Fig. 2.

Overview of atom probe tomography results for fresh and aged Cu-ZSM-5. a Reconstructed needle of fresh Cu-ZSM-5 (1, full results are in Supplementary Fig. 22) with Cu (red) and Al (blue) ions shown and 1.8% Cu isoconcentration surfaces shown, this is also provided as Supplementary Movie 1. Bonding box dimensions are 40 × 43 × 140 nm³. b Radial distribution functions (RDFs) in fresh Cu-ZSM-5 for Al and Cu centers. Strong Cu–Cu affinity is indicated, as well as much weaker, but still significant affinities between all other species. An Al–Cu affinity is expected due to Cu exchanging onto paired Al sites, as indicated in the schematic. c Normalized compositional histogram across the 1.8% Cu isoconcentration surfaces in fresh Cu-ZSM-5, with the structures of potential CuO species shown. d RDFs in aged Cu-ZSM-5 (3, full results are in Supplementary Fig. 26) for Al and Cu centers, with the structure of a potential CuO species shown. Strong affinities are indicated between all species, pointing to the formation of copper aluminate domains after aging due to Cu–Al aggregation. e Al/Cu ratio across the 8% Al isoconcentration surfaces in aged Cu-ZSM-5, the stoichiometry of Al/Cu = 2 is consistent with CuAl₂O₄ spinel, and the O/Cu and O/Al values are also stoichiometric, see Supplementary Fig. 27. f Reconstructed needle of aged Cu-ZSM-5 (3) with 5% Cu and 8% Al isoconcentration surfaces shown, this is also included as Supplementary Movie 3. Bonding box dimensions are 15 × 15 × 43 nm³. All error bars were calculated from counting statistics using the method described in ref. ⁵⁵