In situ growth of chrysanthemum-like NiCo2S4 on MXenes for high-performance supercapacitors and a non-enzymatic H2O2 sensor

Abstract

In this work, we developed a novel strategy to couple chrysanthemum-like NiCo₂S₄in situ-grown MXene hybrids into a three-dimensional (3D) sandwich architecture hybrid as an electrode material for high-performance asymmetric supercapacitors and non-enzymatic H₂O₂ sensors. In the 3D sandwich architecture hybrid, the NiCo₂S₄ particles were encapsulated by MXene layers, which enhanced the interlayer space of MXene, significantly improving the electrochemical properties. In particular, the MXene/NiCo₂S₄ 1 : 2 electrode achieved a specific capacitance of 1266 F g⁻¹ at 0.5 A g⁻¹ and maintained 95.21% of its initial value after 10 000 cycles. Furthermore, an asymmetrical supercapacitor was also fabricated using MXene/NiCo₂S₄ 1 : 2 as the positive electrode and activated carbon (AC) as the negative electrode (MXene/NiCo₂S₄ 1 : 2//AC), which exhibited exceptional electrochemical performance. MXene/NiCo₂S₄ 1 : 2//AC exhibited a large specific capacitance of 621 F g⁻¹ at 0.5 A g⁻¹ and energy density of 72.82 W h kg⁻¹ at a power density of 0.635 kW kg⁻¹. In addition, MXene/NiCo₂S₄ 1 : 2 was employed as a non-enzymatic sensor for the electrochemical detection of H₂O₂, which exhibited a high sensitivity of 0.267 μA μM⁻¹ cm⁻² and noteworthy low detection limit of 0.193 μM based on 3 signal-noise ratios. This research provides a facile route for the in situ growth of bimetallic sulfides on MXenes as electrode materials for energy storage and electrochemical detection.