Covalent organic framework-Pd complex derived Pd/N-doped honeycomb-like carbon nanocomposites for electrochemical detection of dihydroxybenzene isomers

An effective electrochemical sensing interface with fast electron and mass transfer and good catalysis is required to discriminate isomers such as hydroquinone (HQ) and catechol (CC). Herein, a macroporous covalent organic framework (COF)-Pd complex was first prepared by combining the unique properties of a N,O-rich COFTAPB-DA and template method, and then converted into a honeycomb like N-doped carbon supported Pd composite (Pd/NC) for simultaneous detection of HQ and CC. Binding of Pd2+ to COF and removal of polymethyl methacrylate spheres as pore-forming template were achieved by simply one-step mixing in dichloromethane (DCM) before calcination, which are different from previous preparation approaches of porous carbon composite, where harsh etching process and complicated surface modifications are required. The sensing interface constructed with this Pd/NC combined merits of N-doping, macroporous carbon and supported Pd catalyst shows greatly accelerated mass and electron transfer and high catalysis for the oxidation of CC and HQ. The detection limits are 0.73 nM and 0.92 nM, and linear ranges are 2.2 nM-38 μM and 2.8 nM-38 μM, respectively. Good selectivity and reproducibility were also obtained for real sample analysis. Such approach can be used to fabricate functional interface material for electrochemical sensing and catalysis.