A precise control of the size, density, and distribution of metal nanoparticles dispersed on functional oxide supports is critical for promoting catalytic activity and stability in renewable energy and catalysis devices. Here, we measure the growth kinetics of individual Co particles ex-solved on SrTi0.75Co0.25O3‑δ polycrystalline thin films under a high vacuum, and at various temperatures and grain sizes using in situ transmission electron microscopy. The ex-solution preferentially occurs at grain boundaries and corners which appear essential for controlling particle density and distribution, and enabling low temperature ex-solution. The particle reaches a saturated size after a few minutes, and the size depends on temperature. Quantitative measurements with a kinetic model determine the rate limiting step, vacancy formation enthalpy, ex-solution enthalpy, and activation energy for particle growth. The ex-solved particles are tightly socketed, preventing interactions among them over 800 °C. Furthermore, we obtain the first direct clarification of the active reaction site for CO oxidationthe Co-oxide interface, agreeing well with density functional theory calculations.

In photoelectrochemical (PEC) water splitting, BiVO4 is considered the most promising photoanode material among metal oxide semiconductors because of its relatively narrow optical bandgap and suitable band structure for water oxidation. Nevertheless, until now, the solar-to-hydrogen conversion efficiency of BiVO4 has shown significant limitations for commercialization because of its poor charge transport. Various strategies, including the formation of a heterojunction and doping of electron donors, have been implemented to enhance the charge transport efficiency; however, fundamental approaches are required for further enhancement. In this regard, we report the fundamental approach for BiVO4 thin film photoanodes by fabricating epitaxial oxide thin films with different crystallographic orientations for PEC water splitting. The crystalline anisotropy generally reveals distinct physical phenomena along different crystallographic orientations. In the same vein, in terms of the anisotropic properties of BiVO4, the electrical conductivity of BiVO4 is greater along the ab-plane than along the c-axis. Consequently, as the crystallographic orientation of the BiVO4 thin film changes from (001) to (010), the charge transport properties in the epitaxial BiVO4 thin film are significantly enhanced. Thus, at 1.23 VRHE, the photocurrent density of the epitaxial BiVO4 (010) thin film (2.29 mA cm–2) is much higher than that of the epitaxial BiVO4 (001) thin film (0.74 mA cm–2) because of significant enhancement in charge transport properties even for undoped BiVO4. These results strongly suggest that the growth of epitaxial BiVO4 thin films with specific crystallographic orientations has great potential to considerably improve the charge transport efficiency of photoanodes for solar water splitting.

This study examined the role of calcineurin, a major calcium‐dependent protein phosphatase, in dephosphorylating Ser‐9 and activating glycogen synthase kinase‐3β (GSK‐3β). Treatment with calcineurin inhibitors increased phosphorylation of GSK‐3β at Ser‐9 in SH‐SY5Y human neuroblastoma cells. The over‐expression of a constitutively active calcineurin mutant, calcineurin A beta (1–401), led to a significant decrease in phosphorylation at Ser‐9, an increase in the activity of GSK‐3β, and an increase in the phosphorylation of tau. Km of calcineurin for a GSK‐3β phosphopeptide was 469.3 μM, and specific activity of calcineurin was 15.2 nmol/min/mg. In addition, calcineurin and GSK‐3β were co‐immunoprecipitated in neuron‐derived cells and brain tissues, and calcineurin formed a complex only with dephosphorylated GSK‐3β. We conclude that in vitro, calcineurin can dephosphorylate GSK‐3β at Ser‐9 and form a stable complex with GSK‐3β, suggesting the possibility that calcineurin regulates the dephosphorylation and activation of GSK‐3βin vivo.

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