In situ electrochemical surface-enhanced Raman spectroscopy study of CO electrooxidation on PtFe nanocatalysts

Spinous Au@Ag Bimetallic Nanowires: Synthesis and In Situ Monitoring SERS of Plasmonic Catalysis

In situ monitoring of reactant transformations at metal catalyst surfaces and/or interfaces, combined with the identification of intermediate species and products, is vital for elucidating catalytic processes and behaviors. We developed innovative spinous Au@Ag nanowires (NWs) with a bimetallic structure and dense alloy protrusions, demonstrating both catalytic activity and surface-enhanced Raman spectroscopy (SERS) capabilities, thereby facilitating in situ SERS tracking of reactions. The spinous Au@Ag NWs exhibit sharp spikes on their surface, providing a large number of catalytically active sites. They demonstrate outstanding sensitivity, signal reproducibility, and homogeneity when detecting representative dye molecules like crystal violet. Furthermore, the spinous Au@Ag NWs exhibit outstanding catalytic performance, enhancing the separation and movement of photogenerated electron-hole pairs. This research offers important insights for the design of multifunctional SERS substrates and paves the way for new opportunities in the in situ monitoring of catalytic processes.

Recent Approaches for Cleaving the C─C Bond During Ethanol Electro-Oxidation Reaction

Direct ethanol fuel cells (DEFCs) play an indispensable role in the cyclic utilization of carbon resources due to its high volumetric energy density, high efficiency, and environmental benign character. However, owing to the chemically stable carbon-carbon (C─C) bond of ethanol, its incomplete electrooxidation at the anode severely inhibits the energy and power density output of DEFCs. The efficiency of C─C bond cleaving on the state-of-the-art Pt or Pd catalysts is reported as low as 7.5%. Recently, tremendous efforts are devoted to this field, and some effective strategies are put forward to facilitate the cleavage of the C─C bond. It is the right time to summarize the major breakthroughs in ethanol electrooxidation reaction. In this review, some optimization strategies including constructing core-shell nanostructure with alloying effect, doping other metal atoms in Pt and Pd catalysts, engineering composite catalyst with interface synergism, introducing cascade catalytic sites, and so on, are systematically summarized. In addition, the catalytic mechanism as well as the correlations between the catalyst structure and catalytic efficiency are further discussed. Finally, the prevailing limitations and feasible improvement directions for ethanol electrooxidation are proposed.

Shell isolated nanoparticle enhanced Raman spectroscopy for mechanistic investigation of electrochemical reactions

Electrochemical conversion of abundant resources, such as carbon dioxide, water, nitrogen, and nitrate, is a remarkable strategy for replacing fossil fuel-based processes and achieving a sustainable energy future. Designing an efficient and selective electrocatalysis system for electrochemical conversion reactions remains a challenge due to a lack of understanding of the reaction mechanism. Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is a promising strategy for experimentally unraveling a reaction pathway and rate-limiting step by detecting intermediate species and catalytically active sites that occur during the reaction regardless of substrate. In this review, we introduce the SHINERS principle and its historical developments. Furthermore, we discuss recent SHINERS applications and developments for investigating intermediate species involved in a variety of electrocatalytic reactions.

Recent advances in plasmon-enhanced Raman spectroscopy for catalytic reactions on bifunctional metallic nanostructures

Metallic nanostructures exhibit superior catalytic performance for diverse chemical reactions and the in-depth understanding of reaction mechanisms requires versatile characterization methods. Plasmon-enhanced Raman spectroscopy (PERS), including surface-enhanced Raman spectroscopy (SERS), shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), and tip-enhanced Raman spectroscopy (TERS), appears as a powerful technique to characterize the Raman fingerprint information of surface species with high chemical sensitivity and spatial resolution. To expand the range of catalytic reactions studied by PERS, catalytically active metals are integrated with plasmonic metals to produce bifunctional metallic nanostructures. In this minireview, we discuss the recent advances in PERS techniques to probe the chemical reactions catalysed by bifunctional metallic nanostructures. First, we introduce different architectures of these dual-functionality nanostructures. We then highlight the recent works using PERS to investigate important catalytic reactions as well as the electronic and catalytic properties of these nanostructures. Finally, we provide some perspectives for future PERS studies in this field.

In Situ Surface-Enhanced Raman Spectroscopy Characterization of Electrocatalysis with Different Nanostructures

As energy demands increase, electrocatalysis serves as a vital tool in energy conversion. Elucidating electrocatalytic mechanisms using in situ spectroscopic characterization techniques can provide experimental guidance for preparing high-efficiency electrocatalysts. Surface-enhanced Raman spectroscopy (SERS) can provide rich spectral information for ultratrace surface species and is extremely well suited to studying their activity. To improve the material and morphological universalities, researchers have employed different kinds of nanostructures that have played important roles in the development of SERS technologies. Different strategies, such as so-called borrowing enhancement from shell-isolated modes and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS)-satellite structures, have been proposed to obtain highly effective Raman enhancement, and these methods make it possible to apply SERS to various electrocatalytic systems. Here, we discuss the development of SERS technology, focusing on its applications in different electrocatalytic reactions (such as oxygen reduction reactions) and at different nanostructure surfaces, and give a brief outlook on its development.

Water oxidation intermediates on iridium oxide electrodes probed by in situ electrochemical SHINERS

Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is applied to the study of a state-of-the-art water oxidation electrocatalyst, IrO_x, during oxygen evolution.

In Situ Analysis of Surface Catalytic Reactions Using Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy

Electrochemistry and heterogeneous catalysis continue to attract enormous interest. In situ surface analysis is a dynamic research field capable of elucidating the catalytic mechanisms of reaction processes. Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is a nondestructive technique that has been cumulatively used to probe and analyze catalytic-reaction processes, providing important spectral evidence about reaction intermediates produced on catalyst surfaces. In this perspective, we review recent electrochemical- and heterogeneous-catalysis studies using SHINERS, highlight its advantages, summarize the flaws and prospects for improving the SHINERS technique, and give insight into its future research directions.