Atomic layer deposition-assisted fabrication of 3D Co-doped carbon framework for sensitive enzyme-free lactic acid sensor

As an important biomaterial, lactic acid (LA) widely exists in human blood and sweat. The development of enzyme-free LA sensors with high-sensitivity and low-cost remains a challenge. We present here a structure of Co-doped porous carbon film derived from zeolitic imidazolate framework-67 (ZIF-67) on 3D carbon frameworks through a pyrolysis process. The conformal coating of ZIF-67 film is realized by a combination of gas-phase and liquid phase growths with the assistance of an induction step from atomic layer deposited-ZnO nanomembrane. In the resultant hierarchical structure with large surface area, Co-doped porous carbon film is closely stacked and firmly attached to carbon skeleton to form Co-doped N-containing carbon framework (Co-NCF). Therein, the Co-doped porous carbon provides catalytic Co nanoparticle, while the carbon skeleton bridges the individual carbon nanoparticle to form a conductive pathway. When adopted as an enzyme-free LA sensor, the Co-NCF composite exhibits excellent electrochemical sensing property in terms of an ultrahigh sensitivity of 1108 μA mM -1 cm −2 at a liner range from 0.1 to 1 mM with a limit of detection of 13.7 μM. This work, therefore, presents an efficient strategy to prepare porous carbon structures toward new electrode materials in promising biomedicine systems.