Strategy for Highly Sensitive Electrochemical Sensing: In Situ Coupling of a Metal–Organic Framework with Ball-Mill-Exfoliated Graphene

A highly sensitive electrochemical sensing system is developed via in situ integration of Cu-based metal–organic frameworks (Cu-BTC, BTC = 1,3,5-benzenetricarboxylic acid) and high-conductivity ball-mill-exfoliated graphene (Cu-BTC@GS) by a simple method. The as-synthesized Cu-BTC@GS hybrids display remarkably enhanced electrochemical activity due to the synergistic effect resulting from the integration. Compared to those of the pristine GS, the introduction of Cu-BTC nanoparticles leads to significant improvement in the surface area and porosity, as revealed by the nitrogen adsorption–desorption analysis. In addition, the oxidation behavior of nicotinamide adenine dinucleotide studied using the rotating ring disk electrode further reveals a superior electron-transfer rate constant (k) for the composite, indicating higher catalytic ability. Moreover, double potential step chronocoulometry of biomolecules (xanthine and hypoxanthine) and phenolic pollutants (bisphenol A and p-chlorophenol) reveals that the prepared composite possesses greatly enhanced adsorption properties, resulting in much higher response signals and detection sensitivity. Benefiting from the superior reactivity, a highly sensitive electrochemical sensing platform for wide targets is successfully fabricated. It was used in the analysis of plasma, urine, and receipt and wastewater samples, and the results were highly consistent with those obtained by high-performance liquid chromatography. We believe that this study provides an effective strategy for the construction of high-performance electrochemical sensing systems.