Observation of a robust and highly active catalyst for water electrolysis under the current density of 1000 mA cm-2

Abstract

Despite the fruitful achievements in the development of hydrogen production catalysts with record-breaking performances, there is still a lack of durable catalysts that could work under large current densities (> 1000 mA cm− 2). In the context of this need, we investigated the catalytic behaviors of Sr2RuO4 (SRO) bulk single crystals with well-defined surface crystal structures, which is a benchmark material to explore exotic metallic states and electronic structures. This single crystal has demonstrated remarkable activities under the current density of 1000 mA cm− 2, which require overpotentials of 182 and 278 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively, after ohmic correction. These values slightly increased to 272 and 354 mV even without iR correction, exhibiting high potential for industrial-scale hydrogen production. The high performance is also evidenced by the 56 days of continuous testing at a high current density of above 1000 mA cm− 2 and then under operating temperatures of 70 ℃ for alkaline electrolysis. The in-situ formation of ferromagnetic Ru clusters at the crystal surface is critical for the outstanding catalytic activity, endowing the single-crystal catalyst with low charge transfer resistance and high wettability for rapid gas bubble removal. Density functional theory calculations indicate that SRO gains electrons from the Ru clusters, thus leading to the thermodynamically favorable hydrogen desorption for the rapidly modified catalysts. More generally, our experiment exemplifies the potential of designing novel HER catalysts that work under industrial-scale current density.