Single-atom catalysts (SACs) have attracted widespread attention in the field of catalysis due to their unique atomic dispersion characteristics, extremely high atomic utilization efficiency, and excellent catalytic performance. Accurately identifying their microscopic chemical environment is of crucial importance for revealing the catalytic mechanism and promoting the innovative design of high-performance catalysts, especially the developing of machine learning (ML) driven precision chemistry. X-ray absorption fine structure (XAFS) technology has become the core means in SACs research because of its high sensitivity to specific elements, the ability to simultaneously detect electronic and geometric structures, and good sample compatibility. This review begins with the fundamental principles of XAFS technology, systematically elucidating its key applications and significant advantages in the characterization of metal sites in SACs and in situ detecting of catalytic reactions. Furthermore, from the perspective of integrating theoretical calculations with experimental studies, it delves into the importance of using XAFS in conjunction with first-principles calculations and other methods to accurately determine the fine structure of active sites. Finally, this review delivers an in-depth discussion of the key challenges inherent in XAFS characterization and presents a forward-looking perspective on its future development. This work aims to furnish a robust theoretical framework and practical guidelines to foster a profound understanding of the intrinsic relationship between the structural characteristics and performance of SACs, thereby facilitating the targeted design of SACs.

Simultaneous conversion of CO₂ and biomass into value-added chemicals through solar-driven catalysis holds tremendous importance for fostering a sustainable circular economy. Herein, plasmonic Bi quantum dots were immobilized on phosphoric acid modified attapulgite (P-ATP) nanorod using an in-situ reduction–deposition method, and were employed for photocatalytic reduction of CO₂ coupled with oxidation of biomass-derived benzyl alcohol. Results revealed that Bi atoms successfully integrated into the basal structure of P-ATP, forming chemically coordinated Bi–O–Si bonds that served as efficient transportation channels for electrons. The incorporation of high-density monodispersed Bi quantum dots induced a surface plasmon resonance (SPR) effect, expanding the light absorption range into the near-infrared region. As a consequence, the photo-thermal transformation was significantly accelerated, leading to enhanced reaction kinetics. Notably, 50% Bi/P-ATP nanocomposite exhibited the highest plasmon-mediated photocatalytic CH₄ generation (115.7 μmol·g⁻¹·h⁻¹) and CO generation (44.9 μmol·g⁻¹·h⁻¹), along with remarkable benzaldehyde generation rate of 79.5 μmol·g⁻¹·h⁻¹ in the photo-redox coupling system under solar light irradiation. The hydrogen protons released from the oxidation of benzyl alcohol facilitated the incorporation of more hydrogen protons into CO₂ to form key CH₃O⁻ intermediates. This work demonstrates the synergistic solar-driven valorization of CO₂ and biomass using natural mineral based catalyst.