Simple immersion to prepare a Zn/Ag biomimetic superhydrophobic surface and exploring its applications on SERS

A very simple method for fabricating a superhydrophobic substrate was proposed. Zn foil was first polished and then immersed into an AgNO3 solution to obtain a silver-coated surface (Zn/Ag), which resulted in the formation of micro/nano-structures. After this substrate was immersed into a solution of 1-dodecanethiol, it exhibited superhydrophobic and low adhesion properties with a high contact angle (up to 167°) and a very low sliding angle (<2°) (Zn/Ag superhydrophobic surface). This inexpensive and facile process provides a feasible approach to the large-scale production of superhydrophobic surfaces. To better investigate the potential applications for this superhydrophobic surface, a series of surface-enhanced Raman scattering (SERS) spectra were collected as the volume of a drop that was supported on the surface of the substrate decreased. The SERS signal of the molecules in the drop changed regularly, first increasing and then decreasing in intensity, and we achieved the strongest SERS signal using this procedure, which can be utilized to improve the detection limit to a certain degree. This substrate has great potential for applications in highly sensitive SERS assays.