Sensitive detection of 4-nitrophenol based on pyridine diketopyrrolopyrrole-functionalized graphene oxide direct electrochemical sensor

Abstract

For highly sensitive detection of 4-nitrophenol (4-NP) in the environment, a novel pyridine diketopyrrolopyrrole-functionalized graphene oxide (PDPP–GO) composite was constructed for the first time by an improved Hummers' method. Herein, PDPP was completely dissolved in sulfuric acid (6 mol L⁻¹) and reacted with GO, promoting PDPP evenly adhering to the GO surface. Moreover, the specific surface area increased from 15.51 to 22.033 m² g⁻¹. Infrared spectroscopy and X-ray photoelectron spectroscopy simultaneously demonstrated that PDPP was bound to GO by the strong intermolecular hydrogen bonding and π–π stacking conjugation. During the cyclic voltammetry test, the PDPP–GO coated glassy carbon electrode (PDPP–GO/GCE) direct electrochemical sensor gave expression to the best electrocatalytic activity for 4-nitrophenol detection than GO/GCE and bare GCE. Under optimization conditions, the as-prepared PDPP–GO/GCE sensor brought out remarkable sensitivities of 18.54 (0.5–50 μM) and 6.61 μA μM⁻¹ cm⁻² (50–163 μM) in the linear detection of 4-NP. Besides, a low detection limit of 0.10 μM, reliable long-term stability, excellent selectivity, and reproducibility were obtained. In the real sample test, the PDPP–GO/GCE demonstrated sensitive and reliable determination.