A facile template synthesis of asymmetric gold silica heteronanoparticles

•Silica hemispheres containing gold nanoparticle cores have been synthesized.•We used a flat substrate as a template to confine the space where silica shells grow.•Silica shell thickness in the gold silica heterostructure could be controlled in a nanometer scale.•The heteronanoparticles allows selective etching of the core, giving hemispherical capsules.•The gold homodimers could be obtained by overgrowth of the core gold seeds.

Silica hemispheres containing gold nanoparticle cores have been synthesized via immobilization of gold nanoparticles on a substrate and site-selective growth of silica followed by removal of the hemispherical particles. The structure of these asymmetric heteronanoparticles allows selective etching or overgrowth of the core gold seeds, which results in the respective formation of hemispherical capsules or gold homodimers.

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