The heavy metal ion pollution of hexavalent chromium (Cr(Ⅵ)) in water is serious in China. An electrochemical sensor for hexavalent chromium (Cr(Ⅵ)) detection is proposed based on graphene nanomaterial. The graphene nanomaterial modified gold electrode (rGO/Au) was prepared by using the method of electrochemical reduction of graphene oxide (GO). The surface morphology and structure of rGO/Au were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM) technologies. The direct electrocatalytic reduction of Cr(Ⅵ) on the surface of rGO/Au was studied by using electrochemical methods such as square wave voltammetry (SWV)

cyclic voltammetry (CV) and linear sweep voltammetry (LSV)

etc. The preparation conditions were optimized which include GO reduction potential and reduction time

as well as the detection parameters

such as detection potential

pH and concentration of electrolyte. Without preconcentration step

the linear relationship between Cr(Ⅵ) concentrations and current responses on the rGO/Au was investigated by using amperometry method. The experimental results showed that graphene nanomaterial has electrocatalytic activity for Cr(Ⅵ) reduction. A good linear relationship between Cr(Ⅵ) concentrations and current responses was obtained from 5 to 2000 μg·L-1

with a low detection limit of 0.5 μg·L-1 (S/N ≥ 3). The modified electrode was resistant to some common metal interference ions

such as Cr(Ⅲ)

Ni(Ⅱ)

Cu(Ⅱ)

Mg(Ⅱ) and Mn(Ⅱ). And the response current decreased less than 10% compared to the initial value after 11 successive measures

which showed a relative good stability. The advantages of the proposed electrochemical sensor are simple

fast

friendly environmental and reusable

which made it possible to apply the sensor for rapid detection of Cr(Ⅵ) in water.