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-1cm−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. •A new strategy to induce the 3D assembly of MOFs on organic substrates.•Combination of gas phase and liquid phase growths leads to firm attaching.•Hierarchical 3D structure with vast active sites for high sensitivity.