In principle, incorporating nanoparticles into growing crystals offers an attractive and highly convenient route for the production of a wide range of novel nanocomposites. Herein we describe an efficient aqueous route that enables the spatially-controlled occlusion of gold nanoparticles (AuNPs)within ZnO crystals at up to 20 % by mass. Depending on the precise synthesis protocol, these AuNPs can be (i) solely located within a central region, (ii) uniformly distributed throughout the ZnO host crystal or (iii) confined to a surface layer. Remarkably, such efficient occlusion is mediated by a nonionic water-soluble polymer, poly(glycerol monomethacrylate)70 (G70), which is chemically grafted to the AuNPs; pendent cis-diol side-groups on this steric stabilizer bind Zn 2+ cations, which promotes nanoparticle interaction with the growing ZnO crystals. Finally, uniform occlusion of G70-AuNPs within this inorganic host leads to faster UV-induced photodegradation of a model dye.
Biominerals provide many wonderful examples of the incorporation of water-solublebiomacromolecules within various inorganic crystals, such as bones, teeth and seashells. [1] However, incorporating nanoparticles into inorganic crystals is much more challenging. [2] This is because crystallization normally favors impurity expulsion, rather than occlusion. [3] Nevertheless, various inorganic nanoparticles (e.g. Pt, Au, Fe3O4, quantum dots, etc) have been encapsulated into zeolites, [4] metal organic frameworks (MOFs), [5] and ionic crystals, [6] albeit typically at relatively low loadings. In related work, inorganic nanoparticles can also be incorporated into CaCO3 (calcite) [7] or Cu2O [8] respectively using a gel-trapping or confinement-based strategy.