Sensitive amperometric determination of hexavalent chromium using a gold nanoparticle-Ti3C2Tx MXene-poly(diallyldimethylammonium chloride)-reduced graphene oxide composite modified electrode

A gold nanoparticle (AuNP)-Ti 3 C 2 T x -MXene-poly(diallyldimethylammonium chloride) (PDDA)-reduced graphene oxide (rGO) composite was prepared for electrochemical detection of hexavalent chromium (Cr (VI)). Firstly, Ti 3 C 2 T x -MXene was prepared by HF etching of aluminum titanium-carbide (Ti 3 AlC 2 ), and AuNP-MXene composite was prepared by self-reduction method. Then, the PDDA functionalized rGO (PDDA-rGO) was prepared by hydrothermal reduction method. Finally, the AuNP-Ti 3 C 2 T x was assembled on PDDA-rGO by the electrostatic interaction, and an AuNP-Ti 3 C 2 T x -PDDA-rGO composite was obtained. The composition and morphology were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Raman spectroscopy. The electrochemical behavior of Cr (VI) on the composite modified electrode was studied carefully. The results showed that PDDA-rGO can be used as a good carrier to firmly load AuNP-Ti 3 C 2 T x by electrostatic interaction. The simultaneous introduction of AuNP and Ti 3 C 2 T x enhanced the electrochemical activity of the composite. Under the synergistic action of various components, the composite showed strong catalytic activity for the electrochemical reduction of Cr(VI). The linear range of amperometric detection of Cr(VI) was 2.0 × 10 −8 –1.1 × 10 −5  mol/L and 1.1 × 10 −5 –3.9 × 10 −4  mol/L. respectively. The detection limit is 1.0 × 10 −8  mol/L (S/N = 3). The composite electrode had the characteristics of low detection limit, high sensitivity and wide linear range, and can be used for quantitative determination of Cr (VI) in water samples.