Ligand-engineered hydrothermal synthesis of {100}-terminated ceria nanocrystals and their role as supports in OER

Facet-dependent oxide nanocrystals (NCs) are promising electrocatalyst supports due to their strong metal–support interactions, yet synthesizing facet-defined NCs with robust structures remains a challenge. We report a ligand-engineered hydrothermal strategy for synthesizing cerium oxide (CeO₂) NCs with controlled surface features, alongside counterpart CeO₂ NCs prepared through alternative methods. By tuning the type and ratio of capping ligands, two distinct morphologies, nanocubes and truncated nano-octahedra, were obtained, with facet selectivity consistent with ligand binding preferences and CeO₂ surface energy trends. When employed as supports for NiO_x catalysts prepared via alkaline precipitation, the CeO₂ NCs significantly reduced the oxygen evolution reaction overpotential, indicating strong support–catalyst interactions. Overall, this study delivers a versatile strategy for investigating facet-engineered oxide supports, advancing the rational design of oxide-supported electrocatalysts.