In this study, a new chemical modifier based on copper nitrate hydroxide-containing mesoporous silica decorated with a C3N4 framework (MSN/C3N4/CNH) was developed to design a modified sensor for the determination of clonazepam (CZP). The resulting composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), simultaneous thermal analysis (STA), Brunauer-Emmett-Teller (BET) and Barrett Joyner–Halenda (BJH) analyses. The fabricated electrochemical sensor which was designed with a new modified glassy carbon electrode (GCE) for CZP analysis, exhibits outstanding electrocatalytic activities toward the reduction of CZP. The results showed that significant sensitivity compared to existing methods improved with an excellent detection limit of 2.50 nmol L− 1 for the CZP detection, and the modified electrode has high activity toward the oxidation and reduction of CZP, with an oxidation peak around 0.32 V, and a lower reduction peak around − 0.78 V; at pH = 7.0. The effect of experimental and instrumental factors on the electrochemical sensor response was examined, and the cyclic voltammetric results confirmed the 4H+/4e− process in the electrochemical studies. Moreover, in differential pulse voltammetry, the reduction peak current was proportional toward the CZP concentration from 0.82 to 76.90 μmol L− 1, at optimum conditions. The modified electrode showed good reproducibility, and repeatability with relative standard deviation values of 2.7% and 1.2%, respectively. The proposed method can be applied as a simple, selective, and precise method to determine CZP drug in real samples, with satisfactory results.
