Nanoscale Chemical Analysis of Heterogeneous Catalysts Using Tip-Enhanced Raman Spectroscopy

Heterogeneous catalysts underpin much of the modern chemical industry, yet their rational design for enhanced activity, selectivity, and sustainability remains a formidable challenge due to the intrinsic structural and chemical heterogeneity of catalytic surfaces. Conventional ensemble-averaged characterization techniques often fail to capture the nanoscale complexity that governs catalytic function. Over the past two decades, tip-enhanced Raman spectroscopy (TERS) has emerged as a powerful nanoanalytical technique, offering single-molecule sensitivity and spatial resolution down to the Ångström scale. In this Review, we present TERS as a versatile, nondestructive, and label-free approach for probing heterogeneous catalytic reactions with nanometer-scale chemical specificity in air, liquid, and electrochemical environments. We first introduce the fundamental principles and instrumental implementations that underpin reliable TERS measurements. We then provide a comprehensive and critical assessment of reported <i>ex situ</i>, <i>in situ</i>, and emerging <i>operando</i> TERS studies across a wide range of catalytic systems, highlighting key mechanistic insights uniquely accessible by this technique. Finally, we discuss the technical challenges and methodological requirements for advancing <i>operando</i> TERS toward realistic reaction conditions, and outline promising directions for future research. By integrating practical considerations with conceptual advances, this Review aims to serve as a comprehensive guide for researchers seeking to apply TERS to nanoscale chemical analysis in heterogeneous catalysis.