Application of Ionic Liquid-Graphene-NiO Hollowsphere Composite Modified Electrode for Electrochemical Investigation on Hemoglobin and Electrocatalysis to Trichloroacetic Acid

In this present paper NiO hollowsphere was synthesized by a solvothermal method. Then it characterized by different methods including powder X-ray diffraction and scanning electron microscopy. NiO hollowsphere was further mixed with hemoglobin (Hb), ionic liquid and graphene (GR) to get a biocomposite, which was casted on carbon ionic liquid electrode. Spectroscopic data showed that Hb kept its native structure in the mixture. Direct electron transfer of Hb were investigated with a pair of well-defined quasi-reversible redox peaks appeared and the formal peak potential (E0') was got at -0.341 V (vs. SCE). The Hb modified electrode showed excellent electrocatalysis to trichloroacetic acid (TCA) reduction. Under the selected conditions the currents had a good linear relationship with TCA concentration from 1.5 to 10.0 mmol L-1 and the detection limit was 0.5 mmol L-1 (3σ). This Hb based electrode exhibited good stability and reproducibility, which could be used for third-generation electrochemical biosensor.