Unraveling the Chirality Transfer from Circularly Polarized Light to Single Plasmonic Nanoparticles.

Due to their broken symmetry, chiral plasmonic nanostructures have unique optical properties and numerous applications. However, there is still a lack of comprehension regarding how chirality transfer occurs between circularly polarized light (CPL) and these structures. Here, we thoroughly investigate the plasmon-assisted growth of chiral nanoparticles from achiral Au nanocubes (AuNCs) via CPL without the involvement of any chiral molecule stimulators. We identify the structural chirality of our synthesized chiral plasmonic nanostructures using circular differential scattering (CDS) spectroscopy, which is correlated with scanning electron microscopy imaging at both the single-particle and ensemble levels. Theoretical simulations, including hot-electron surface maps, reveal that the plasmon-induced chirality transfer is mediated by the asymmetric distribution of hot electrons on achiral AuNCs under CPL excitation. Furthermore, we shed light on how this plasmon-induced chirality transfer can also be utilized for chiral growth in bimetallic systems, such as Ag or Pd on AuNCs. The results presented here uncover fundamental aspects of chiral light-matter interaction and have implications for the future design and optimization of chiral sensors and chiral catalysis, among others.

Surface-Enhanced Raman Spectroscopic Evidence of Key Intermediate Species and Role of NiFe Dual-Catalytic Center in Water Oxidation.

NiFe-based electrocatalysts have attracted great interests due to the low price and high activity in oxygen evolution reaction (OER). However, the complex reaction mechanism of NiFe-catalyzed OER has not been fully explored yet. Detection of intermediate species can bridge the gap between OER performances and catalyst component/structure properties. Here, we performed label-free surface-enhanced Raman spectroscopic (SERS) monitoring of interfacial OER process on Ni3 FeOx nanoparticles (NPs) in alkaline medium. By using bifunctional Au@Ni3 FeOx core-satellite superstructures as Raman signal enhancer, we found direct spectroscopic evidence of intermediate O-O- species. According to the SERS results, Fe atoms are the catalytic sites for the initial OH- to O-O- oxidation. The O-O- species adsorbed across neighboring Fe and Ni sites experiences further oxidation caused by electron transfer to NiIII and eventually forms O2 product.

Synthesis of a Gold-Metal Oxide Core-Satellite Nanostructure for In†Situ SERS Study of CuO-Catalyzed Photooxidation.

This work reports on an assembling-calcining method for preparing gold-metal oxide core-satellite nanostructures, which enable surface-enhanced Raman spectroscopic detection of chemical reactions on metal oxide nanoparticles. By using the nanostructure, we study the photooxidation of Si-H catalyzed by CuO nanoparticles. As evidenced by the in situ spectroscopic results, oxygen vacancies of CuO are found to be very active sites for oxygen activation, and hydroxide radicals (*OH) adsorbed at the catalytic sites are likely to be the reactive intermediates that trigger the conversion from silanes into the corresponding silanols. According to our finding, oxygen vacancy-rich CuO catalysts are confirmed to be of both high activity and selectivity in photooxidation of various silanes.

Light inhibition of hydrogenation reactions on Au-Pd nanocoronals as plasmonic switcher in catalysis.

Light, as a powerful energy source, has motivated the many endeavors of chemists in photochemical transformations. We were delighted to find that light has an inhibition effect on hydrogenation reactions. Exploring this previously unperceived effect will bring renewed understanding of interactions of light and matter. This work provides a breakthrough in ways to remotely control chemical reactions by light.

In situ surface-enhanced Raman spectroelectrochemistry reveals the molecular conformation of electrolyte additives in Li-ion batteries.

We report the mechanism of rhodamine B (RhB) acting as an electrolyte additive in Li/graphite cells. We show that the cycle performance and rate capability of graphite are enhanced in carbonate-based electrolytes containing 0.2 wt% RhB. By using silica-encapsulated Au nanoparticles, in situ surface-enhanced Raman spectroscopy (SERS) is applied to study the graphite/electrolyte interface. We find that the adsorption orientation of RhB molecules on the surface of graphite can be modulated by the applied potential: vertical adsorption at higher potentials while horizontal adsorption takes place at lower potentials. This behavior effectively suppresses the electrolyte solvent decomposition, as well as electrode corrosion while improving the Li+ diffusion. This work shows that SERS is a powerful tool for interfacial analysis of battery systems and provides new ideas for rational design of electrolyte additives.