A bifunctional MoS2/SGCN nanocatalyst for the electrochemical detection and degradation of hazardous 4-nitrophenol

Abstract

Herein, we reported the dual functions of molybdenum disulfide/sulfur-doped graphitic carbon nitride (MoS₂/SGCN) composite as a sensing material for electrochemical detection of 4-NP and a catalyst for 4-NP degradation. The MoS₂ nanosheet, sulfur-doped graphitic carbon nitride (SGCN) and MoS₂/SGCN were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) spectroscopy and X-ray photoelectron spectroscopy (XPS). Electrochemical characterization of these materials with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in 1 mM K₄[Fe(CN)₆]^3-/4- show that the composite has the lowest charge transfer resistance and the best electrocatalytic activity. The limit of detection (LOD) and the linear range of 4-nitrophenol at MoS₂/SGCN modified glassy carbon electrode (MoS₂/SGCN/GCE) were computed as 12.8 nM and 0.1 - 2.6 μM, respectively. Also, the percentage recoveries of 4-NP in spiked tap water samples ranged from 97.8 - 99.1 %. The electroanalysis of 4-NP in the presence of notable interferons shows that the proposed electrochemical sensor features outstanding selectivity toward 4-NP. Additionally, the results of the catalytic degradation of 4-NP at MoS₂/SGCN show that the nanocatalyst catalyzed the transformation of 4-NP to 4-aminophenol (4-AP) with a first-order rate constant (k) estimated to be 4.2 ×10^-2 s^-1. The results of this study confirm that the MoS₂/SGCN nanocatalyst is a useful implement for electroanalytical monitoring and catalytic degradation of the hazardous 4-NP in water samples.