RESEARCH / A0044
Nanoconfined single-atom catalysis enables long-lived hydroxyl radicals for low-cost, versatile on-site water purification
Read the original paper · 10.1016/j.oneear.2026.101778 ↗
Source figures may contain other techniques and soft X-ray spectra. C, N and O measurements are outside our current hard-XAFS testing range.
Figure 2. Design strategy and structural characterizations of Fe1-ZSM-5 (A) Schematic illustration of constructing confined Fe single atoms in ZSM-5 microporous channels and scalable production. (B) FTIR spectra of hydroxyl groups within zeolite channels. (C) TG-MS analysis of ferrocene thermal decomposition during the heating process. (D) Comparison of pore volume and width before and after loading Fe atoms. (E) Aberration-corrected HAADF-STEM (AC-HAADF-STEM) images. Scale bars, 5 nm in the left image and 2 nm in the right image. (F) Valence state of Fe1-ZSM-5 along with relevant reference (i.e., Fe foil, FeO, Fe2O3, and K2FeO4). (G) Coordination structure of Fe atoms determined from the Fe K-edge Fourier-transformed EXAFS spectra (lines) and fits (spheres).
Figure 4. Identification of adsorbed ⋅OH and its relationship with atomic dispersion (A) Fluorescence images of chemiluminescence probe trapped ⋅OH. (B) EPR spectra of DMPO- ⋅OH adduct signal with or without adsorbed ⋅OH scavengers. (C) Quantitative determination of free and adsorbed ⋅OH. (D) Fe K-edge FT-EXAFS of Fe1-ZSM-5 synthesized under different sweeping durations of gas ferrocene. (E) Adsorbed ⋅OH proportion of variously dispersed Fe atoms and its relationship with 4-CP degradation rate. (F) Relative dispersion score of Fe as a function of sweeping time. The inset represents elemental Fe distribution maps. Reaction conditions unless otherwise noted: [catalyst] = 2 g L−1, [H2O2]0 = 5 mM, [4-CP]0 = 0.1 mM, [NaF] = [F−] = 10 mM, pH=7, temperature = 25◦C. Error bars in (C) and (E) represent the standard deviation of three independent experiments. Scale bars, 100 μm in (A) and 200 nm in (F).
Figure 5. Mechanistic insights via operando spectroscopy and theoretical calculation of confined Fe atoms (A) Schematic diagram of in situ XAFS. (B and C) Normalized Fe K-edge XANES and FT-EXAFS spectra during different H2O2 activation stages. (D and E) Corresponding evolutions of coordination environment (D) and valence state (E) of confined iron sites. The line denotes the sample, and the spherical marker denotes the fit. (F–H) Theoretical investigation: the adsorption energy and Bader charge calculation of ⋅OH at the confined iron sites (F), ⋅OH orbital hybridization with iron during the adsorption process (G), and comparison of the H2O2 activation process in confined Fenton-like and homogeneous Fenton systems (H).