Mo₂C/NCNTs nanocomposite with reconstructed interface for simultaneous electrochemical detection of dopamine, uric acid and ascorbic acid

A reconstructed Mo₂C/NCNTs interface was developed for simultaneous AA, DA, and UA sensing. • Ni removal enlarged mesoporous channels and exposed more accessible Mo₂C active sites. • Mo valence modulation promoted interfacial charge transfer and electrocatalytic oxidation. • Mo₂C/NCNTs/GCE delivered resolved oxidation peaks with low detection limits. • The sensor showed good selectivity, stability, and applicability in urine and serum samples. The simultaneous electrochemical determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) is important for biological analysis, but it remains challenging because of their close oxidation potentials and coexistence in complex samples. Herein, a reconstructed Mo₂C/NCNTs interface was developed as an efficient sensing platform through a pyrolysis–acid etching strategy. During pyrolysis, Ni nanoparticles promoted the in situ growth of nitrogen-doped carbon nanotubes (NCNTs), while Mo species were converted into Mo₂C, producing a closely integrated Ni/Mo₂C/NCNTs precursor. Subsequent selective removal of Ni generated Mo₂C/NCNTs with preserved tubular architecture, enlarged mesoporous channels, increased pore volume, exposed Mo₂C active sites, and redistributed Mo valence states. These structural and electronic features improved analyte diffusion, interfacial charge transfer, and electrocatalytic oxidation. The Mo₂C/NCNTs-modified glassy carbon electrode exhibited well-resolved oxidation peaks and enhanced current responses for AA, DA, and UA. The detection limits were 3.2 μM for AA, 0.11 μM for DA, and 0.15 μM for UA. The sensor also showed good selectivity, repeatability, reproducibility, and long-term stability. Satisfactory recoveries obtained in urine and serum samples further confirmed its applicability for practical analysis. This work provides an effective interface-regulation strategy for constructing Mo₂C-based electrochemical sensors for multi-analyte detection in biological matrices Download: Download high-res image (200KB) Download: Download full-size image