The shape oscillations of drops in another fluid with or without surfactants has been analysed by normal mode expansions. The effects of surfactants are accommodated by considering the Gibbs elasticity, associated with the redistribution of surfactants, and a Boussinesq surface fluid with two surface viscosities. A general transcendental equation for the complex frequency of the free oscillations is derived. Explicit dispersion relations are given for fluids of small bulk viscosities and an interface of small, moderate, and large interfacial properties by a perturbation method. We have found that the oscillation always damps out faster for an interface exhibiting interfacial properties other than the interfacial tension, and the Gibbs elasticity is the most important parameter that alters the free-oscillation frequency and the damping constant. Moreover, the energy dissipation for an extensible interface can be much higher than that of an inextensible interface owing to the strong vorticity generated in the boundary layers.

The facile use of TBP generated notable improvements on perovskite crystallinity and photovoltaic performance of perovskite solar cells.

Catalyst-containing nanoreactors have attracted considerable attention for specific applications. Here, we initially report preparation of PtNi@SiO2 hollow microspheres based on confined catalysis. The previous encapsulation of dispersed Pt nanoparticles (NPs) in hollow silica microspheres ensures the formation of Pt@Ni coreshell NPs inside the silica porous shell. Thus, the Pt NPs not only catalyze the reduction of Ni ions but also direct Ni deposition on the Pt cores to obtain Pt@Ni core-shell catalyst. It is worthy to point out that this synthetic approach helps to form a patchlike or thick Ni coating on Pt cores by controlling the penetration time of Ni ions from the bulk solution into the SiO2 microspheres (0.5, 1, 2, or 4 h). Notably, the Pt@Ni core-shell NPs with a patch-like Ni layer on Pt cores (0.5 and 1 h) show a higher H2 generation rate of 1221-1475 H2 mL min(-1) g(-1)cat than the Pt@Ni NPs with a thick Ni layer (2 and 4 h, 920-1183 H2 mL min(-1) g(-1)cat), and much higher than that of pure Pt NPs (224 H2 mL min(-1) g(-1)cat). In addition, the catalyst possesses good stability and recyclability for H2 generation. The Pt@Ni core-shell NPs confined inside silica nanocapsules, with well-defined compositions and morphologies, high H2 generation rate, and recyclability, should be an ideal catalyst for specific applications in liquid phase reaction.