One-pot solvothermal synthesis of lotus-leaf like Ni7S6/CoNi2S4 hybrid on carbon fabric toward comprehensive high-performance flexible non-enzymatic glucose sensor and supercapacitor

Due to increased attentions on diabetes mellitus, flexible and multifunctional electrodes toward glucose detection have been desired for the construction of a wearable glucose self-monitoring system (WGSS). Herein, bifunctional Ni-Co-S materials for energy storage and glucose detection were in situ synthesized on flexible carbon fabric (CF) by a novel one-pot solvothermal tactic with binary sulphur sources. It is found that a lotus-leaf-like nanostructure can be realized under the binary synergism of sulphur sources. Moreover, the composition, crystal phase, and deposition amount are affected by the molar ratio of the two sulphur sources. Under the optimum ratio of two sulphur sources, a dense coating composing of hierarchical Ni7S6/CoNi2S4 hybrid can be fabricated on CF. Such hierarchical and dense nanostructures of Ni7S6/CoNi2S4 on CF can provide rich reaction sites and strong support, making it an excellent flexible free-standing electrode for both the non-enzymatic glucose sensor (NEGS) and supercapacitor (SC). When served for NEGS, Ni7S6/CoNi2S4@CF reached the outstanding electrocatalytic activity toward glucose oxidation with a satisfactory sensitivity of 2053 mu A mM(-1) cm(-2) and a quite broad linear range response from 0.0001 to 7.08 mM. Besides, in the case of SC, the electrode exhibited super electrochemical properties with high areal specific capacity of 3.90 F cm(-2) at 1 mA cm(-2). More than that, the remarkable rate capability (2.84 F cm(-2) even at the high current density of 20 mA cm(-2)) and excellent cycle performance (capacitance retention of 100% at 30 mA cm(-2) after 5000 cycles) were attained at the same time, which is attributed to the special hierarchical morphology and dense nanostructures. When compared to the reported SC-NEGS bifunctional electrodes, Ni7S6/CoNi2S4@CF showed comprehensive high performance. Such great electrocatalytic performance demonstrated that Ni7S6/CoNi2S4 hierarchical nanostructure presents great potential for future use as flexible multifunctional electronic devices toward NEGS and SC.

Automated summary

In this study, bifunctional Ni-Co-S materials were successfully synthesized for energy storage and glucose detection, with hierarchical and dense nanostructures of Ni7S6/CoNi2S4 fabricated on flexible carbon fabric for non-enzymatic glucose sensor and supercapacitor applications, demonstrating excellent electrochemical properties.