Hierarchically Structured Nanoparticle Monolayers for the Tailored Etching of Nanoporous Silicon

Nanoporous silicon (NPSi) can be used in a wide range of applications including nanofiltration, thermoelectrics, photovoltaics, and catalysis. Metal-assisted chemical etching (MACE) is an electrochemical, solution-based NPSi fabrication process that relies on control over catalyst deposition to obtain the desired porous structure. In this paper, blade-casting is explored as a template-free, self-assembly deposition technique for MACE catalyst. Mixtures of silica (SiO2) and gold-core silica-shell nanoparticle (SiO2AuNP) catalysts are assembled by blade-casting, resulting in tunable hierarchical monolayers that, after MACE, produce >100 μm2 NPSi with ～20 nm pores