The construction of CoP nanoparticles coated with carbon layers derived from core-shell bimetallic MOF for electrochemical detection of dopamine

•New, eco-friendly method for preparing CoP-based electrocatalyst was proposed.•CoP well coated with carbon layers was supported by carbon sphere.•CoP@C/NCS/GCE has ultra-high sensitivity (9.4 μA μM−1) for DA.•CoP@C/NCS/GCE/GCE is feasible to detect DA in diluted serum with good recoveries. Design of catalysts with unique structures in enhancing electrochemical activity and stability has still been pursued. An eco-friendly method for preparing CoP with improved electrochemical performances was proposed in this work. A novel P-doped bimetallic ZIF-67@ZIF-8 (ZIF-67@ZIF-8-P) was prepared as the precursor for constructing of CoP@C/NCS, in which CoP nanospheres coated with carbon layers (CoP@C for short) were well-dispersed on N-doped carbon spheres (NCS for short). P was strategically pre-introduced into ZIF-67@ZIF-8 for preparing of ZIF-67@ZIF-8-P through the selective phosphorylation on ZIF-8 shell. DA was selected to investigate the electrochemical properties of CoP@C/NCS. Glassy carbon electrode (GCE) modified by CoP@C/NCS exhibited excellent properties in detection of DA by square wave stripping voltammetry (SWV), that a high sensitivity of 9.4 μA μM−1, and low limit of detection of 0.03 μM. In addition, CoP@C/NCS showed enhanced performances on electrocatalytic oxidation of DA than that of CoP/C prepared based on ZIF-67 by the common phosphorization method reported in literatures. Moreover, a wide linear range from 5.0 μM to 400.0 μM was achieved at CoP@C/NCS/GCE by amperometric i-t. The practical application of CoP/NCS/GCE was evaluated by detection of DA in human serum. The satisfactory recoveries in diluted serum demonstrated the promising application of CoP@C/NCS.