Hollow silica nanomaterials (HSNs) have attracted noticeable
attention because of their excellent biocompatibility, easy
surface functionalization accessibility, good chemical inertness,
and thermal stability.1−8 They have been used in diverse fields
including drug delivery, sensing, catalysis, and large biomolecular
release.9−11 The approaches for synthesizing HSNs can
be broadly divided into two categories: hard templating12−16
and soft templating.17−19 The hard-templating method
normally needs a layer of the desired materials coated on the
surface of the template core, followed by the selective removal
of the template. This approach has been widely used and
proven to be effective for the synthesis of hollow nanomaterials
with controllable shell thickness. However, tedious and
complicated procedures are usually required, which are
sometimes expensive and unsuitable for large-scale synthesis.
Many efforts have been devoted to developing self-templating
methods. In the soft-templating method, no additional
templates are needed, and therefore it may have the advantage
of a simple synthetic process and better scalability. For example,
Wang and Zeng applied a novel microemulsion system to
synthesize hollow silica nanoparticles, in which 1-dodecanethiol
served as an oil phase in the “oil-in-water” emulsion and a soft
template for the hollow interior. Moreover, the central space of
the SiO2 spheres was tunable by varying the amount of DDT.20