Fabrication of rGO/MXene-Pd/rGO hierarchical framework as high-performance electrochemical sensing platform for...

A  nanocomposite of rGO/MXene-Pd/rGO with hierarchical structure based on Ti₃C₂T_x MXene, Pd nanoparticles, and reduced graphene oxide (rGO) was synthesized by a green approach. Ti₃C₂T_x MXene decorated with Pd nanoparticles (MXene-Pd) was prepared first. Then, graphene oxide (GO), MXene-Pd, and GO were coated on the surface of the glassy carbon electrode (GCE) in sequence. After each coating of the GO layer, the GO nanosheets were reduced to rGO electrochemically. The fabricated rGO/MXene-Pd/rGO hierarchical framework performs a pie structure with MXene-Pd as the stuffing and rGO nanosheets as the crust, which will be beneficial to the enhancement of its electrochemical sensing performance. As compared with other electrodes, the rGO/MXene-Pd/rGO/GCE exhibited higher electrocatalytic activity and better sensing performance for luteolin detection, with a wide linear range of 6.0 × 10^-10 to 8 × 10^-7 M and 1.0 × 10^-6 to 1.0 × 10^-5 M (oxidation peak potential E_pa = 0.34 V vs. SCE), a low detection limit of 2.0 × 10^-10 M, and a high sensitivity of 112.72 µA µM^-1 cm^-2. Moreover, the fabricated sensor also showed high selectivity, reproducibility, and repeatability toward the detection of luteolin. The real sample analysis for luteolin in honeysuckle was successfully carried out by rGO/MXene-Pd/rGO and verified with high-performance liquid chromatography (HPLC) analysis techniques with acceptable results. All the above tests indicate the promising application prospect of the rGO/MXene-Pd/rGO framework for luteolin detection in honeysuckle and other herbs containing luteolin.