In a new JACS article (https://pubs.acs.org/doi/10.1021/jacs.9b10273) describing a collaboration between the Britt and Gray (Caltech) labs, Sayler et al. describe a set of model materials that facilitate the understanding of individual active sites in the highly active heterogeneous water oxidation catalyst, [NiFe] LDH. Heterogeneous catalysts often have a high magnetic density of active sites, complicating the interpretation of EPR spectroscopic data. This set of iron- and nickel-doped [ZnAl] LDH allow the authors to distinguish edge and bulk site and study their respective substrate binding properties. These materials offer a platform to study reactive intermediates with spectral resolution typically only observed in homogeneous catalysts.