In situ growth of ZIF-67-derived nickel-cobalt-manganese hydroxides on 2D VCT MXene for dual-functional orientation as high-performance asymmetric supercapacitor and electrochemical hydroquinone sensor.

Designing dual-functional electrode materials for supercapacitors and pollutant sensors has attracted great interest from researchers for urgent demand in green energy and the environment. In this work, a novel electrode material VCT@NiCoMn-OH was successfully constructed for dual-functional orientation via a two-step synthesis strategy, in which the NiCoMn-OH with a three-dimensional (3D) hollow structure was fabricated by employing ZIF-67 as a template and simple anion exchange and composited with the two-dimensional (2D) layered VCT MXene. The intercalation of NiCoMn-OH can effectively limit the self-accumulation of VCT MXene nanosheets and build a 3D cross-linked hollow structure, thereby broadening the ion transport channel, exposing more active sites of VCT@NiCoMn-OH, and simultaneously improving the conductivity of NiCoMn-OH. Benefiting from the unique 3D cross-linked hollow structure, the optimized VCT@NiCoMn-OH-20 electrode material exhibits an excellent specific capacitance of 827.45 C g at 1 A g. Furthermore, the electrode material has excellent capacitance retention of 88.44% after 10,000 cycles. Moreover, the VCT@NiCoMn-OH-20//AC ASC device displays a high energy density of 88.35 Wh kg as well as high power density of 7500 W kg during operation. Additionally, the VCT@NiCoMn-OH-20 exhibited excellent electrocatalytic performance in the detection of hydroquinone, including the low detection limit of 0.559 μM (S/N = 3) and the wide linear range of 2-1050 μM. Therefore, the prepared VCT@NiCoMn-OH-20 has great potential applications in the fields of supercapacitors and hydroquinone sensors.