Insights into the Synthesis Mechanisms of Ag-Cu₃P-GaP Multicomponent Nanoparticles

Abstract

Metal−semiconductor nanoparticle heterostructures are exciting materials for photocatalytic applications. Phase and facet engineering are critical for designing highly efficient catalysts. Therefore, understanding processes occurring during the nanostructure synthesis is crucial to gain control over properties such as the surface and interface facets' orientations, morphology, and crystal structure. However, the characterization of nanostructures after the synthesis makes clarifying their formation mechanisms nontrivial and sometimes even impossible. In this study, we used an environmental transmission electron microscope with an integrated metal− organic chemical vapor deposition system to enlighten fundamental dynamic processes during the Ag-Cu 3 P-GaP nanoparticle synthesis using Ag-Cu 3 P seed particles. Our results reveal that the GaP phase nucleated at the Cu 3 P surface, and growth proceeded via a topotactic reaction involving counter-diffusion of Cu + and Ga 3+ cations. After the initial GaP growth steps, the Ag and Cu 3 P phases formed specific interfaces with the GaP growth front. GaP growth proceeded by a similar mechanism observed for the nucleation involving the diffusion of Cu atoms through/along the Ag phase toward other regions, followed by the redeposition of Cu 3 P at a specific Cu 3 P crystal facet, not in contact with the GaP phase. The Ag phase was essential for this process by acting as a medium enabling the efficient transport of Cu atoms away from and, simultaneously, Ga atoms toward the GaP-Cu 3 P interface. This study shows that enlightening fundamental processes is critical for progress in synthesizing phase-and facet-engineered multicomponent nanoparticles with tailored properties for specific applications, including catalysis.

Unveiling Step-by-Step the Bottom-Up Kinetics and Growth Mechanism of Laser-Induced Colloidal Gold Nanoparticles

“…Regarding this work’s subject, metal NPs are widely employed as optical sensors because the LSPR band is susceptible to minute changes in the refractive index near the NP surface. Thus, optical response variations can be analyzed and quantified by monitoring the shift of the LSPR band in the measured NP extinction spectrum (UV–vis–NIR region). − Metal NPs have also been used in optical spectroscopy because of the local field enhancement produced near the NP surface due to the plasmon-polariton excitation (hot spot). , Furthermore, metal NPs are applied to photothermal therapies and high-resolution displays by the color plasmonic generation and photocatalysis, to cite a few. − …”