Preparation of Ni nanotube-modified electrodes via galvanic displacement on sacrificial Zn templates: Solvent effects and attempts for non-enzymatic electrochemical detection of urea

In this study, Ni nanotube-modified stainless-steel electrode (SSE\Ni-anodized) was prepared by galvanic displacement on tangled Zn nanowire-composed sacrificial template (SSE\Zn) followed by anodization in 1 M NaOH. The tangled Zn nanowires were electrodeposited from an amide-type room temperature ionic liquid (RTIL) 1-butyl-1-methypyrrolidinium bis((trifluoromethyl)sulfonyl)amide ([BMP][TFSA]) containing ZnCl2, and then galvanic displacement was conducted in the same RTIL with [NiCl4](2-). The process was unable to be reproduced by using water or choline chloride-ethylene glycol deep eutectic solvent (ChCI-EG DES) as the reaction media, indicating the unique properties of RTILs. The cations of RTILs are critical to successfully retaining the skeleton of Zn-nanowire-template. SSE\Ni-anodized showed high activity towards the oxidation of urea and possessed a detection limit of 3 mu M, a sensitivity of 902.8 mu A.mM(-1).cm(- 2), and a dynamic range of 1-20000 mu M. Most importantly, the electrode could be regenerated by anodization in 1 M NaOH to remove adsorbed urea without significantly altering the surface morphology and performance of the electrode. A low background current was achieved after the regeneration process, which is important for repeatedly using the same electrode in urea determination.