Fabrication And Performance Of Non-Enzymatic Urea Sensor Based On Nanostructured Ni Materials

Nickel-based nanomaterials are widely used in electrochemical catalysis and sensors because of their low price,excellent stability and catalytic activity,but as the active materials of non-enzymatic urea sensor,the sensitivity and response speed still need to be improved.In this study,Ni-MOF and paper-based Ni-P nanomaterials were prepared,and electrochemical enzyme-free urea sensors with improved detection sensitivity,response speed and stability.Firstly,a nickel metal-organic framework material,Ni-MOF（BTC）,was fabricated by one-step hydrothermal method to construct an urea sensor with the detection range of 0.1-6 m M,the sensitivity of 152.5μA m M^-1 in the range of 0.1-2m M,the sensitivity of 92.7μA m M^-1 in the range of 2-6 m M,the lowest detection limit of 7μM,and the response time of 5 s.In addition,it has good anti-interference performance and stability.Characterization by SEM,XRD,XPS,BET and the like proves that the performance is due to the porous structure of the prepared material,which increases the specific surface area and provides more catalytic active sites.In order to improve the sensitivity of the urea sensor,a flexible porous cellulose paper was used as a base material to grow Ni-P nanomaterials on the surface thereof by a simple solution soaking and chemical bath method,achieving controllable regulation of different nanostructures.The urea sensor constructed by Ni-P nanoflower paper electrode exhibits the best electrochemical performance,including the highest sensitivity(683.46μA m M^-1 cm^-2 in the range of 0-1 m M and 1140μA m M^-1 cm^-2 in the range of 1-11 m M),the lowest detection limit of 12μM and the shortest response time of 3 s.Characterization by SEM,FT-IR,XRD,XPS,BET and the like proves that the performance is because the prepared Ni-P paper electrode combines the large specific surface area of the cellulose paper and the high catalytic performance of the Ni-P nanomaterial.In addition,the catalytic activities of Ni-P nanomaterials with various micro-morphologies on urea are ranked as follows:nanoflowers>nanowire microspheres>nanosheets>microspheres,which may be attributed to their different specific surface areas.