Alsuhile, Ala Abdulalem Abdo MoqbelAla Abdulalem Abdo MoqbelAlsuhilePein, PhilipPhilipPeinSchroeter, BaldurBaldurSchroeterSmirnova, IrinaIrinaSmirnovaErkey, CanCanErkey2026-03-192026-03-192026-02-19International Journal of Hydrogen Energy 219: 154030 (2026)https://hdl.handle.net/11420/62280Green hydrogen production via water electrolysis is a key technology for reaching net-zero CO₂ emission targets due to its ability to generate high-purity hydrogen with minimal environmental impact. This study investigates the effect of Co on Pt-based electrocatalysts supported on cellulose-based carbon aerogels (cellulose-CA) using supercritical deposition (SCD) on hydrogen evolution reaction (HER) activity and stability. Pt and Co precursors were deposited onto cellulose-CA via SCD and converted via two routes (ex-situ thermal and chemical) under N₂ and H₂ flow at 1 bar and 200 °C. Characterizations (ICP-MS, STEM, XPS, SEM, Raman, and XRD) confirmed successful Pt and Co incorporation and preservation of the cellulose-CA microstructure (overall accessible surface area ∼2100 – 2700 m² g⁻¹). The Co-modified electrocatalysts exhibited similar overpotentials at 20 mA/cm² despite half the Pt loading, with thermally converted Pt–Co-cellulose-CA showing the lowest overpotential (64 mV) and potential shift (4 mV). Our results demonstrate that Co-modification via SCD enhances the activity and stability of biobased CA electrocatalysts with low Pt content around 2.8 wt%.en1879-34872026Elsevierhttp://rightsstatements.org/vocab/InC/1.0/Hydrogen evolution reactionLow Pt-loading electrocatalystsCo-modificationSupercritical depositionCarbon aerogelsTechnology::600: TechnologyTechnology::660: Chemistry; Chemical Engineering::660.2: Chemical EngineeringJournal Article10.1016/j.ijhydene.2026.154030Journal Article