Solving the structure of “single-atom” catalysts using machine learning – assisted XANES analysis

Abstract

“Single-atom” catalysts (SACs) have demonstrated excellent activity and selectivity in challenging chemical transformations such as photocatalytic CO2 reduction. For heterogeneous photocatalytic SAC systems, it is essential to obtain sufficient information...

Design of Single-Atom Catalysts and Tracking Their Fate Using Operando and Advanced X-ray Spectroscopic Tools

“…Frenkel, Li, and co-workers demonstrated machine learning assisted modeling of XAS spectra of SACs that is able to be used for both qualitative and quantitative analyses of isolated metal structures. 433 In their work as shown in Figure 67, Co SACs were synthesized by grafting molecular Co complex over C 3 N 4 semiconductor for the photocatalytic reduction of CO 2 . The authors followed the XANES spectra at the Co K-edge under reaction conditions with different ML approaches, including principle component analysis (PCA), linear combination analysis (LCF), K-means clustering, and neural network (NN).…”

“…Frenkel, Li, and co-workers demonstrated machine learning assisted modeling of XAS spectra of SACs that is able to be used for both qualitative and quantitative analyses of isolated metal structures . In their work as shown in Figure , Co SACs were synthesized by grafting molecular Co complex over C 3 N 4 semiconductor for the photocatalytic reduction of CO 2 .…”

“…(a) XANES spectra at Cu K-edge during photocatalytic reduction of CO 2 , (b) comparisons of experimental (black) and all theoretical XANES spectra with two descriptor changing (d C and d O ), and (c) scheme of application of NN-XANES to SACs system of Co-cyclam-CO. Adapted with permission from ref . Copyright Royal Society of Chemistry.…”

Machine learning for design principles for single atom catalysts towards electrochemical reactions

“…[152][153][154][155] ML can also be used for the interpretation of characterization of SACs. 156,157 For example, as shown in Fig. 4, ML techniques have been used to interpret the EXAFS spectra based on which edge sites (zigzag or armchair) are responsible for the HER activity of a cobalt SAC embedded in graphene.…”

X-ray Absorption Spectroscopy Studies of a Molecular CO2-Reduction Catalyst Deposited on Graphitic Carbon Nitride

“…To obtain atomic-level structural information, we previously employed X-ray absorption spectroscopy (XAS) to characterize transition metal catalysts in both ex-situ and in-situ/operando studies. ,− Specifically, the extended X-ray absorption fine structure (EXAFS) analysis can provide valuable insights into the local geometric structure and coordination environment of the metal sites. − The X-ray absorption near edge structure (XANES) spectra are particularly sensitive to the electronic structure of the metal center and its local environment. − Our recent work utilized XANES spectra of CoX/C 3 N 4 to probe possible intermediates during photocatalytic CO 2 reduction. While the chemometrics-based approach for separating between different Co structures coexisting in reaction conditions was successful, the choice of the structural model for using a machine learning – based method of XANES data analysis was guided by human expertise only.…”