Copper-cobalt dual-site on N-doped carbon nanotube with dual-promoted synergy for glucose electrochemical detection

Doping specific active sites and accelerating the decisive step of glucose catalysis to construct highly active glucose sensing electrochemical catalysts remains a major challenge for glucose sensing. Herein, we report the detailed design of Cu–Co dual active site N-doped carbon nanotube (CuCo-NCNTs) obtained by electrodeposition modification, programmed warming and calcination for electrochemical glucose detection. In the CuCo-NCNTs material system, Cu serves as the main active site for glucose sensing. Co with good adsorption of hydroxyl groups acts as the site providing hydroxyl groups to provide oxygen source for Cu oxidized glucose sensing. The synergistic effect between the two active sites in the Cu–Co system and the abundant micro-reactive sites exposed by carbon nanotubes greatly ensure the excellent electrocatalytic performance of glucose oxidation reaction. Therefore, CuCo-NCNTs have good electrocatalytic performance with a sensitivity of 0.84 mA mM−1 cm−2 and a detection limit of 1 μM, and also have excellent stability and specificity. DFT calculations elucidate the decisive steps of H-atom removal in the oxidation of glucose by Cu active site N-doped carbon nanotube (Cu-NCNTs) and Co active site N-doped carbon nanotube (CuCo-NCNTs) materials, illustrating the role of oxygen source provided by hydroxyl group adsorption in the electrochemical sensing process of glucose, thus demonstrating that the electrochemical sensing signal of glucose can be effectively enhanced when cobalt species that readily adsorb hydroxyl groups are introduced into the materials.