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Successful catalytic conversion of carbon dioxide into high-value chemicals, as a means of abating global CO2 emissions is a pressing challenge. Herein, we report on an ambient pressure x-ray photoelectron spectroscopy study of CO2 hydrogenation reaction using a mixed gas of CO2 and H2 at a pressure up to 0.1 mbar on polycrystalline nickel-gallium thin films prepared by vacuum co-deposition that are compositionally equivalent to Ni, Ni3Ga, Ni5Ga3 and NiGa2, which are some noted low pressure methanol synthesis catalysts. Ni film is very reactive at 300 K, with the reaction sequence initiated by facile CO2 dissociation, yielding C2O4−2, CO3−2, CO2− and CO, but little HCOO− and HCO3−. The product species observed on NiGa alloy films are not generally different from those observed from using Ni film but are now of different proportions. The NiGa2 film, with the highest Ga content, is the least reactive, as judged by a dominant molecular adsorption feature of CO2. Interestingly, the NiGa alloys are found to undergo composition change and surface restructuring induced by the reactant gas and heating during the reaction. A surface depletion of Ni and a surface enrichment of oxidic Ga are found to occur and continue unabated toward high temperature. For example, for the alloy film with a composition similar to that of Ni5Ga3 when exposed to the mixed gas at 500 K for the duration of measurements (a few h), the near surface region delimited by an XPS probing depth (3λ) of 36 Ĺ is composed of 29% Ni, 24% Ga, and 47% oxidic Ga vs. 62% Ni, 34% Ga, and 4% oxidic Ga for the freshly prepared film at 300 K. Our study demonstrates that a complex interplay exists between the surface reactivity and the evolving chemical makeup as the alloy films are exposed to the reactive gas at elevated pressure and temperature. [ABSTRACT FROM AUTHOR]

Bimetallic nanostructured core-shell structures are commonly used as catalysts in a wide variety of reactions. We surmised that the addition of an additional metal would potentially allow catalytic tailoring with the possibility of an increase in activity. Here a tri-metallic catalytic structure, consisting of clustered catalytic Pt on the surface of a Pd shell supported on a rod shaped Au core was fabricated. The significance of the additional metallic component is shown by comparative electrochemically active surface area (ECSA) analysis results for the trimetallic Aurod-Pdshell-Ptcluster, bimetallic Aurod-Ptcluster and monometallic JM-Pt (used as a reference), which have respective ECSA values (cm2/mgPt) of 1883.0, 1371.7 and 879. The potential utility of the trimetallic catalysts was shown in a hydrogen peroxide sensing protocol, which showed the catalyst to have a sensitivity of 604 ìA/mMcm2 within a linear range of 0.0013-6.191 mM. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated the dependence of crystallographic characteristics and electronic structures on indium amounts in the indium-zinc-selenium alloy fabricated by vapour-phase deposition. By taking advantage of molecular beam epitaxy and a synchrotron radiation apparatus, it is shown for the first time that the significant difference in vapour pressure between zinc and indium induced zinc deficiency in the solid state and resulted in a transition of five distinct phases in the whole range of the alloy from zinc selenide to indium selenide. The binary ZnSe with indium dopants, the ZnSe-rich alloy with a minority of ZnIn2Se4, the disordered structure owing to the comparable mixture of ZnSe and ZnIn2Se4, the ZnIn2Se4-rich alloy with a minority of ZnSe, and the binary In2Se3 phase are separated by indium incorporation ratios of 0.01, 0.02, 0.18, and 0.69, respectively. Moreover, a pronounced carrier localisation effect was observed in the ZnSe-rich and the disordered mixture. The widely distributed mid-gap states were attributed to a high density of zinc vacancies in the ZnSe-based lattice. In brief, these fundamental properties show the feasibility of Se-based II-III2-VI4 alloys for optoelectronics. [ABSTRACT FROM AUTHOR]

This study examined the reasons players help others in the virtual space of online games. Results of an online empirical survey indicated that both altruism and reciprocity influence prosocial behavior simultaneously. Additionally, the study found that male players are more likely than female players to seek friendship of opposite sex. [ABSTRACT FROM AUTHOR]

A proper design of the injection barrier between a source electrode and an active layer is essential to achieve high-performance vertical organic field-effect transistors (VOFETs). Here, we show that a modification of metallic source electrodes with thiol-based self-assembled monolayers (SAMs) is effective in controlling the electrode work function and injection barrier into the active layer, leading to a significantly reduced off-current and undegraded on-current in an optimized VOFET. For the studied C60 VOFETs with Ag electrodes, the on/off ratio improves from <10 to 103–104 when the injection barrier is varied from 0.02 to 0.33 eV by SAM modification. [ABSTRACT FROM AUTHOR]