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Probing Single-Particle Electrocatalytic Activity at Facet-Controlled Gold Nanocrystals.

ABSTRACT: Electrocatalytic reduction reactions (i.e., the hydrogen evolution reaction (HER) and oxygen reduction reaction) at individual, faceted Au nanocubes (NCs) and nano-octahedra (ODs) expressing predominantly {100} and {111} crystal planes on the surface, respectively, were studied by nanoscale voltammetric mapping. Cyclic voltammograms were collected at individual nanoparticles (NPs) with scanning electrochemical cell microscopy (SECCM) and correlated with particle morphology imaged by electron microscopy. Nanoscale measurements from a statistically informative set of individual NPs revealed that Au NCs have superior HER electrocatalytic activity compared to that of Au ODs, in good agreement with macroscale cyclic voltammetry measurements. Au NCs exhibited more particle-to-particle variation in catalytic activity compared to that with Au ODs. The approach of single-particle SECCM imaging coupled with macroscale CV on well-defined NPs provides a powerful toolset for the design and activity assessment of nanoscale electrocatalysts.

SUBMITTER: Choi M

PROVIDER: S-EPMC7727918 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Probing Single-Particle Electrocatalytic Activity at Facet-Controlled Gold Nanocrystals.

Choi Myunghoon M Siepser Natasha P NP Jeong Soojin S Wang Yi Y Jagdale Gargi G Ye Xingchen X Baker Lane A LA

Nano letters 20200121 2

Electrocatalytic reduction reactions (i.e., the hydrogen evolution reaction (HER) and oxygen reduction reaction) at individual, faceted Au nanocubes (NCs) and nano-octahedra (ODs) expressing predominantly {100} and {111} crystal planes on the surface, respectively, were studied by nanoscale voltammetric mapping. Cyclic voltammograms were collected at individual nanoparticles (NPs) with scanning electrochemical cell microscopy (SECCM) and correlated with particle morphology imaged by electron mic ...[more]

PMID: 31917592

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Project description:The facet-dependent redox reactions of diruthenium metal-string complexes by gold nanoparticles (AuNPs) are explored by using the surface-enhanced Raman scattering (SERS) technique. Gold nano-rhombic dodecahedrons (AuRDs), gold nanocubes (AuNCs), and gold octahedrons (AuOhs) with exclusive facets {110}, {100}, and {111}, respectively, were synthesized. These AuNPs linked face-to-face by metal-string complexes Ru2M(dpa)4Cl2 (dpa = dipyridyl amino, M = Ni, Cu) with chloride axial ligands serve as both SERS substrates and reducing agents in the reactions. We employ the diruthenium core in these complexes with multiple redox states to study the reduction ability of varied AuNP facets upon plasmonic excitation. In Ru2Ni(dpa)4Cl2, the Ru-Ru stretching mode νRu-Ru str. lies at 327 cm-1 on the SERS substrate AuOh, but this band shifts to 313 cm-1 on the AuRD and AuNC. The diruthenium moiety was reduced to [Ru2]4+ by the AuRD facet {110} and the AuNC {100}. The gold nanorods in the solution prepared with metal-string complexes bridging head-to-head on {111} facets were used for the SERS substrate. The SERS curves of the complexes in these self-assembled head-to-head rods display νRu-Ru str. at 327 cm-1, which is assigned to having an [Ru2]5+ core. Hence, facets {110} and {100} have a reduction reactivity greater than that of {111}. In Ru2Cu(dpa)4Cl2, the νRu-Ru str. is observed to lie at 312 cm-1 on AuRD, but shifts to 320 cm-1 on the AuNC and AuOh. In the latter cases, the diruthenium moiety was reduced to having a charge of 4+ with electronic configuration π*2δ*2, whereas the former case band at 312 cm-1 with a weaker Ru-Ru bonding is also attributed to [Ru2]4+ but with electron configuration π*4. π*4 lies at an energy greater than π*2δ*2. The electrochemical SERS spectra of diruthenium complexes were recorded to verify their oxidation states. Conclusively, these results yield the reduction reactivity of the following facet: {110} > {100} > {111}. According to the results of the redox reactions, the valence states of the diruthenium metal-string complexes are verified. In the [Ru2] n+ core, n = 4 π*4, 4 π*2δ*2, 5 π*2δ*, and 6 π*δ*, and the νRu-Ru str. is 312, 320, 327, and 337 cm-1, respectively.

Dataset Information

Probing Single-Particle Electrocatalytic Activity at Facet-Controlled Gold Nanocrystals.

Publications

Probing Single-Particle Electrocatalytic Activity at Facet-Controlled Gold Nanocrystals.

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