1wileyonlinelibrary.com them technologically important in a wide range of potential applications. [11,12] This promise has motivated intense research efforts seeking to develop general routes for synthesizing HCSs.Currently, the major approaches for the production of HCSs rely on templating methods. For example, monodisperse silica [13][14][15] or polyester microspheres [16,17] can be used as sacrificial hard templates, because they are readily available in a wide range of sizes. However, the synthesis procedure is complicated, as these hard templates need to be synthesized beforehand and then a carbon precursor needs to be coated on the surface of the templates, after which the template still needs to be removed as well. Hydrothermal reduction, [18] emulsion processing, [19] and selfassembly approaches [20][21][22][23][24] have also been reported for synthesizing HCSs. However, all of these approaches have some kind of disadvantage, such as low yields, or a time-consuming or complex fabricating process, that greatly limit their practical applications. More challengingly, little success has been achieved in realizing particle engineering in HCSs especially at the millimeter-length scale and to develop a processing technology for large-quantity production, both of which are essential to bring many promising applications of HCSs to reality. To this end, uniform hollow spheres with high mechanical strength are desirable, but the fabrication of such HCSs remains very challenging to date.Herein, we demonstrate a general, template-free, phase-separation approach, in which the liquid-liquid, phase-inversion process and the gas-foaming process are coupled for the first time, for a fast and continuous processing of macroscopic and mechanically robust HCSs. The phase-inversion process is a standard technique for preparing porous polymeric membranes used in membrane-separation processes. [25] In this fast and simple process, a concentrated polymer solution is immersed in a non-solvent bath and a solvent-non-solvent exchange leads to phase separation. [26,27] Here, we modified the phase-inversion process by dropping a polymer solution droplet into a nonsolvent coagulation bath, which could exchange solvent and non-solvent across the interface, and thus lead to a rapid precipitation at the surface of the droplet. Coupled with gas foaming
Macroscopic and Mechanically Robust Hollow Carbon Spheres with Superior Oil Adsorption and Light-to-Heat Evaporation PropertiesJianguo Zhou, Zhenlong Sun, Mingqi Chen, Jitong Wang, Wenming Qiao, Donghui Long,* and Licheng Ling Hollow carbon spheres (HCSs) represent a special class of functional materials, to which intense interest has been paid in the fields of materials science and chemistry. A major problem with these materials is the lack of sufficient particle engineering and mechanical strength for practical applications and the difficulty of up-scaling. Herein, we report a general, template-free, phaseseparation approach, in which the liquid-liquid phase-inversion process and a gas-...
