Metal-free graphene-based nanoelectrodes for the electrochemical determination of ascorbic acid (AA) and p -nitrophenol ( p -NP): implication towards biosensing and environmental monitoring

Herein, a metal-free tyramine-functionalized graphene oxide (T-GO) electrocatalyst was used for the electrochemical determination of ascorbic acid (AA) and an organic pollutant specially substituted by a phenolic compound, i.e. , p -nitrophenol ( p -NP), in 1 M phosphate buffer solution at pH 7 as a model species. The cyclic voltammetry investigation of AA and p -NP has a significant role in biosensing and the management of industrial waste. Thus, the electrochemical detection of AA and p -NP was successfully achieved using the T-GO-modified GC electrode for the oxidation of AA at an onset potential of −0.03 V vs. SCE. A redox reaction occurred for the detection of p -NP at an onset potential oxidation peak (O1) of 0.047 V vs. SCE and reduction peaks (R1 and R2) at −0.62 V vs. SCE and 0.147 V vs. SCE, respectively. The stability and reproducibility of the T-GO-based electrocatalyst were outstanding for the detection of both AA and p -NP, which can be attributed to its improved active surface area after the functionalization of GO with tyramine.