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 ex situ, in situ, and emerging operando 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 operando 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.