Real‐Space Observation of Atomic Site‐Specific Electronic Properties of a Pt Nanoisland/Au(111) Bimetallic Surface by Tip‐Enhanced Raman Spectroscopy

Abstract

Resolving atomic site-specific electronic properties and correlated substrate-molecule interactions is challenging in real space. Now, mapping of sub-10 nm sized Pt nanoislands on a Au(111) surface was achieved by tip-enhanced Raman spectroscopy, using the distinct Raman fingerprints of adsorbed 4-chlorophenyl isocyanide molecules. A spatial resolution better than 2.5 nm allows the electronic properties of the terrace, step edge, kink, and corner sites with varying coordination environments to be resolved in real space in one Pt nanoisland. Calculations suggest that low-coordinate atomic sites have a higher d-band electronic profile and thus stronger metal-molecule interactions, leading to the observed blue-shift of Raman frequency of the N≡C bond of adsorbed molecules. An experimental and theoretical study on Pt(111) and mono- and bi-atomic layer Pt nanoislands on a Au(111) surface reveals the bimetallic effect that weakens with the increasing number of deposited Pt adlayer.

Plasmon-promoted electrocatalytic water splitting on metal–semiconductor nanocomposites: the interfacial charge transfer and the real catalytic sites

“…The N^C symmetric stretching of DMPIC located within the spectral range of 2150 to 2200 cm À1 is very sensitive to the electronic structure of the metal surface. 38 In this work, we used DMPIC as a molecular probe and compared the N^C stretching enhanced by Au NPs immobilized on the three different semiconductors: Co(OH) 2 , Ni(OH) 2 and NiCo LDH. Fig.…”

Electronic and vibrational surface-enhanced Raman scattering: from atomically defined Au(111) and (100) to roughened Au

“…[4][5][6][7][8][9] This plasmonic enhancement effect, typically referred to as Surface-Enhanced Raman Scattering (SERS), enables us to obtain chemical information not only with high detection sensitivity at the single-molecule level but also with high spatial resolution beyond the diffraction limit. [10][11][12][13][14] It is, however, known that vibrational SERS (VSERS) signals are always superimposed on a background continuum; [15][16][17] this oen limits the signal-to-noise ratio in SERS spectroscopy. The origin of the background continuum is still under discussion, although this phenomenon has been recognized as one of the major experimental anomalies since the discovery of SERS.…”

Electrochemical Scanning Probe Microscopies in Electrocatalysis

“…This so‐called “hotspot” enhances the otherwise low Raman scattering signal from molecules in close proximity to the SPM‐tip and thus allows chemical identification of molecular species on the nanoscale level . For example, TERS has been used to study the properties of bimetallic systems, such as Pt or Pd on Au(111), via probing molecules or to investigate some chemical reactions in air . However, the in situ TERS technique, electrochemical tip‐enhanced Raman spectroscopy (EC‐TERS), has been realized only recently by the Ren and Van Duyne groups, shortly followed by Domke and co‐workers .…”