The active chemical state of zinc (Zn) in a zinc-copper (Zn-Cu) catalyst during carbon dioxide/carbon monoxide (CO ₂ /CO) hydrogenation has been debated to be Zn oxide (ZnO) nanoparticles, metallic Zn, or a Zn-Cu surface alloy. We used x-ray photoelectron spectroscopy at 180 to 500 millibar to probe the nature of Zn and reaction intermediates during CO ₂ /CO hydrogenation over Zn/ZnO/Cu(211), where the temperature is sufficiently high for the reaction to rapidly turn over, thus creating an almost adsorbate-free surface. Tuning of the grazing incidence angle makes it possible to achieve either surface or bulk sensitivity. Hydrogenation of CO ₂ gives preference to ZnO in the form of clusters or nanoparticles, whereas in pure CO a surface Zn-Cu alloy becomes more prominent. The results reveal a specific role of CO in the formation of the Zn-Cu surface alloy as an active phase that facilitates efficient CO ₂ methanol synthesis.

Efficient oxygen evolution reaction (OER) electrocatalysts are pivotal for sustainable fuel production, where the Ni-Fe oxyhydroxide (OOH) is among the most active catalysts for alkaline OER. Electrolyte alkali metal cations have been shown to modify the activity and reaction intermediates, however, the exact mechanism is at question due to unexplained deviations from the cation size trend. Our X-ray absorption spectroelectrochemical results show that bigger cations shift the Ni^2+/(3+δ)+ redox peak and OER activity to lower potentials (however, with typical discrepancies), following the order CsOH > NaOH ≈ KOH > RbOH > LiOH. Here, we find that the OER activity follows the variations in electrolyte pH rather than a specific cation, which accounts for differences both in basicity of the alkali hydroxides and other contributing anomalies. Our density functional theory-derived reactivity descriptors confirm that cations impose negligible effect on the Lewis acidity of Ni, Fe, and O lattice sites, thus strengthening the conclusions of an indirect pH effect.

Background: There has been a surge in interest in examining internet gaming disorder (IGD) and its associations with gaming motivation. Three broad components of gaming motivation have been proposed: achievement, immersion, and social. Achievement-oriented players are motivated by gaining in-game rewards, immersion-oriented players are motivated by the experience of immersion in the virtual world, and social-oriented players are motivated by the need to socialize with other players through gaming.Objective: This study aimed to (1) quantitatively synthesize the growing body of literature to systematically examine the discrepancies in the magnitude of associations between various components of gaming motivation and IGD and (2) examine the moderating role of cultural dimension on the association between escapism gaming motivation and IGD.Methods: We conducted a systematic search of multiple databases between 2002 and 2020. Studies were included if they (1) included quantitative data, (2) used measures assessing both gaming motivation and IGD, and (3) contained sufficient information for effect size calculation.Results: The findings revealed IGD to have a stronger association with achievement motivation (r=0.32) than with immersion (r=0.22) or social motivation (r=0.20), but the strongest such association was found to be with escapism motivation (r=0.40), a subcomponent of immersion motivation. Our cross-cultural comparison further showed a stronger association between escapism motivation and IGD in studies conducted in individualistic (vs collectivistic) regions.Conclusions: This meta-analysis highlights the importance of acknowledging the discrepancies among different components of gaming motivation with respect to their role in the development of IGD, as well as the potential cultural variations in the strength of such associations.

We present a new high-pressure x-ray photoelectron spectroscopy system dedicated to probing catalytic reactions under realistic conditions at pressures of multiple bars. The instrument builds around the novel concept of a “virtual cell” in which a gas flow onto the sample surface creates a localized high-pressure pillow. This allows the instrument to be operated with a low pressure of a few millibar in the main chamber, while simultaneously a local pressure exceeding 1 bar can be supplied at the sample surface. Synchrotron based hard x-ray excitation is used to increase the electron mean free path in the gas region between sample and analyzer while grazing incidence <5° close to total external refection conditions enhances surface sensitivity. The aperture separating the high-pressure region from the differential pumping of the electron spectrometer consists of multiple, evenly spaced, micrometer sized holes matching the footprint of the x-ray beam on the sample. The resulting signal is highly dependent on the sample-to-aperture distance because photoemitted electrons are subject to strong scattering in the gas phase. Therefore, high precision control of the sample-to-aperture distance is crucial. A fully integrated manipulator allows for sample movement with step sizes of 10 nm between 0 and −5 mm with very low vibrational amplitude and also for sample heating up to 500 °C under reaction conditions. We demonstrate the performance of this novel instrument with bulk 2p spectra of a copper single crystal at He pressures of up to 2.5 bars and C1s spectra measured in gas mixtures of CO + H₂ at pressures of up to 790 mbar. The capability to detect emitted photoelectrons at several bars opens the prospect for studies of catalytic reactions under industrially relevant operando conditions.

Recent years have witnessed quite a number of worldwide efforts for fabricating CdSe/TiO₂ nanotube arrays (CdSe/TNTAs) nanocomposites; however, the construction of a well-defined CdSe/TNTAs binary nanostructure for versatile photocatalytic and photoelectrochemical applications still poses a big challenge. In this work, a hierarchically ordered CdSe/nanoporous TiO₂ nanotube arrays (CdSe/NP-TNTAs) hybrid nanostructure was fabricated through a facile electrochemical deposition strategy. The combined structural and morphological characterizations show that the CdSe ingredients, consisting of clusters of quantum dots, were uniformly assembled on the inner and outer surfaces of the NP-TNTAs framework. It was demonstrated that the CdSe/NP-TNTAs heterostructure could be utilized as an efficient photoanode for photoelectrochemical water splitting; moreover, it could be used as a multifunctional photocatalyst for photoredox applications, including the photocatalytic oxidation of organic dye pollutants and the selective reduction of aromatic nitro compounds under visible light irradiation. Furthermore, photoelectrochemical and photocatalytic mechanisms over the CdSe/NP-TNTAs heterostructure were elucidated. In addition, the predominant active species during the photocatalytic process were systematically explored and unequivocally determined. It is hoped that this work could promote further interest in the fabrication of various one dimensional NP-TNTAs-based composite materials and their applications to photoelectrochemical water splitting and photocatalytic selective redox applications.

Subsurface oxygen has been proposed to be crucial in oxide‐derived copper (OD‐Cu) electrocatalysts for enhancing the binding of CO intermediates during CO₂ reduction reaction (CO₂RR). However, the presence of such oxygen species under reductive conditions still remains debated. In this work, the existence of subsurface oxygen is validated by grazing incident hard X‐ray photoelectron spectroscopy, where OD‐Cu was prepared by reduction of Cu oxide with H₂ without exposing to air. The results suggest two types of subsurface oxygen embedded between the fully reduced metallic surface and the Cu₂O buried beneath: (i) oxygen staying at lattice defects and/or vacancies in the surface‐most region and (ii) interstitial oxygen intercalated in metal structure. This study adds convincing support to the presence of subsurface oxygen in OD‐Cu, which previously has been suggested to play an important role to mitigate the σ‐repulsion of Cu for CO intermediates in CO₂RR.