Nanoarchitectonics of nest-like Co3O4 nanowires embedded nitrogen-doped graphene aerogel as electrochemical sensing platform for Pb2+ and Cd2+ trace detection

Abstract

Nano Co3O4 embedded nitrogen-doped graphene aerogel (Co3O4@NGA) was directly prepared by one-pot hydrothermal synthesis method with ammonia water acting as both precipitant of Co3O4 and nitrogen source of nitrogen-doped graphene aerogel (NGA). This novel method leaved out the calcination process which was necessary for most methods to prepare Co3O4 nanomaterials. The effects of hydrothermal temperature on both morphologies and Pb2+/Cd2+ electrochemical detection performances of Co3O4@NGA were explored. As the hydrothermal temperature rising from 140 °C to 200 °C, the shapes of Co3O4 changed from nanoparticles to nanowires and then to nanoflowers, and nest-like Co3O4 nanowires were architected on NGA sheets at 180 °C. The electrochemical sensor based on the optimized Co3O4@NGA-180 exhibited low limit of detection (LOD) for Pb2+ (7.2 nM) and Cd2+ (10.06 nM) and high sensitivity for Pb2+ (10.51 μA·μM−1) and Cd2+ (8.053 μA·μM−1). The excellent performances were attributed to the synergistic effect of Co3O4 nanowires and porous NGA, which leaded to the fast electrochemical reaction rate in the detection process. Moreover, the Co3O4@NGA-180/GCE sensor had excellent selectivity, repeatability and stability, and could be used to detect traces of Pb2+ and Cd2+ in real water sample.