Shape-dependence in seeded-growth of Pd-Cu solid solution from Pd nanostructure towards methanol oxidation electrocatalyst
Lianxi Si, Hui Li, Yu Zhang, Donghao Zhang, Xiaowei An, Mengmeng Yao, Yuanyuan Shao, Jesse Zhu, Shi Hu
Abstract
Ultrathin Pd nanosheets (NSs) have great advantages in catalysis due to their large specific surface area and high percentage of under-coordinated atoms. However, the electrochemical performance still can be improved via composition-controllable growth of their solid solution. Herein, seeded alloying strategy was proposed to synthesize Pd-Cu solid solution from Pd NSs and Pd-Cu nanostructures with tunable molar ratios obtained by changing the amount of Cu precursor. As compared to the pristine Pd NSs, the Pd-Cu solid solution shows significantly enhanced methanol oxidation reaction (MOR) performance over those of Pd NSs and homemade Pd/C as the incorporation of Cu weakens the adsorption of CO intermediate on Pd in the MOR process. The choice of template is pivotal to the growth, as a shape-dependent behavior could be identified in the alloying of Cu with Pd nanosheets enclosed by {111} and {100} facets, Pd nanocubes enclosed by {100} facet, and Pd nano-tetrahedrons enclosed by {111} facet. The Pd-Cu solid solution with tunable composition can only be obtained from Pd NSs and the shape-dependent alloying process is mainly determined by the diffusion barrier and the minimum diffusion depth of the different facets.