A new insight into the electrochemical growth of Ag nanodendrites without a strong electrolyte

Abstract

We have developed a simple and green electrochemistry technique to synthesize Ag nanostructures with a highly pure, crystalline and smooth surface, which takes place in a clean and slow reaction environment (just highly pure de-ionized water) without any chemical additives. Here, we report a new insight into the Ag nanodendrite (ND) synthesis via the developed electrochemistry without a strong electrolyte. It is found that Ag₂CO₃ nanospindles and AgNDs form in water and on a graphite negative electrode, respectively, when an Ag target is immersed in the highly pure de-ionized water under an external voltage, which is totally different from conventional electrochemistry. The reaction processes are investigated in detail both theoretically and experimentally. The results show that CO₂ from air plays a crucial role in the formation of AgNDs. CO₂ is dissolved into the de-ionized water to form HCO₃⁻, weak acid anions, which results in the formation of Ag₂CO₃. Then, Ag⁺ is reduced to metallic AgNDs on the negative graphite electrode. The AgND modified graphite electrode (AgND/GE) shows a significant improvement in the electroreduction of H₂O₂ compared to the bare graphite electrode. These investigations suggest that introducing a weak electrolyte in the electrochemical cell offers an alternative route to design and fabricate novel nanostructures for practical applications.