Highly Controllable Fabrication of Gold Composite Nanostructures by Multiple Electroplating for High-Performance Electrochemical and Raman Scattering Measurements

Abstract

Morphology-controlled nanostructures are important functional materials in multidisciplinary research fields, such as sensing, imaging, catalysis, and energy harvesting. However, existing nanofabrication methods have limitations in terms of controllability, diversity, cost, and efficiency. Here, a novel nanofabrication approach is proposed to construct Au nanostructures with high controllability, cost-efficiency, and high-performance sensing and energy harvesting. The fabrication incorporates electric field-assisted hydrothermal growth of zinc oxide nanorods (ZnO NRs) with two-step gold electroplating. The ZnO NRs serve as a dissolvable template during the electroplating formation of gold nanostructures for eventually synthesizing pure gold nanostructures on electrodes. The synthesized gold nanostructures take unique composite shape of nanospheres (hundreds of nanometers) covered with tinier nanostructures (tens of nanometers) like floccules, grains, lamellas, or rods, which are highly controlled by regulating electroplating parameters. The gold composite nanostructures provide high-performance sensing and energy harvesting, such as enhanced electrochemical sensing interface (electric double-layer impedance decrease up to 97.1%), excellent surface-enhanced Raman scattering (SERS enhancement factor up to (Formula presented.)), and preferable visible–near-infrared light harvesting (absorptivity near to 90%). For the first time, the application of tumor cell photothermal therapy with nanostructured electrodes and in situ bimodal monitoring of single-cell impedance and SERS-based molecular expression during therapy is demonstrated.