超薄钯铜纳米片组装纳米花的构建及其氧还原性能

Engineering ultrathin PdCu nanosheets-composed nanoflowers with high catalytic activity for oxygen reduction reaction

在原子水平上精确调控电催化剂的组成是增强其氧还原(ORR)性能的有效途径。本文采用简单的一步溶剂热还原法制备了由不同PdCu组成的超薄双金属纳米片自组装而成的三维(3D)合金纳米花(Pd_(1)Cu_(x) NCFs)。利用透射电子显微镜(TEM)、扫描透射电子显微镜-能谱仪(STEM-EDS)、X射线粉末衍射(XRD)和X射线光电子能谱(XPS)等手段系统表征了Pd_(1)Cu_(x) NCFs的形貌、晶体结构及成分。相比于传统二维(2D)纳米材料,Pd_(1)Cu_(x) NCFs丰富的快速传质路径、较高的Pd原子利用效率和更强的PdCu双金属间协同作用使得其在碱性介质中表现出增强的ORR性能。另外,本文还研究了Pd、Cu前体用量对ORR性能的影响。结果显示,Pd、Cu前体摩尔比为1∶0.5时,催化剂(Pd_(1)Cu_(0.5)NCFs)在碱性介质中ORR活性和电化学稳定性最佳。其半波电位E_(1/2)(0.937V)远高于商业Pt/C(0.851V);在加速循环1000次扫描后,E_(1/2)几乎没有变化,说明其稳定性优异;0.90V电势下,Pd_(1)Cu_(0.5) NCFs的质量比活性为1.09A/mg,是商业Pt/C的14.5倍。

Rationally controlling the composition of electrocatalysts at the atomic level is proved to be an effective way to improve their catalytic performance towards oxygen reduction reaction(ORR).Here,PdCu ultrathin nanosheets-composed three-dimensional(3D)nanoflowers(Pd_(1)Cu_(x) NCFs)with different compositions were prepared by a facile one-pot solvothermal reduction.The morphology,crystal structure and composition of catalysts were characterized by TEM,STEM-EDS,XRD,XPS,etc.Compared with traditional twodimensional nanomaterials,their abundant routes for fast mass transport,high Pd atom utilization efficiency as well as the synergistic effect of PdCu bimetal endowed Pd_(1)Cu_(x) NCFs with enhanced ORR performance under alkaline condition.In addition,the effect of the dosage of Pd and Cu precursors on the ORR performance was studied.Electrochemical measurement results indicated that the optimal catalyst(Pd_(1)Cu_(0.5)NCFs,the molar ratio of Pd/Cu precursor was 1∶0.5)exhibited the best ORR performance.A halfwave potential(E_(1/2))of 0.937V in alkaline medium was obtained,which was higher than that of commercial Pt/C(0.851V).Electrochemical accelerated durability test results showed that the Pd_(1)Cu_(0.5) NCFs could endure at least 1000 cycles with negligible activity decay,suggesting their excellent stability.At 0.90V,the mass activity of Pd_(1)Cu_(0.5) NCFs could achieve 1.09A/mg,which was 14.5 times higher than that of commercial Pt/C.