Potassium-doped graphene for simultaneous determination of nitrite and sulfite in polluted water

Potassium (K) doping plays a critical role in adjusting the electronic properties of carbon materials. In this work, K-doped graphene, as a new electrode material, was used to modify glassy carbon electrode (GCE) for the simultaneous determination of nitrite (NO2−) and sulfite (SO32−) under neutral conditions. The advantages of K-doped graphene/GCE are illustrated from comparison with the graphene/GCE, K-doped multi-walled carbon nanotubes (MWNTs)/GCE, MWNTs/GCE, graphite/GCE and bare/GCE for electrocatalytic and sensing applications. It exhibited a linear response over the concentration range from 0.5 μM to 3.9 mM, with a detection limit of 0.2 μM (S/N = 3) for NO2− and a corresponding linear range of 2.5 μM to 10.3 mM, with a detection limit of 1.0 μM (S/N = 3) for SO32−. The proposed sensor could be successfully applied in the simultaneous detection of residual NO2− and SO32− in polluted water accurately and precisely.

► Using potassium (K)-doped graphene as a novel electrode material.
► The K-doped graphene shows superior electrochemical activity for nitrite (NO2−) and sulfite (SO32−).
► The first time to conveniently achieve the simultaneous determination of NO2− and SO32− in polluted water.