Metal Microcapsules Prepared via Electroless Plating at Liquid-Liquid Interface

Microfluidic fabrication of rattle shaped biopolymer microcapsules via sequential phase separation in oil droplets

Multilayer microcapsules containing a small particle within a larger capsule have recently attracted considerable attention owing to their potential applications in diverse fields, including drug delivery, active ingredient storage, and chemical reactions. These complex capsules have been fabricated using interfacial polymerization or seeded emulsion polymerization. However, these methods often require complex and lengthy polymerization processes, limiting their utility, particularly in biopolymer systems. This study introduces a simple and efficient approach for preparing rattle-shaped cellulose acetate (CA) microcapsules through sequential phase separation in droplets. We systematically examine the effects of various preparation parameters, including the amount of co-solvent, initial droplet size, and flow rates, and reveal that the incorporation of a co-solvent-ethyl acetate (EA)- in the dispersed phase significantly impacts the microcapsule morphology. Our findings demonstrate a transition from a core-shell to a rattle-shaped structure as the EA concentration increases. Furthermore, the initial droplet diameter and flow rates influence microcapsule formation-larger droplets and reduced continuous-phase flow rates favor the development of multi-layered structures. These results indicate that the formation mechanism of these rattle-shaped microcapsules arises from the establishment of a radial solvent concentration gradient and subsequent phase separation within the droplets, driven by kinetic rather than thermodynamic factors.

Advancing Inorganic Microcapsule Fabrication through Frozen-Assisted Interfacial Reactions Utilizing Liquid Marbles

Inorganic microcapsules (IMs) have gained significant attention as versatile platforms for delivering functional agents in various fields. Traditional template-dependent methods employing hard templates often involve complex and harsh template removal processes. Achieving IMs with diverse composition and structure remains challenging with current preparation strategies. Therefore, in this work, we have for the first time demonstrated an extremely facile and efficient liquid-marbles-based template approach for fabricating pure inorganic microcapsules via interfacial reaction in a mild aqueous solution. The water-water reaction interface is created by changing the wettability of the liquid marble (LM) surface through the icing-melting process. The composition and function of the inorganic shell could be easily adjusted by varying the inorganic reagent species of the interfacial reaction, the hydrophobic particle of the shell, and the reaction environment according to the specific requirements of the application field. Such an approach provides a flexible platform for material preparation.

Electroless Ni plated nanostructured TiO2 as a photocatalyst for solar hydrogen production

Herein, we have demonstrated a facile electroless Ni coated nanostructured TiO2 photocatalyst for the first time. More significantly the photocatalytic water splitting shows excellent performance for hydrogen production which is hitherto unattempted. The structural study exhibits majorly the anatase phase along with the minor rutile phase of TiO2. Interestingly, electroless nickel deposited on the TiO2 nanoparticles of size 20 nm shows a cubic structure with nanometer scale Ni coating (1-2 nm). XPS supports the existence of Ni without any oxygen impurity. The FTIR and Raman studies support the formation of TiO2 phases without any other impurities. The optical study shows a red shift in the band gap due to optimum nickel loading. The emission spectra show variation in the intensity of the peaks with Ni concentration. The vacancy defects are pronounced in lower concentrations of Ni loading which shows the formation of a huge number of charge carriers. The electroless Ni loaded TiO2 has been used as a photocatalyst for water splitting under solar light. The primary results manifest that the hydrogen evolution of electroless Ni plated TiO2 is 3.5 times higher (1600 μmol g-1 h-1) than pristine TiO2 (470 μmol g-1 h-1). As shown in the TEM images, nickel is completely electroless plated on the TiO2 surface, which accelerates the fast transport of electrons to the surface. It suppresses the electron-hole recombination drastically which is responsible for higher hydrogen evolution using electroless Ni plated TiO2. The recycling study exhibits a similar amount of hydrogen evolution at similar conditions which shows the stability of the Ni loaded sample. Interestingly, Ni powder loaded TiO2 did not show any hydrogen evolution. Hence, the approach of electroless plating of nickel over the semiconductor surface will have potential as a good photocatalyst for hydrogen evolution.