Electrocatalytical Applications Based On Nanoporous Noble Metals

In recent years, nanoporous metal materials with good conductivity and high specific surface area have been extensively studied due to their potential applications in catalysis and separation. They can be used as an ideal electrode model on the study of the electrocatalysis and electrochemical sensors. In this thesis, nanoporous Pt/Au alloys, nanoporous gold leaf made by dealloying and PB modified NPGL were used as electrodes for electrocatalysis. The electrocatalysis and electrochemical detection of glucose, hydrogen peroxide, ascorbic acid, nitrite and oxalic acid on such nanoporous metal materials have been studied.(1) PtAu Alloys with uniform structure and different compositions (Pt4Au1, Pt1Au1, Pt1Au4) were obtained by dealloying from Pt/Au/Cu alloys. The new nanoporous Pt/Au alloys were used as anode to study its catalytic activity for electro-oxidation of glucose. It was found that Pt1Au4 NPA had the best catalytic activity for electro-oxidation of glucose among the three nanoporous Pt/Au alloys. In addition, the electrocatalytic oxidation of glucose was studied in acidic, neutral and alkaline systems. The concentration of glucose was proportional to peak current by use of potentiostatic method in the alkaline system.(2) Nanoporous gold leaf with high specific area and large adsorptive capacity was prepared by free dealloying method from Au/Ag alloy. Because of the features of NPGL, we can carry out the electrodetection of NO2- and OA in solutions by electrochemical method. Compared with the bare glassy carbon electrode, and bulk gold electrode, the NPGL exhibited excellent electrocatalytic activity toward nitrite oxidation. While pH value of the solution increased, the oxidation peaks of NO2- and gold gradually overlapped. Under the optimized conditions, the linear range for the determination of nitrite was 1μM to 1 mM with a detection limit of 1μM. In addition, there was a good linear relationship between peak current with the concentration in the range of 0.01～16 mM and the detection limit of 1μM for OA.(3) Prussian blue nanoparticles were immobilized onto the nanoporous gold leaf by electrodeposition. We studied the electrochemical characteristics of the modified electrode and the electrochemical detection of H2O2 and AA on the modified electrode. The modified electrode obviously improved the stability of PB and exhibited strong response to H2O2 and AA in a broad pH range. Under the best experiment condition, the modified electrode had a good linear relation to electrochemical detection of H2O2 and AA from 1μM to 5 mM.