Macroporous Graphene Thin Films as Electrochemical Electrodes: Enhancing the Sensitivity for Detection of Metal Ions

A macroporous graphene thin films coated on ITO substrates (MGTFs@ITO) have been developed as electrodes for the electrochemical detection of heavy metal ions. The MGTF@ITO electrodes were characterized by scanning electron microscopy, Raman spectroscopy and contact angle measurements. The results demonstrated that the MGTF@ITO has a high specific area with robust macroporous framework and a hydrophilic surface. The cyclic voltammetry and electrochemical impedance spectroscopy using MGTFs@ITO as electrochemical electrodes indicated enhanced currents at the redox peaks, enlarged electrochemical surface area and a decreased charge transfer resistance. Based on these outstanding properties, the MGTF@ITO electrodes exhibited excellent stripping performace for the analysis of Ag(I) with a detection limit of 0.005 μg L-1. The high sensitivity of the MGTF@ITO electrodes can be ascribed to the well defined macroporous framework, high electrical conductivity, high specific area and good wettability. The MGTF@ITO electrodes were further demonstrated applicable to the simultaneous determination of Zn(II), Cd(II), Pb(II), Cu(II) and Ag(I) ions with outstanding sensing performance.