Pd-Pt NCNs电催化剂的制备及其甲醇氧化性能

Preparation and methanol oxidation performance of Pd-Pt NCNs electrocatalyst

为了提高直接甲醇燃料电池(DMFC)中电催化剂的催化活性和稳定性,以聚乙烯醇(PVA)作为还原剂和分散剂,采用水热法一步合成Pd-Pt NCNs电催化剂。通过调节溶液的pH值和Pd/Pt摩尔比制备出不同颗粒尺寸的Pd-Pt NCNs电催化剂;通过XRD、TEM、XPS手段对其形貌与结构进行了表征;通过循环伏安(CV)、计时电流(CA)测试方法研究不同pH值及Pd、Pt不同摩尔比下所制备的Pd-Pt NCNs电催化剂对甲醇催化氧化性能的影响。结果表明:随着溶液pH值的逐渐降低,所合成的Pd-Pt合金纳米颗粒尺寸逐渐减小,催化剂的甲醇氧化性能也随之提高;当溶液pH值为6、Pd/Pt摩尔比为4.4时,所制备的Pd4.4Pt1 NCNs-1催化剂颗粒均匀分散在PVA载体上,平均尺寸约为5.6 nm,在碱性氢氧化钾溶液中表现出优异的甲醇氧化催化活性和稳定性,对甲醇的氧化峰值电流密度达到482.14 A/g,是20%商业Pt/C(189.6 A/g)的2.5倍。

In order to improve the catalytic activity and stability of electrocatalysts in direct methanol fuel cells(DMFC),Pd-Pt NCNs electrocatalysts were synthesized by hydrothermal method using polyvinyl alcohol(PVA)as reducing agent and dispersant.Pd-Pt NCNs electrocatalysts with different particle sizes were prepared by adjusting the pH values of solution and the molar ratio of Pd,Pt.The morphology and structure of Pd-Pt NCNs were characterized by XRD,TEM and XPS.The effects of pH on the catalytic performance of Pd-Pt NCNs for methanol oxidation were investigated by cyclic voltammetry(CV)and chronoamperometry(CA).The results show that the size of the synthesized Pd-Pt nanoparticles decreases with the pH value decreases,but the methanol oxidation performance of the catalysts increases.When the pH value is up to 6 and Pd/Pt ratio is 4.4,the prepared Pd4.4Pt1 NCNs-1 catalyst particles are uniformly dispersed on the PVA supporter,and its average size is about 5.6 nm.It exhibites excellent activity and stability for methanol oxidation in alkaline potassium hydroxide solution.The catalytic peak current density for methanol oxidation reaches 482.14 A/g,which is 2.5 times that of 20%commercial Pt/C(189.6 A/g).