Pt和Ir催化剂在中性电解液中对NH3电氧化性能

Effects of Pt and Ir Catalysts on Electrooxidation of NH_3 in Neutral Electrolyte

比较了Pt和Ir催化剂在中性NaClO4电解液中对NH3氧化的电催化活性和选择性。发现NH3和NH4OH在Pt和Ir催化剂上的电氧化性能相似,因而可用NH4OH代替NH3进行研究。NH4OH在Pt和Ir催化剂上氧化峰峰电流密度与NH4OH浓度呈很好的线性关系,因而Pt和Ir均能作为控制电位电解型NH3传感器的催化剂。当NH4OH浓度为0.013 mol/L时,NH3在Pt和Ir催化剂上的氧化峰分别位于0.4和0.8 V,NH4OH在Pt催化剂上的氧化峰峰电位负于在Ir催化剂上的,这是Pt催化剂的优点,但NH4OH在Ir催化剂上的氧化峰峰电流密度为Pt催化剂上的2.5倍以上,说明NH4OH在Ir催化剂上的检测灵敏度远高于在Pt催化剂上的。而且CO对NH3在Ir催化剂上的检测没有干扰,但在Pt催化剂上有明显干扰。因此,初步的研究结果表明,Ir催化剂较适用于定电位电解型的NH3电化学传感器的阳极催化剂。

The electrocatalytic activities and selectivities of Pt and Ir catalysts for the NH3 oxidation in neutral NaClO4 solution were compared. It was found that the electrooxidation of NH3 and NH4 OH at the Pt and Ir catalysts are similar. Thus, NH4 OH can be used to study instead of NH3. Both peak currents of the anodic peaks of NH4 OH at Pt and Ir catalyst electrodes are linearly proportional to the concentration of NH4 OH. Thus, both the Pt and Ir can be used as the catalysts of the potential fixed electrochemical NH3 sensor. When the concentration of NH4 OH is 0. 013 mol/L, the anodic peaks of NH4 OH at the Pt and Ir electrodes are located at 0. 4 and 0. 8 V, respectively, indicating that the potential of the anodic peak of NH4 OH at the Pt catalyst is more negative than that at the Ir catalyst and it is the advantage of the Pt catalyst. However, the current density of the anodic peak of NH4OH at the Ir catalyst is 2. 5 times larger than that at the Pt catalyst. Furthermore, CO does not disturb the measurement of NH4 OH at the Ir catalyst, but obviously interferes the measurement of NH4OH at the Pt catalyst. Therefore, the preliminary results indicate that the Ir catalyst is a suitable catalyst for the potential fixed electrochemical NH3 sensor.