Facet-Dependent Selectivity and Performance of PdSe₂ Microstructure Electrocatalysts for Two-Electron Oxygen Reduction Reaction

Electrifying hydrogen peroxide production via the 2-electron oxygen reduction reaction (2e- ORR) has emerged as a promising alternative to the hazardous centralized anthraquinone process that is the current standard for industrial production. Our group recently identified the van der Waals layered material PdSe₂ as a selective, active, and stable 2e- ORR electrocatalyst in neutral and acidic solutions. DFT calculations suggest that the selectivity of the ORR reaction depends on the facets of this layered material, however, hydrothermally-grown PdSe₂ samples exhibit small aspect-ratios and large variations in the surface facets. Through chemical vapor deposition synthesis of PdSe₂, we were able to select towards preferential exposure of the basal plane facets, and directly nucleate and grow the PdSe₂ catalyst on electrode surfaces. Electrochemical and structural characterization of the different PdSe₂ morphologies are being carried out through a multimodal approach, including rotating ring disk electrode (RRDE), operando soft and hard x-ray absorption studies, and scanning electrochemical microscopy (SECM), towards the goal of revealing the facet-dependent selectivity and performance of PdSe₂. We hope our results will further elucidate the catalytic mechanism(s) of this new 2e- ORR electrocatalyst, and enable general approaches that can be applied to the structure-property and mechanistic studies of other nanostructured electrocatalysts.