Interfacial Charge Transfer in Phase-Coupled 1 T /2H MoS2@g-C3N4 Heterostructures: Platform for Ultrasensitive and Selective Detection of Chlorpyrifos in Real Vegetable Samples

Abstract Pesticide contamination has become a major global concern due to its persistence and negative consequences for human health and the environment. Chlorpyrifos is a widely used organophosphate pesticide that is particularly harmful because of its neurotoxic effects, which can disrupt the nervous system and lead to severe neurological disorders upon prolonged exposure. In this work, we report a phase-engineered 1T/2H-MoS2@g-C3N4 hybrid nanocomposite as an efficient electrochemical platform for the sensitive detection of chlorpyrifos. The novelty of the proposed work lies in integrating the metallic 1T and semiconducting 2H phases of MoS2 with a g-C3N4 framework, which provides abundant electroactive sites, enhanced electrical conductivity, and improved interfacial charge-transfer characteristics. The hybrid nanocomposite was synthesized through a simple hydrothermal approach and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV–Vis), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The fabricated sensor exhibited excellent electrochemical performance toward chlorpyrifos, achieving nanomolar detection limits with a wide linear range. Differential pulse voltammetry (DPV) revealed limits of detection (LOD) of about 0.004577 μM and 0.035665 μM at higher and lower concentrations, respectively. The sensor demonstrated rapid response within 10 s, good stability over 5–60 days, and reliable reusability across 15 cycles. Furthermore, negligible interference from coexisting species, along with satisfactory recoveries in real samples, demonstrates its selectivity and practical applicability. The synergistic combination of phase-engineered 1T/2H-MoS2 and g-C3N4 therefore provides an effective strategy for developing sensitive electrochemical sensors for chlorpyrifos monitoring in environmental and food samples.