富缺陷Pd纳米粒子制备及催化甲醇电催化氧化性能

Preparation of Pd nanoparticles with rich defects and its electrocatalytic oxidation of methanol

摘要:

以Pd(NO3)2?2H2O为原料，在V(无水乙醇)∶V(水)＝1∶4混合溶剂中构建十二烷基硫酸钠（SDS）胶束模板，采用超声辐射技术制备富缺陷Pd纳米粒子（Pd-NPs），采用TEM、HRTEM、XRD、XPS和UV-Vis等对其微观形貌和结构进行表征。将Pd-NPs作为电催化剂，探究其在碱性介质（KOH）中对甲醇氧化反应（MOR）的电化学行为。结果表明，Pd-NPs粒径为(21.7±3.6) nm，其具备晶界、晶格错位、晶格膨胀、晶格扭曲等晶格缺陷，可以为MOR提供丰富的活性位点；Pd-NPs的电化学活性表面积（ECSA）为62.42 m2/g，在浓度均为1.0 mol/L的KOH和CH3OH混合溶液中的质量活度高达2474 mA/mg，是商业Pd/C（153 mA/mg）的16.17倍，经500圈循环伏安（CV）后，其质量活度保持率为82.00% ；Pd-NPs在MOR计时电流（CA）测试3600 s时，其 比活度为0.11 mA/cm2 。Pd的d波段中心向上移动，提高了吸附物对Pd的吸附能力，从而激活Pd-NPs表面，增强了其催化能力。

Abstract:

Using Pd(NO3)2?2H2O as the raw material, sodium dodecyl sulfate (SDS) micelles templates were constructed in a mixed solvent with a volume ratio of anhydrous ethanol to water at 1:4. Rich-defect palladium nanoparticles (Pd-NPs) were then prepared through ultrasonic irradiation technology. TEM, HRTEM, XRD, XPS, and UV-Vis were employed to characterize their micromorphology and structure. The Pd-NPs were utilized as electrocatalysts to investigate their electrochemical behavior towards the methanol oxidation reaction (MOR) in alkaline media (KOH). The results indicated that the Pd-NPs had a particle size of (21.7±3.6) nm and exhibited lattice defects such as grain boundaries, lattice dislocations, lattice expansions, and lattice distortions, which could provide abundant active sites for MOR. The electrochemical active surface area (ECSA) of the Pd-NPs was 62.42 m2/g, and their mass activity reached 2474 mA/mg in a mixed solution of 1.0 mol/L KOH and CH3OH, which was 16.17 times higher than that of commercial Pd/C (153 mA/mg). After 500 cycles of cyclic voltammetry (CV), the mass activity retention rate of the Pd-NPs was 82.00%. During the chronoamperometry (CA) test for MOR over 3600 s, the specific activity of the Pd-NPs was 0.11 mA/cm2. The upward shift of the d-band center of Pd enhanced the adsorption capacity of adsorbates towards Pd, activating the surface of the Pd-NPs and augmenting their catalytic ability.