Reduced graphene oxide-wrapped La_0·8Sr_0·2MnO₃ microspheres sensing electrode for highly sensitive nitrite detection

An electrochemical nitrite sensor based on perovskite oxides La_0·8Sr_0·2MnO₃ (LSM) microspheres-decorated reduced graphene oxide (rGO) composite was presented to take the merit of the excellent electrocatalytic activity of the LSM and the large surface area of rGO. The content of rGO has been finely adjusted and the electrochemical sensor employing 15 wt% rGO has shown an ultralow nitrite detection limit of 0.016 μM and a high sensitivity of 0.041 μA μM^-1 cm^-2 and 0.039 μA μM^-1 cm^-2 in the range of 2-100 and 100-5000 μM, respectively. In addition, the proposed electrode shows good selectivity, reproducibility and stability, suitable for detection of nitrite at various pH values. The sensor was used to determine the nitrite level in environmental water samples with acceptable relative error, demonstrating its feasibility for practical environmental monitoring.