Development of Advanced Shell-Isolated Nanostructure and Their Application to In-Situ Raman Spectroscopy

Abstract

Understanding electrocatalytic mechanisms under realistic operating conditions is essential for designin efficient and selective catalysts. However, conventional electrochemical and spectroscopic techniques often struggle to capture transient intermediate and dynamic surface restructuring, particularly in harsh alkaline environments. To address these limitations, this dis ertation establishes an integrated operando platform that combines a custom-built in-situ electrochemical Raman system with chemically robust two-dimensional (2D) material–coated core–shell nanostructures. Chapter 1 outlines the fundamental background and motivation for in-situ spectroscopic analysis in alkaline electrocatalysis. Special emphasis is placed on the need for advanced probe materials capable of withstanding corrosive media while enabling precise mechanistic elu idation. Recent developments in alkaline electrocatalytic reactions such as oxygen evolution, glycerol oxidation, and nitrate reduction are introduced to highlit the necessity of monitoring potential-dependent intermediat formation. Chapter 2 describes the design and construction of a modular, fiber-coupled Raman platform with precise control over electrochemical potential. The system nables stable, high-fidelity, and time-resolved Raman measurements using diverse working electrodes, allowing in-situ characterization across a broad range of catalytic interfaces. Notably, the platform was designed to accommodate a wide range of working electrodes, enabling stable in-situ measurements regardless of electrode material or ge metry, including rod, film, and even mesh configurations. Chapter 3 presents Au@h-BN core-shell nanostructures, in which atomically thin h-BN encapsulates plasmonic Au cores. The h-BN shell provides exceptional chemical and electrochemical stability, overcoming the degradation and morphological instability commonly observed in conventional Au@SiO2 nanostructures. These nanostructures deliver strong and reproducible Raman enhancement while preserving intrinsic catalytic properties at the electrode surface. Chapter 4 applies the integrated platform to elucidate mechanistic pathways in alkaline oxygen evolution, glycerol oxidation, and nitrate reduction. I -situ electrochemical Raman spectroscopy reveals potential-dependent formation of intermediates during reaction, enabling direct identification of surface reconstruction processes, metal alloy composition and the facet-dependent reactivity trends that cannot be accessed through electrochemi al measurements alone. Overall, this work provides a structurally stable and spectroscopically powerful methodology for mechanistic investigations of alkaline electrocatalysis. The integration of 2D material encapsulation with n-situ Raman analysis establishes a generalized framework for prbing complex multielectron reactions and offers new opportunities for rational catalyst design and sustainable energy conversion technologies.