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ABSTRACTThe stability of the phase Pr3Pt4in a series of Pr42.9Pt57.1-xFex(x = 0, 1, 2, 3) alloys was investigated by using X-ray diffraction (XRD) and differential thermal analysis (DTA). It was found that the phase Pr3Pt4(3:4 phase) with Pu3Pd4-type structure formed in the Pr42.9Pt57.1-xFexalloy for x = 0 annealed at 1173 K for two weeks. However, the fraction of the 3:4 phase decreased rapidly with increasing x, and approached zero when x = 3. XRD and DTA results showed that the 3:4 phase decomposes gradually into the two neighboring phases PrPt (1:1 phase) and (Pr, Fe)Pt2(1:2 phase), and the decomposition temperature of the reaction 3:4 → 1:1 + 1:2 is shifted slightly to higher temperature with increasing x. The reason for this phase decomposition is briefly discussed by the preferential site occupation of Fe in Pr3Pt4.

•Spray drying method is an original method for preparing BiOCl photocatalyst.•The crystallinity of BiOCl prepared by the spray drying method is good.•The BiOCl photocatalyst synthesized by spray drying has a special morphology with hollow spherical structure.•BiOCl with large specific surface results an efficient separation and transport of photogenerated electron-hole pairs.•BiOCl has an efficient visible-light-driven photocatalysis.

We report on the size dependence of the Ag–Cu nano-alloy melting temperatures via differential scanning calorimetry (DSC) measurements of silica-coated Ag–Cu nanoparticles (NPs) and the thermodynamic modeling. Four Ag–Cu alloy NP samples with compositions ranging from Ag8Cu2to Ag5Cu5were prepared via NaBH4co-reduction and silica-coating. The experimental size dependence of melting temperature was obtained via UV–visible absorption spectra, transmission electron microscopy, and DSC. On the basis of the measured melting temperatures of the Ag–Cu nano-alloys in this work as well as the thermodynamic properties of the pure Ag and Cu NPs and Ag–Cu systems in literature, the theoretically calculated size dependence of Ag–Cu NP melting temperatures was then obtained via thermodynamic modeling of the Ag–Cu nano-system. Thermodynamically calculated size dependence of the melting temperatures for Ag–Cu alloy NPs shows a nonlinear function with respect to the inverse of the particle size and satisfactory agreement with experimental observations. This work establishes a methodology for determining the melting temperature as a function of size for different nano-alloy systems.

Nanoconfinement has been widely employed as a promising strategy to improve dehydrogenation kinetics, reversibility, and equilibrium pressure of complex metal hydrides. In this paper, we report a careful study of the influence of nanoconfinement on the reversible dehydrogenation property and reaction mechanism pathway of the 2LiBH4–MgH2composite system. Compared to the bulk 2LiBH4–MgH2composite, the 2LiBH4–MgH2confined in the mesoporous carbon (CMK-3) scaffold host exhibits the significantly enhanced dehydrogenation kinetics but meanwhile shows the serious loss of hydrogen capacity upon cycling, particularly in the first two cycles. Moreover, the observed dehydrogenation property is independent of the hydrogen back pressure. The combination analyses of XRD, FTIR, and NMR definitely detected the dominant Mg and B phases in the dehydrogenation products, suggesting the mainly individual desorption of MgH2and LiBH4in the confined 2LiBH4–MgH2system. This unfavorable change of the dehydrogenation reaction pathway would result in the poor reversibility, which is not expected for the combined hydride systems. These findings might provide renewed insight into the nanoconfinement effect on the hydrogen storage property for multiple phase combined systems.