Fig. 3.

Products of wafer-catalyzed and templated reaction. (A) Scanning electron microscopy images depicting products formed from the hydrolysis and condensation of the gallium nitrate precursor catalyzed by the bifunctional wafer containing the nucleophilic (hydroxyl) and hydrogen-bonding (imidazole) termini (NP-HB surface). (Scale bar: 10 μm.) A 10-fold greater particle number density is observed on the hydroxyl lines than on the imidazole lines. (B) Energy-dispersive spectrometry mapping of condensate on the NP-HB biomimetic catalyst revealing the product, localized on the hydroxyl lines, rich in gallium and oxygen. (C) Higher-magnification imaging reveals a dense network of layered particles condensed upon hydroxyl-printed lines. (Scale bar: 1 μm.) (D) Substitution of either essential surface functionality (nucleophile or hydrogen-bonding amine) with a nonactive methyl group renders the surface hydrolytically inactive. (Scale bar: 10 μm.) (E) Particles from hydroxyl-terminated SAMs from C. (Scale bar: 50 nm.) (F) Sample removed after a short reaction time demonstrates significantly more condensed product at the SAM interface, with a substantial decrease in particle number density away from the interface. (Scale bar: 1 μm.)