biostudies-literatureUnknownLin QOsmium (Os), the least expensive member of the platinum-group metals, has emerged as a promising alternative to Pt-based catalysts for the hydrogen evolution reaction (HER). However, Os-based electrocatalysts still suffer from poor stability under acidic conditions, despite recent efforts to mitigate H* over-adsorption for improved intrinsic activity. Here, we design a porous CeO₂ support that enables the atomic dispersion of Os, forming an Os single-atom catalyst (Os_SA-CeO₂). Unlike traditional flat-film supports, the porous CeO₂ architecture prevents Os aggregation and achieves 100% interfacial anchoring of Os atoms. The resulting strong electronic coupling enables tight anchoring of Os and activates the CeO₂ matrix with abundant oxyChemical sciencehttps://www.ebi.ac.uk/biostudies/studies/S-EPMC12908458biostudies-literatureAtomic-level interface engineering enables efficient and durable acidic hydrogen evolution of osmium at large current densities.PMC12908458Li HLin QLiang WHong YZhang LYu JLiao MSong ZfalseAtomic-level interface engineering enables efficient and durable acidic hydrogen evolution of osmium at large current densities.Osmium (Os), the least expensive member of the platinum-group metals, has emerged as a promising alternative to Pt-based catalysts for the hydrogen evolution reaction (HER). However, Os-based electrocatalysts still suffer from poor stability under acidic conditions, despite recent efforts to mitigate H* over-adsorption for improved intrinsic activity. Here, we design a porous CeO₂ support that enables the atomic dispersion of Os, forming an Os single-atom catalyst (Os_SA-CeO₂). Unlike traditional flat-film supports, the porous CeO₂ architecture prevents Os aggregation and achieves 100% interfacial anchoring of Os atoms. The resulting strong electronic coupling enables tight anchoring of Os and activates the CeO₂ matrix with abundant oxy2026-01-01T00:00:00Z2026 Feb2026-07-16T05:01:44.799Z2026-07-09T13:10:29.942ZS-EPMC129084584170503910.1039/d5sc09741j