Confined photoreaction in nano-engineered multilayer microshells

Nano-engineered multilayer microshells (microcapsules) as nano/microreactors are expected to expand the capabilities of confined photoreaction occurring in shell walls and in shell interiors and to explore new functionalities of application. The basis for optical reactions in multilayer microshells is their tailored wall components and particular properties originated from the permeability and stability of shell walls in response to external stimuli. This review aims at describing recent developments on the photochemical behaviors of photofunctionalized shell walls, mainly focusing on photocontrollable wall permeability by visible illumination. Apart from these, the photocatalytic reaction in spatially confined microshells is also reviewed, with an emphasis on recent advances in the visible light-assisted degradation of defined dye pollutants in the homogeneous or heterogeneous photo-Fenton system. The photoreaction mechanism occurring in the shells is also discussed. Finally, we have addressed some of the perspectives and challenges for the potential future development of microshells as photoreactors and applications based on these systems.