Impacts of Surface Functionalization on the Electrocatalytic Activity of Noble Metals and Nanoparticles

Zhou, Zijun; Chen, Shaowei

doi:10.5772/37594

Cited by 1 publication

(1 citation statement)

References 59 publications

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“…The enhanced ORR activity is partly ascribed to extended spilling of nanoparticle core electrons into the organic capping layers as a result of the conjugated metal–ligand bonds. The subtle diminishment of the core electronic density leads to optimal binding to oxygen intermediates and hence enhanced ORR electrocatalytic activity, as manifested by the so-called volcano plot. − This is in line with the rich manipulation of ORR activity of nanoparticle catalysts by metal–ligand (substrate) interactions, as demonstrated in numerous studies in the literature. ,− …”

Section: Impacts On Applicationsmentioning

confidence: 69%

Surface Functionalization of Metal Nanoparticles by Conjugated Metal–Ligand Interfacial Bonds: Impacts on Intraparticle Charge Transfer

Chen

Kang

et al. 2016

Acc. Chem. Res.

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Noble metal nanoparticles represent a unique class of functional nanomaterials with physical and chemical properties that deviate markedly from those of their atomic and bulk forms. In order to stabilize the nanoparticles and further manipulate the materials properties, surface functionalization with organic molecules has been utilized as a powerful tool. Among those, mercapto derivatives have been used extensively as the ligands of choice for nanoparticle surface functionalization by taking advantage of the strong affinity of thiol moieties to transition metal surfaces forming (polar) metal-thiolate linkages. Yet, the nanoparticle material properties are generally discussed within the context of the two structural components, the metal cores and the organic capping layers, whereas the impacts of the metal-sulfur interfacial bonds are largely ignored because of the lack of interesting chemistry. In recent years, it has been found that metal nanoparticles may also be functionalized by stable metal-carbon (or even -nitrogen) covalent bonds. Because of the formation of dπ-pπ interactions between the transition-metal nanoparticles and terminal carbon moieties, the interfacial resistance at the metal-ligand interface is markedly reduced, leading to the emergence of unprecedented optical and electronic properties. In this Account, we summarize recent progress in the studies of metal nanoparticles functionalized by conjugated metal-ligand interfacial bonds that include metal-carbene (M═C) and metal-acetylide (M-C≡)/metal-vinylidene (M═C═C) bonds. Such interfacial bonds are readily formed by ligand self-assembly onto nanoparticle metal cores. The resulting nanoparticles exhibit apparent intraparticle charge delocalization between the particle-bound functional moieties, leading to the emergence of optical and electronic properties that are analogous to those of their dimeric counterparts, as manifested in spectroscopic and electrochemical measurements. This is first highlighted by ferrocene-functionalized nanoparticles that exhibit nanoparticle-mediated intervalence charge transfer (IVCT) among the particle-bound ferrocenyl moieties, as manifested in electrochemical and spectroscopic measurements. Such intraparticle charge delocalization has also been observed with other functional moieties such as pyrene and anthracene, where the photoluminescence emissions are consistent with those of their dimeric derivatives. Importantly, as such electronic communication occurs via a through-bond pathway, it may be readily manipulated by the valence states of the nanoparticle cores as well as specific binding of selective molecules/ions to the organic capping shells. These fundamental insights may be exploited for diverse applications, ranging from chemical sensing to (nano)electronics and fuel cell electrochemistry. Several examples are included, such as sensitive detection of nitroaromatic derivatives, metal cations, and fluoride anions by fluorophore-functionalized metal nanoparticles, fabrication of nanoparticle-bridged molecular ...

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