Rational electrochemical design of hierarchical microarchitectures for SERS sensing applications

Electrochemical deposition has been widely used to prepare conformal coatings but has rarely been used to design well-defined micro/nanostructures. Here we report electrochemical synthesis of complex, hierarchical inorganic microarchitectures simply via programming the applied potential waveforms. We identify two distinct electrochemical growth modes—the stacking mode and the flattening mode—under different potential waveforms. We demonstrate how these growth modes can work individually or cooperatively to design previously inaccessible microarchitectures. Each specific potential waveform corresponds to a specific microarchitecture, allowing us to prepare a rich library of microarchitectures. The designed microarchitectures can be converted into other materials by simple redox-potential-driven chemical reactions. We preliminarily studied the applications of converted nanoporous silver microscale torpedoes as high-performance surface-enhanced Raman spectroscopy (SERS) sensing substrates. The reported method opens up a new concept to design complex inorganic microarchitectures with promising applications in metamaterials, chemically or magnetically propelled microrobotics, and miniaturized devices.