Co-embedded N-doped hierarchical carbon arrays with boosting electrocatalytic activity for in situ electrochemical detection of H2O2

In this work, self-supporting hierarchical Co-embedded N-doped carbon structures composed of leaf-like carbon sheets arrays and interconnected carbon nanotubes (CNTs) were synthesized on carbon cloth (CC) via dicyandiamide-assisted pyrolysis. The resultant composite is abbreviated as CC/Co@C-CNTs, in which Co nanoparticles are embedded both in carbon sheets and the tips of CNTs. The characterizations proved the hierarchical three-dimensional structure, large electroactive surface area of 4.71 cm(-2), fast electron transfer, abundant Co/Co-N-x active sites, and synergistic effect between Co/Co-Nx species and CNTs in the CC/Co@C-CNTs-800-0.10 electrocatalyst. Benefiting from these unique superiorities, the CC/Co@C-CNTs-800-0.10 freestanding electrode exhibits excellent sensing performances of H2O2. It possesses a high sensitivity (388 mu A mM(-1) cm(-2)), fast response within 4 s, low detection limit (0.27 mu M, S/N = 3) and wide linear range (0.40 mu M-7.2 mM). More importantly, the freestanding electrode can be used to in situ detect H2O2 released from MDA-MB-231 cells and HeLa cells. This work provides a new design of nonenzymatic electrochemical sensing platform for amperometric determination of H2O2 in biological environment, which has great potential in cancer diagnosis, environmental monitoring and food analysis.