Designing Nanoparticles and Nanoalloys with Controlled Surface and Reactivity

Abstract

Designing well-defined nanoparticles and nanoalloys is a tremendous way to achieve in-depth understanding of their intrinsic properties. In particular, structure and composition of the core and the surface of nanoalloys can be investigated by a combination of state-of-the-art in situ microscopy and spectroscopy. These nanoalloys represent a playground to establish structure-properties relationships within the nano-matter. They provide a much needed understanding of the distribution of each element within the nanoparticles, depending on the environment (gaseous atmosphere, temperature, etc.). This distribution may evolve over time. Lighter elements, such as phosphorus, are critical to the reactivity of the nanoparticle's surface in reactions such as CO or CO hydrogenation. Here, the rational design of nanoalloys will be discussed (reactants choice, composition control), in relation with their surface state. Consequences on heterogeneous and homogeneous catalytic reactions, as well as for energy storage and conversion, will be illustrated through examples.

Ensemble versus Local Restructuring of Core‐shell Nickel–Cobalt Nanoparticles upon Oxidation and Reduction Cycles

“…Core–shell nanoparticles are of interest in model studies that investigate the behavior of metals within confined domains . In this context, nickel‐cobalt bimetallic nanoparticles were selected because they are made of abundant metals and present both magnetic and catalytic properties.…”

“…Core-shell nanoparticles are of interest in model studies that investigate the behavior of metals within confined domains. [25] In this context, nickel-cobalt bimetallic nanoparticles were selected because they are made of abundant metals and present both magnetic and catalytic properties. At 350 °C and in the presence of H 2 , these nanoparticles reduce CO 2 in CO and methanol, instead of forming methane, as would be expected from a cobalt surface.…”

Bimetallic Phosphide (Ni,Cu)2P Nanoparticles by Inward Phosphorus Migration and Outward Copper Migration

“…P 2p indicated the presence of metal phosphide at 129.5 eV, 43 representing 33% of the surface phosphorus (ESI Figure S5b Ni). 36 This was expected because there is no topotactic transformation possible from Ni fcc to hexagonal Ni 2 P. 56 A fully amorphous nickel phosphide compound, showing a broad peak from 40 to 50 ° in XRD, was isolated at low temperature (90 °C). 17 In the present case, nickel is exposed at the surface of the nanoparticles and has to react first with P 4 .It would thus make sense that the first step of the reaction was the formation of a nickel phosphide amorphous shell.…”

Nanometal Thermocatalysts: Transformations, Deactivation, and Mitigation

“…As stated above, the crystallographic and chemical features, [ 50,51 ] particularly the surficial configurations, [ 52,53 ] determine the catalytic activities and functionalities of nanometals. [ 54–56 ] Undesirable configuration transformations during synthesis and catalysis undermine the structural integrity of nanometals, thereby diminishing the catalytic performance.…”