CoxNi1−x double hydroxide decorated graphene NPs for simultaneous determination of dopamine and uric acid

DA and UA, both have definite physiological activity, and several severe diseases of human beings are related to these biomolecules. Through a facile hydrothermal process, nickel-cobalt double hydroxide decorated graphene (CoxNi1−x(OH)2/G) was synthesized for the simultaneous determination of DA and UA. In CoxNi1−x(OH)2, Co(OH)2 creates defect and reduces the charge transfer resistance of Ni(OH)2 electrode, as well as actively participates in the redox reaction. These defects act as superior active sites and significantly improved the electronic and crystalline structure of CoxNi1−x(OH)2. In CoxNi1−x(OH)2/G, graphene reduces the aggregation of CoxNi1−x(OH)2 and increased the electroactive surface area and electrical conductivity of the nanocomposites. As a result, the enzyme-free biosensor showed well defined peak-to-peak separation for the simultaneous determination of DA and UA without interfering with each other. At the optimum conditions, the as-prepared sensor provided wide linear ranges from 0.1 to 750 µM and from 0.25 to 925 µM for DA and UA, respectively. The limit of detections was calculated as 43 and 97 nM, with better sensitivities of 343.71 and 132.96 µA mM−1 cm-2 for DA and UA, respectively. Furthermore, desirable results in urine sample analysis and no significant effect of interfering substances proved CoxNi1−x(OH)2/G as an effective electrochemical sensor.