Coupling RuO₂ nanofibers with ionic crystal significantly enhances the water electrolysis performance

Ruthenium (Ru) has emerged as a highly promising and cost-effective alternative to Ir- and Pt-based electrocatalysts for water electrolysis, making the development of efficient and stable Ru-based bifunctional catalysts a critical research objective. Herein, an AgCl/RuO₂ heterojunction is prepared via a facile electrospinning-calcination strategy. The AgCl undergoes a reduction to form metallic Ag under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes, which can be integrated with RuO₂ active sites to facilitate H₂O dissociation and enhance the electron transfer while simultaneously suppressing RuO₂ over-oxidation. Therefore, the optimized AgCl/RuO₂-300 NFs demonstrate exceptional HER performance, achieving an overpotential of only 105 mV at 1000 mA cm^-2 in 1 M KOH, along with remarkable stability, maintaining continuous operation for 270 h at this high current density. Furthermore, this catalyst also displays favorable alkaline OER performance, requiring overpotentials of just 214 and 275 mV to reach 10 and 100 mA cm^-2, respectively. Crucially, an electrolyzer assembled with this bifunctional catalyst achieves 10 mA cm^-2 at a low cell voltage of 1.49 V, outperforming commercial Pt/C||RuO₂ system and most recently reported electrolyzers. Additionally, the AgCl/RuO₂-300 NFs show significant potential for seawater electrolysis, demonstrating exceptional corrosion resistance and robust stability. This work offers a novel strategy for designing highly active and durable Ru-based electrocatalysts for both alkaline freshwater and seawater electrolysis.