Ultrathin Sulfur-Doped Graphitic Carbon Nitride Nanosheets As Metal-Free Catalyst for Electrochemical Sensing and Catalytic Removal of 4‑Nitrophenol

Graphene-like sulfur-containing graphitic carbon nitride (S-GCN) nanosheets were successfully prepared and thoroughly characterized. A simple synthetic method by a thermal condensation approach was reported for the preparation of S-GCN with trithiocyanuric acid (TCA) as precursor. The electrochemical performances of the 4-nitrophenol (4-NP) sensors were assessed by cyclic voltammetry (CV), amperometry, and differential pulse voltammetry (DPV). Ultrathin S-GCN nanosheets have been employed to enhance electrocatalytic activity, showing remarkable electrochemical behavior toward 4-NP. We thus obtained a wide linear response range from 0.05 to 90 μM, a relatively low detection limit (0.0016 μM), and excellent sensitivity in 0.1 M acetate buffer (ABS, pH 5.5), surpassing the existing modified electrodes in the literature. Moreover, the fabricated S-GCN electrode is selective in the presence of many potentially interfering species. As a result, the S-GCN contains (C with N and S) heteroatoms that probably induced the higher electrocatalytic activity and electrical conductivity behavior toward 4-NP. Besides, the structural defect to generate more active sites on the surface of S-GCN that could boost the fast electron transfer is provoked during the reduction of 4-NP. As a consequence, it is probably sensitive enough for quantitative detection of 4-NP in real samples. S-GCN was also applied to the hydrogenation of 4-NP by NaBH4 under ambient conditions. Thus, implementation of S-GCN nanosheets offers the advantages of simplicity, reliability, durability, and low cost.