An ultrasensitive electrochemical sensor fabricated with porphyrin-based PCN-224/MWCNT and AuNPs for wide-range and low-level detection of phenolic isomers

A novel electrochemical sensing platform was constructed based on a porphyrinic MOF (PCN-224), multi-walled carbon nanotubes (MWCNTs), and gold nanoparticles (AuNPs). The PCN-224/MWCNT composite was first synthesized via a one-pot solvothermal method, followed by the deposition of AuNPs on its surface. The porous structure of PCN-224， the excellent conductivity of MWCNTs, and the catalytic activity of AuNPs collectively enhanced electron transfer efficiency and enabled highly selective recognition of dihydroxybenzenes exemplified by catechol(CC) and hydroquinone (HQ). The resulting PCN-224/MWCNT@AuNPs modified electrode simultaneously quantified HQ and CC across broad linear ranges of 1–1800 μM (HQ) and 1–1100 μM (CC), with extremely low limit of detection of 65.6 nM and 85.6 nM, respectively. The electrochemical sensor further exhibited outstanding long-term stability, exceptional repeatability, and robust anti-interference capability. Validated in real environmental samples, its quantification results align closely with those obtained by conventional HPLC, underscoring its high reliability for practical applications. This work provides an effective strategy for applying MOF-based hybrid materials in environmental electrochemical sensing.