Ultrasound-assisted synthesis of graphene@MXene hybrid: A novel and promising material for electrochemical sensing

To date, multiple graphene@MXene hybrids have been reported via various synthesis approaches, but almost all the graphene@MXene hybrids inevitably used the reduced graphene oxide that prepared by chemical oxidation/reduction method, which generally involved the complex and dangerous operation procedure, and the highly toxic chemical reagent. How to prepare graphene@MXene hybrid through a simple, safe and eco-friendly synthetic route is highly desired. Compared with traditional synthesis technology, ultrasound synthesis strategy displays the merits of simplicity, low cost and environment protection. Herein, MXene (Ti₃C₂T_x) nanoflakes coupled with graphene nanosheets (graphene@MXene) were prepared in N-methylpyrrolidone (NMP) by simple ultrasound-assisted liquid-phase exfoliation method for the first time. Besides, the effect of types of solvent with different viscocity, sonication temperature and sonication duration time on the property of graphene@MXene hybrids were systematacially investigated. It is found the liquid-phase exfoliated graphene owned excellent electron transfer ability and the MXene (Ti₃C₂T_x) nanoflakes possessed outstanding adsorption property, the as-synthesized graphene@MXene hybrid exhibited significant signal synergistic enhancement effect toward the oxidation of hazardous veterinary drug residue compound (chlorpromazine) and food additives (rhodamine B). Based on this, a novel and sensitive electrochemical sensor was fabricated, the linear detection ranges were 5 nM to 0.5 μM for chlorpromazine with sensitivity of 1090 µA μM⁻¹ cm⁻², and 10 nM to 2.5 μM for rhodamine B with sensitivity of 440 and 102.14 µA μM⁻¹ cm⁻². Besides, the detection limits were evaluated to be as low as 1.25 nM and 2.45 nM for chlorpromazine and rhodamine B, respectively.