Hierarchical Core–Shell Structure of 2D VS₂@VC@N-Doped Carbon Sheets Decorated by Ultrafine Pd Nanoparticles: Assembled in a 3D Rosette-like Array on Carbon Fiber Microelectrode for Electrochemical Sensing

The development of two-dimensional (2D) nanohybrid materials with heterogeneous components in nanoscale and three-dimensional (3D) well-ordered assembly in microscale has been regarded as an effective way to improve their overall performances by the synergistic coupling of the optimized structure and composition. In this work, we reported the design and synthesis of a new type of hierarchically core–shell structure of 2D VS₂@VC@N-doped carbon (NC) sheets decorated by ultrafine Pd nanoparticles (PdNPs), which were vertically grown on carbon fiber (CF) and assembled into a unique 3D rosette-like array. The resultant VS₂@VC@NC-PdNPs modified CF microelectrode integrated the structural and electrochemical properties of the heterogeneous hybridization of core–shell VS₂@VC@NC-PdNPs sheets with a unique rosette-like array structure, and gave rise to a significant improvement in terms of electron transfer ability, electrocatalytic activity, stability, and biocompatibility. Under the optimized conditions, the VS₂@VC@NC-PdNPs modified CF microelectrode demonstrated excellent electrochemical sensing performance towards biomarker hydrogen peroxide (H₂O₂) including a high sensitivity of 152.7 μA cm^–2 mM^–1, a low detection limit of 50 nM (a signal-to-noise ratio of 3:1), as well as good reproducibility and anti-interference ability, which could be used for the real-time in situ electrochemical detection of H₂O₂ in live cancer cells and cancer tissue. The remarkable performances of the proposed nanohybrid microelectrode will have a profound impact on the design of diverse 2D layered materials as a promising candidate for electrochemical biosensing applications.