Electrochemically Sensing of Trichloroacetic Acid with Iron(II) Phthalocyanine and Zn-Based Metal Organic Framework Nanocomposites

Rapid and accurate determination of disinfection by-products (DBPs) has become an emerging need for environmental monitoring and has yet to be realized in electrochemical sensors with metal organic framework (MOF)-based materials. In this study, a highly sensitive electrochemical sensor for trichloroacetic acid (TCAA) detection based on iron(II) phthalocyanine (PcFe) and a Zn-based metal organic framework (ZIF-8) composite is fabricated. As an electrode material, ZIF-8 possesses a large surface area and porous structure, which exhibits high absorbability; meanwhile, PcFe (II), as the sensing element, undergoes a reduction process from PcFe (II) to PcFe (I) during the sensing process. In the presence of TCAA, PcFe (I) is reoxidized by TCAA, which shifts the reaction equilibrium and accelerates the electron transfer on the electrode interface. By analyzing the reduction current of PcFe (II), the quantitative detection of TCAA is realized. The sensor shows a limit of detection (LOD) of 1.89 nM, which is superior to other reported TCAA sensors, as well as a high sensitivity (826 mu A/mu M). Moreover, the good selectivity and stability of this sensing platform demonstrate its capability and promise in determination of trace DBPs. The reported sensor provides a new strategy for electrochemical detection of DBPs and could expand the applications of MOFs in emerging technologies for monitoring contaminants.