New Insight into Single-Crystal Silver Dendrite Formation and Growth Mechanisms

Single-crystal silver dendrite structures, which possess a high surface area along with narrow gaps and sharp edges, have been widely explored as surface enhanced Raman scattering substrates and for catalytic and biosensing applications. With one of the simplest galvanic reactions, the reaction of AgNO3 with Cu, Ag dendrites can easily be produced. Here, we report new findings about this reaction and dendrite growth mechanisms. A series of experiments revealed a much more complicated reaction mechanism: metal Ag could form through reduction of Ag+ by intermediate nitrite (NO2-) ions inside the solution on a surface away from Cu. It was also found that Ag dendrites developed through a particle-mediated growth process. This new reaction mechanism can be utilized to generate completely freestanding, pure, and clean single-crystal Ag dendrites at room temperature within a few minutes.