Concentration-Mediated Shape Evolution of Palladium Nanocrystals and Their Structure-Electrocatalytic Functionality

We reported a new insight into electrochemical shape evolution of Pd nanocrystals by controlling the concentration of Pd precursor, while the lower (EL) and upper (EU) potential limits of the square-wave potential were optimized at −0.8 and 0 V, respectively. It was found that the ratio (R) of the growth rate in the ⟨100⟩ to that of the ⟨111⟩ on a crystal increased with the concentration of PdCl2 getting higher in the reaction, leading to the shape transformation of Pd polyhedron from cubes to truncated octahedra, and finally to octahedra. The electrooxidation performances of CO and formic acid over the as-synthesized Pd polyhedrons were in the order of octahedra < truncated octahedra < cubes, indicating that the electrocatalytic activities of Pd polyhedrons were highly sensitive to the surface structure.