Corrosion-resistant nanoporous high-entropy non-noble metal alloys for salinity tolerance seawater electrolysis

Given the scarcity of freshwater resources, producing hydrogen energy through the electrolysis of seawater appears to be a more economically viable and convenient solution. However, the chloride ions (Cl⁻) in seawater pose a key challenge to the durable performances of non-noble metal materials in catalyzing both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, the high-entropy non-precious metal alloys with nanoscale pore structures are developed to simultaneously achieve efficient seawater electrolysis and salinity tolerance. The Cl⁻-induced catalyst corrosion and performance degradation are effectively suppressed by graphene layers during OER process. N-doped graphene-encapsulated AlNiFeCoTi alloy (AlNiFeCoTi-NG) exhibits excellent OER performance in 1.0 M KOH with 0.5 M NaCl electrolyte, achieving an overpotential of 371 mV at a current density of 100 mA cm⁻² and durability over 165 h. In terms of HER, the incorporation of Cr into AlNiFeCoTi not only enhances the stability but also improves its activity. The high-entropy alloy catalysts are tested for overall seawater splitting, demonstrating a cell voltage of 1.84 V to reach a current density of 100 mA cm⁻². This work provides valuable insights into the development of non-noble metal catalysts for seawater electrolysis.