Co-Doped ZnO Nanomaterials as a Novel Platform for Hydrogen Peroxide Biosensing

Co-doped ZnO nanomaterials have been synthesized successfully on indium tin oxide glass by direct electrochemical deposition using as a platform to immobilize horseradish peroxidase enzyme and to enhance the response of hydrogen peroxide. The crystal structures and morphology of Co-doped ZnO were characterized by X-ray diffraction and scanning electron microscopy, whereas surface electronic state and the element ratio were revealed by X-ray photoelectron spectroscopy measurements. Cyclic voltammetric and electrochemical impedance spectroscopy were carried out with the electrodes, and it was found that the Co-doped ZnO nanomaterials had good conductivity and fast electron transfer in electrocatalytic reduction. According to the amperometry response, a broad linear response was in the range of 0.05 to 1.15 mM and the detection limit was 13 mM at a signal-to-noise ratio of 3 (S/N=3) within 10 s at an applied working potential of -0.3V. The sensitivity and value for the electrode were 22.7 mA mM^-1 and 2.93 mM, respectively. The proposed biosensor was not affected by other pollutants and maintained nearly 90% of its original activity after a monthly storage. These results indicate that proper doping can improve electron transfer abilities of ZnO and enable this traditional semiconductor material to have better performance in sensing applications.