrence. The empirical analysis highlights the importance of both pecuniary and non-pecuniary motives behind multiple job-holding, and reveals significant variations in its incidence across regions, with areas that have a large primary sector having higher multiple job-holding rates. Finally, multiple job-holding is found to be pro-cyclical, with the probability of holding a second job estimated to increase during economic expansions

Impact of Sn doping on the hydrogen detection characteristics of ZnO thin films: Insights from experimental and DFT combination

The development of efficient chemical sensors based on semiconductor oxides is a major challenge. Low-cost equipment fabrication with a high sensor response towards H2 was the aim of our work. Chemical sensors were elaborated using zinc oxide, aluminum- and tin-doped zinc oxide. The samples were synthesized with a cost-effective chemical spray pyrolysis technique. Sn-doped ZnO response to hydrogen gas is the highest followed by ZnO and Al-doped ZnO, with a high sensitivity reaching 200 at 500 ppm, for 400 °C. DFT calculations revealed that O2 is strongly adsorbed on the ZnO-Al surface, resulting in the cancellation of the electrical conductance. Consequently, the approaching H2 gas will not possess sufficient energy to extract the strongly adsorbed oxygen from the surface, and no trapped electrons can be released back to the surface. In contrast, DFT calculations highlighted the potential of ZnO and Sn-doped ZnO to be used as hydrogen gas sensors. Charge transfer analysis revealed that only a small release of the trapped electrons occurs on the pure ZnO surface (0.14|e|), compared to Sn doped ZnO, in which a full release of free electrons was observed, resulting in a more favorable response to H2 and confirming the experimental results

The Relationship Between Macroeconomic Variables and Relative Price Variability in Greek Agriculture

The purpose of this paper is to present a measure of relative price variability (RPV) among 53 agricultural products and to explore the relationships between RPV, aggregate inflation rate, and changes in economic activity for the period 1962–1997. We also estimate the effects of expected and unexpected components of inflation on price variability. The results show that changes in inflation rate and economic activity have a strong positive effect on RPV, in addition, expected inflation is found to be an important determinant for explaining price variability. Copyright International Atlantic Economic Society 2005E31, Q11,