Single-Atom Photocatalysts on TiO2 : Insights from X-ray Absorption Spectroscopy

TL;DR

This paper reviews how X-ray absorption spectroscopy (XAS) is used to analyze single-atom catalysts on TiO2, revealing atomic structure, electronic states, and reaction mechanisms to improve photocatalytic performance.

Contribution

It provides a comprehensive overview of XAS applications in characterizing TiO2-supported SACs, including in situ analysis and element-specific insights, advancing understanding of photocatalyst behavior.

Findings

XAS effectively probes atomic structure and electronic states of SACs.

In situ XAS monitors real-time changes during photocatalytic reactions.

Element-specific analysis enhances understanding of bimetallic SACs.

Abstract

Surface modification of TiO2 with single-atom catalysts (SACs) is an effective strategy for enhancing photocatalytic efficiency. However, thorough characterization of SACs at the atomic scale remains challenging. X-ray absorption spectroscopy (XAS) offers unique advantages for the in-depth analysis of TiO2-supported SACs. By employing XAS, the local atomic structure, oxidation state, and electronic properties of the SACs, as well as the underlying photocatalytic mechanism, can be revealed. Herein, we present a short review on the application of XAS in studying TiO2-supported SACs. We first elucidate the key role of XAS in simultaneously probing the structure and electronic properties of monometallic SACs across different periods. Next, we discuss XAS studies of bimetallic SACs from the perspective of each constituent element and highlight the element-specific capabilities of XAS for analyzing multi-element SACs. Finally, we demonstrate how in situ XAS can effectively monitor structural and electronic property changes in SACs under real photocatalytic reaction conditions. Additionally, we provide practical suggestions for utilizing XAS more efficiently in the analysis of various SAC systems.