Rapid preparation of self-supported nickel-iron oxide as a high-performance glucose sensing platform

Nickel-iron based electrocatalysts that display a highly sensitive electrochemical response are promising candidates for non-enzymatic glucose sensors. In this work, we report a rapid (similar to 10 min) and controllable one-step electrodeposition of NiFeOx supported on nickel foam (NF) and carbon cloth (CC) as electrochemical glucose sensing platforms. Material characterization studies reveal that the as-electrodeposited NiFeOx is composed of tiny nanoparticles with a lower crystallinity degree and abundant oxygen vacancies. On the one hand, the lower charge transfer resistance allows NiFeOx/NF to achieve a fast charge transfer kinetics compared to pristine NF. On the other hand, NiFeOx/NF exhibits a larger double-layer capacitance (C-dl) and superhydrophilic surface state, which result in an increased electrochemical surface area and enhanced affinity to glucose molecules. Consequently, the NiFeOx/NF glucose sensor presents a better sensing response (sensitivity: 2320 mu A mM(-1) cm(-2) and the limit of detection: 0.094 mu M in the linear range from 0.1-2.1 mM), an excellent selectivity against interfering substances, and high stability for over three weeks. In addition, the electrodeposition-derived NiFeOx is able to detect glucose in actual samples and also shows a promising prospect in flexible devices. This work not only offers a fast fabrication of the NiFeOx electrode but also highlights the potential use of Ni-Fe oxides for enzyme-free glucose sensing.