Top-down chemical etching to complex Ag microstructures

Abstract

Complex silver (Ag) crystals were crystallized by a technically flexible top-down chemical etching method in a solution phase. Microscale shaped Ag particles were first grown via a galvanic displacement of Ag on commercial Nb metal foil. The metastable Ag precursor was chemically active in solution containing NO₃⁻ and HF, readily crystallizing complex Ag microstructured crystals by a HNO₃-assisted etching. Insights are gained into the functions of HF and the mechanisms of generating large quantities of anisotropically shaped particles in the solution-phase. The crucial influences of HF concentration and reaction time on the morphology of Ag microstructures have also been established. This current top-down chemical route provides an extremely simple, mild, and effective recipe to crystallize Ag, which is also possible to expand to grow more metal crystals with controlled structures and particle morphologies.