Polyvinylpyrrolidone and graphene-modified hematite nanoparticles for efficient electrocatalytic oxidation of p-nitrophenol

Polyvinylpyrrolidone (PVP) and graphene (G)-modified iron oxides (Fe 2 O 3 -PVP-G) are prepared by a simple hydrothermal reaction. Their morphology and structure were examined and proved by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy. P-nitrophenol (p-NP) is a usual organic pollutant, which is highly toxic and difficult to decompose. Electrochemical reduction of p-NP is a widely used treatment, but the reduction products are still toxic. In this work, the electrochemical catalytic oxidation of p-NP was achieved on Fe 2 O 3 -PVP-G modified electrodes. Compared to pure Fe 2 O 3 , Fe 2 O 3 -PVP-G shows better catalytic performance, with a current density 10.4 times larger than that from Fe 2 O 3 . Electrochemical results verify that the improvement comes from the promotion of its activity and the favorable enrichment of p-NP with the help of the doped PVP and G. pH experiments indicate that p-NP is oxidized to aliphatic acid, which is non-toxic and environmentally friendly. Due to the protection of organic molecules, Fe 2 O 3 -PVP-G exhibits long-term stabilities on electrochemical oxidation on p-NP with the retention of 88.5% for 15 days. Our results also provide another perspective for studying electrocatalytic performances.