Durable Hierarchical Porous PtCo Nanoparticle Films for Hydrogen Evolution Reaction in Simulated Seawater

Highly active Pt-based seawater hydrogen evolution catalysts have been extensively developed amid global freshwater and energy shortages. However, high costs and limited durability remain critical challenges that need to be addressed. In this work, hierarchical porous Pt₆₀Co₄₀ and Pt₁₅Co₈₅ nanoparticle films were fabricated via electrodeposition, utilizing nonionic surfactant F127 as a mesoporous template. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses revealed that both PtCo nanoparticle films are single-phase nanocrystalline, corresponding to Pt₃Co (40 atom % Co) and PtCo (85 atom % Co) phases, respectively. In alkaline simulated seawater (1 M KOH + 3.5 wt % NaCl), both Pt₆₀Co₄₀ and Pt₁₅Co₈₅ demonstrate exceptional HER activity, achieving low overpotentials of 48 and 45 mV, respectively, at a current density of −10 mA cm^–2. Moreover, Pt₆₀Co₄₀ exhibits considerable durability, maintaining a low overpotential of 61 mV after 120 h of long-term continuous electrolysis. This study provides valuable insights into the design and fabrication of seawater hydrogen evolution catalysts with robust HER activity and durability, particularly highlighting the importance of composition and morphology optimization for noble metal-based catalysts.