1：Experimental Design and Method Selection:

The study involves preparing a 3D nanohybrid of carbon nanohorns (CNHs) and carbon nanotubes (CNTs) via ultrasonication for electrochemical sensing of PCNB, utilizing cyclic voltammetry (CV) and differential pulse voltammetry (DPV) for detection.

2：Sample Selection and Data Sources:

Real water samples were used to test the method's applicability, with PCNB concentrations measured after dilution in phosphate buffer solution (PBS).

3：List of Experimental Equipment and Materials:

Glass carbon electrode (GCE), CNTs, CNHs, ethanol, H2SO4, HNO3, phosphate buffer solution (PBS), ultrasonicator, transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) equipment.

4：Experimental Procedures and Operational Workflow:

CNTs were pretreated with H2SO4 and HNO3, then mixed with CNHs in ethanol and ultrasonicated. The mixture was stirred, filtered, washed, and dried. The nanohybrid was cast on GCE, dried, and used for electrochemical measurements in PBS with pre-absorption and sensing steps.

5：Data Analysis Methods:

Data were analyzed using DPV and CV to measure peak currents, with optimization of pH, nanohybrid amount, and accumulation time. Linear regression was used for calibration, and detection limit was calculated.