Sensitive and selective electrochemical detection of chromium(vi) based on gold nanoparticle-decorated titania nanotube arrays

Abstract

Owing to the severe toxicity and mobility of Cr(VI) in biological and environmental systems, it is of great importance to develop convenient and reliable methods for its detection. Here we report on a facile and effective electrochemical technique for monitoring Cr(VI) concentrations based on the utilization of Au nanoparticle-decorated titania nanotubes (TiO₂NTs) grown on a titanium substrate. It was found that the electrochemical reduction of Cr(VI) at the Ti/TiO₂NT/Au electrode exhibited an almost 23 fold improvement in activity as compared to a polycrystalline gold electrode, due to its nanoparticle/nanotubular heterojunction infrastructure. As a result, the Ti/TiO₂NT/Au electrode demonstrated a wide linear concentration range from 0.10 μM to 105 μM, a low detection limit of 0.03 μM, and a high sensitivity of 6.91 μA μM⁻¹ Cr(VI) via amperometry, satisfying the detection requirements of the World Health Organization (WHO). Moreover, the Ti/TiO₂NT/Au electrode exhibited good resistance against interference from coexisting Cr(III) and other metal ions, and excellent recovery for Cr(VI) detection in both tap and lake water samples. These attributes suggest that this hybrid sensor has strong potential in applications for the selective detection of Cr(VI).