Decoding the electronic and structural fingerprints of single-atom catalysts via DFT-assisted XANES analysis

Single-atom catalysts (SACs), composed of isolated metal atoms dispersed on solid supports, represent the ultimate expression of atomic efficiency in catalysis. Their remarkable activity and selectivity arise from local coordination environments and adjustable oxidation states, yet precise determination of these features remains an enduring challenge. Among modern characterization techniques, X-ray absorption near-edge structure (XANES) spectroscopy stands out for its sensitivity to both electronic and geometric structure, though its interpretation is often constrained by empirical comparison with bulk references. Here we introduce a density functional theory-based computational spectroscopy framework for the quantitative interpretation of Cu K-edge XANES spectra. The approach accurately reproduces experimental edge positions and fine-structure features across benchmark copper systems, including metallic Cu, Cu₂O, CuO, and CuSO₄·5H₂O. We then employ this framework to reveal the oxidation state, coordination geometry, and hydration environment of Cu single atoms supported on cyanographene and N-doped graphene, demonstrating direct correspondence between spectral signatures and atomic-scale structure. This methodology establishes a robust and transferable route for connecting XANES features with the underlying electronic and structural characteristics of SACs, thereby advancing the rational design of atomically precise catalysts.