Control of Reduction Kinetics to Form Palladium Nanocubes Enables Tunable Concavity

In spite of the advances in understanding how to prepare concave Pd nanocubes, the quantitative measurement on how the salt precursor reduction process impacts the product is still concealed. Herein, concave Pd nanocubes in distinct concavities have been prepared with an insight mechanistic study. Through the seed-mediated growth method, on the basis of as-synthesized cubic seeds of different sizes and by controlling the concentration of KOAc, the reduction rate of the Pd precursor is manipulated and the morphologies of concave nanocubes are regulated. The growth pathway of concave nanocubes from nanocubes can be divided into two stages, a nonselective growth period, where the growth rate of corners and edges are in balance, and a corner-specialized growth period, where corners are the main growth sites. The reduction kinetics of the Pd precursor has been discussed with the approximation for the reduction as a first-order reaction. It is found that the reduction rate constant of the precursor should be within an appropriate range to prepare Pd CNCs with controlled concavities. The fast precursor reduction process leads to the formation of concave cubes with low concavity, and the generation of small nanoparticles is prioritized.