Efficient, simultaneous, quantitative and qualitative detection of multiple phenols using highly water-stable Co2+-doped Cu–BTC as an electrocatalyst†

A rational design of water-stable and high-efficiency MOF-based electrocatalysts for achieving durable sensitive electrochemical sensors for pollution detection remains a great challenge. Herein, water-stable Co²⁺-doped Cu²⁺ and 1,3,5-benzene tricarboxylic coordination polymers (Cu–BTC@Co) were designed to construct a sensitive and durable electrochemical sensor for simultaneously detecting multiple hazardous phenols. Combining the Mulliken charges of H₂O and BTC, the mechanism for the water stability of Cu–BTC@Co was discussed. Intermolecular force (Cu–BTC and Cu–H₂O) and intramolecular force (π–π bond and COO–H₂O hydrogen bond) made Cu²⁺ coordination to BTC much stronger than water; thus, Cu–BTC@Co with strong stability in a water environment was achieved. Moreover, doping Co²⁺ into Cu–BTC not only improves the electron transfer efficiency of Cu–BTC but also enhances the catalytical efficiency of Cu–BTC. Combining the high-efficiency selective catalysis of Cu–BTC@Co and oxidation potential difference among multiple phenols, the Cu–BTC@Co sensor can achieve simultaneous, quantitative and qualitative detection of multiple phenols with good multicycle sensing performance. This study clarifies the mechanism of synthesizing water-stable MOFs and promotes the application of MOF-based sensors in the quantitative analysis of water pollutants.