Exfoliated graphene-like carbon nitride in organic solvents: enhanced photocatalytic activity and highly selective and sensitive sensor for the detection of trace amounts of Cu2+

Abstract

Due to their unprecedented electronic, surface and optical properties, the atomic-thick graphene-like materials have aroused great interest. Compared with the bulk counterparts, the graphene-like material can not only enhance the internal properties, but also gives rise to new promising properties. Herein, the graphene-like carbon nitride (graphene-like C₃N₄) was synthesized via liquid exfoliation from the bulk graphitic carbon nitride (g-C₃N₄) in 1,3-butanediol (1,3-BUT) for the first time. And the graphene-like C₃N₄ was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), and X-ray photoelectron spectroscopy (XPS). The obtained graphene-like C₃N₄ exhibited a two-dimensional thin-layer structure with about 3–6 atoms thickness, a high specific surface area of 32.54 m² g⁻¹, increased photocurrent responses, improved electron transport ability and enhanced photocatalytic activity. The photocatalytic reaction for the organic dye methylene blue (MB) by the graphene-like C₃N₄ followed first-order kinetics. Moreover, the graphene-like C₃N₄ exhibited a higher apparent rate of 0.1262 min⁻¹, which was 3.1 times higher than that of the bulk g-C₃N₄ (0.0409 min⁻¹). The enhanced photocatalytic reaction was due to a high specific surface area and a larger bandgap (by 0.14 eV). The yield of the graphene-like C₃N₄ was up to ∼0.35 mg mL⁻¹. Moreover, the graphene-like C₃N₄ had a new property that it could be used as the sensor for trace amounts of Cu²⁺ determination, so the graphene-like C₃N₄ is a new but promising candidate for heavy metal ions (Cu²⁺) determination in water environment. Photoelectrochemical selective sensing of trace amounts of Cu²⁺ was also discussed.