Use of Reduction Rate as a Quantitative Knob for Controlling the Twin Structure and Shape of Palladium Nanocrystals

Abstract

Kinetic control is a powerful means for maneuvering the twin structure and shape of metal nanocrystals and thus optimizing their performance in a variety of applications. However, there is only a vague understanding of the explicit roles played by reaction kinetics due to the lack of quantitative information about the kinetic parameters. With Pd as an example, here we demonstrate that kinetic parameters, including rate constant and activation energy, can be derived from spectroscopic measurements and then used to calculate the initial reduction rate and further have this parameter quantitatively correlated with the twin structure of a seed and nanocrystal. On a quantitative basis, we were able to determine the ranges of initial reduction rates required for the formation of nanocrystals with a specific twin structure, including single-crystal, multiply twinned, and stacking fault-lined. This work represents a major step forward toward the deterministic syntheses of colloidal noble-metal nanocrystals with specific twin structures and shapes.

Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

“…Blocking of the seed surface by PAA significantly restrains silver growth at the surface, effectively increasing the ratio of the reducing agent to reacting silver35 and thus creating higher driving forces similar to what was reported in the literature for breaking symmetry during MNP regrowth2223. More details on the effect of PAA is provided in Supplementary (Supplementary Fig.…”

Shape controlled synthesis of porous tetrametallic PtAgBiCo nanoplates as highly active and methanol-tolerant electrocatalyst for oxygen reduction reaction

“…, “nanoplates” and their reduction in efficiency due to crossover of methanol from the anode to the cathode through the electrolyte membrane and the poisoning effect by carbon monoxide (CO). 6,7 After great efforts, researchers have been able to solve these challenges and found out that size controlled NPLs can be achieved in high yield using photo-induced, 4,6 seed-mediated, 8,9 “magic” reagent, 10 oxidative etching, 11,12 seed ratio 13 and reduction rate 14 techniques, as well as using the crystal symmetry of the starting nuclei. 15–17 To enhance the catalyst durability, designed catalysts should possess both good methanol tolerance and optimal activity for the oxygen reduction reaction (ORR).…”

“…16,17 Furthermore, Xia and co-workers pointed out the overall formation mechanism of NPLs by interweaving both surface chemistry and crystallographic arguments. 14 From the viewpoint of catalysis, to achieve both a high mass activity and methanol tolerance, doping Pt with a transition or main group metal might be an effective strategy, because the incorporation of the other metals into Pt-based alloys leads to a modification of the Pt electronic structure, especially transition metals (Mn, Co, Fe, and Ni) that easily transfer electrons to Pt which causes lattice contraction. Thus, the Pt–Pt distance becomes more favourable and the catalytic activity of Pt is improved.…”

Diffusion controlling porphyrin assembled structures

“…Therefore, the complex structures of materials are more dependent on kinetic factors. By changing the reaction kinetics, different structures of materials have been synthesized [6][7][8]. Our previous studies show that both chemical diffusion and reaction rates influence the structures of materials [9,10].…”