Different Catalysts In Organic Electrolyte Electrocatalytic Properties Of Ammonia Oxidation

NH3 is widely used in the industry. However, NH3 is a kind of toxic gas. Even small amount of NH3 is very harmful to the human body. Thus, monitoring NH3 in the living and working environments is very important. Therefore, the development of the current type of electrochemical NH3 sensor with in situ measurement, low cost, high sensitivity and good selectivity has the important meaning.This thesis mainly investigated the catalysts with the high electrocatalytic performance and stability for the NH3 oxidation in the organic solvent. The amperometric NH3 sensor with the organic solvent was studied and assembled. Its performance for the NH3 measurement was carried out. The main results obtained are as follows:1. Comparison of the electrocatalytic performances of the Pt/C catalyst for NH3 oxidation in PC and PC/DME solventsIt was found that in the mixed electrolyte of PC and DME with low viscosity, the Pt/C catalyst electrode has the excellent electrocatalytic performance, the good sensitivity, good selectivity and short response time for the NH3 oxidation. In addition, the sensor is resistant to the high temperature and low relative humidity.2. The electrocatalytic performances of the carbon supported Pt-Ru catalyst electrodes with the different atomic ratio of Pt and Ru for the NH3 oxidation in the PC/DME solventThe Pt-Ru/C catalysts with the atomic ratio of 1:1,2:1,3:1 and 4:1 of Pt and Ru as well as 20% mass percentage of Pt-Ru alloy was prepared with THF complexing reduction method. It was found that in PC/DME solvent, the electrocatalytic activity and stability of the Pt-Ru/C catalyst electrode are increased with increasing the content of Ru. Thus, the electrocatalytic activity and stability of the Pt-Ru/C catalyst electrode with the atomic ratio of 1:1 are best. In addition, CO, NO and NO2 do not disturb the measurement of NH3, but H2S and SO2 obviously disturb the measurement of NH3.3. The electrocatalytic performances of the Ir/C and Pt-Ir/C catalysts for the NH3 oxidation in the PC/DME solventIt was found that in the PC/DME solvent, Ir/C catalyst has the excellent electrocatalytic activity for the NH3 oxidation, but it has low stability. Moreover the electrocatalytic stability of Pt-Ir/C catalyst for the NH3 oxidation is obvious better than that of the Ir/C catalyst.