Surfactant‐Assisted Stabilization of Au Colloids on Solids for Heterogeneous Catalysis

Abstract

The stabilization of surfactant-assisted synthesized colloidal noble metal nanoparticles (NPs, such as Au NPs) on solids is a promising strategy for preparing supported nanocatalysts for heterogeneous catalysis because of their uniform particle sizes, controllable shapes, and tunable compositions. However, surfactant removal to obtain clean surfaces for catalysis through traditional approaches (such as solvent extraction and thermal decomposition) can easily induce the sintering of NPs, greatly hampering their use in synthesis of novel catalysts. Such unwanted surfactants have now been utilized to stabilize NPs on solids by a simple yet efficient thermal annealing strategy. After being annealed in N flow, the surface-bound surfactants are carbonized in situ as sacrificial architectures that form a conformal coating on NPs and assist in creating an enhanced metal-support interaction between NPs and substrate, thus slowing down the Ostwald ripening process during post-oxidative calcination to remove surface covers.

Highly dispersed nickel catalysts via a facile pyrolysis generated protective carbon layer

“…The formation of carbonaceous architectures on colloidally synthesized noble metal nanoparticles has been previously reported to efficiently slow down Ostwald ripening of the metal nanoparticles. 17,18 Compared to other methods of nanoparticle synthesis such as colloidal synthesis etc. that involve multiple processing steps, use different chemicals, and are difficult to scale up, this strategy provides a simple approach to produce supported Ni nanoparticle catalysts with high dispersion by a very simple and scalable impregnation method.…”

New Strategies for the Preparation of Sinter‐Resistant Metal‐Nanoparticle‐Based Catalysts

“…Similar to the metal oxide layers, the carbon layer coated on the metal nanoparticles could also stabilize the metal nanoparticles. Zhan et al developed a general strategy to prevent the Au nanoparticle sintering during high‐temperature oxidation ( Figure ). Carbon layers are formed from pre‐coordinated dopamine carbonization on the Au surface.…”

“…g) XRD patterns of Au/TiO 2 and Au/TiO 2 ‐500 before and after long‐term reaction. Reproduced with permission 37a. Copyright 2016, American Chemical Society.…”

Catalytic Synthesis of N‐(5‐Methylfurfuryl)aniline from Bio‐Derived Carbohydrates

“…However, most of noble metal colloids are used in sol form as the effective metallic catalysts which are difficult to separate and recycle . Heterogeneous supported nano‐metallic colloid catalysts prepared through combination of nano‐metallic colloids and carriers depending on physical or chemical effects is a better choice . So activated carbon supported palladium catalyst was prepared through coating activated carbon with colloidal palladium stabilized by polyvinylpyrrolidone before carbonization.…”