Edge-sharing RuO2 single layer for stable and low overpotential acidic water electrolysis

The acidic oxygen-evolution reaction is intrinsically sluggish and requires large overpotentials, creating a key bottleneck for proton-exchange membrane water electrolysis technology. Here we show an edge-sharing single-layer oxide, 1T-phase ruthenium oxide (1T-RuO 2 ). The edge-sharing configuration enables parallel alignment of ruthenium 4 d orbitals across adjacent RuO 6 octahedral clusters, facilitating intersite electron transport, in contrast to conventional rutile-type RuO 2 with corner-/edge-sharing structures. 1T-RuO 2 exhibits high acidic oxygen-evolution reaction activity with a low overpotential of 77 mV at 10 mA cm −2 . It also delivers a mass activity of \(3,743.43\,{\rm{A}}\,{{\rm{g}}}_{\text{Ru}}^{-1}\) and a turnover frequency of 23.99 s −1 at 1.50 V versus the reversible hydrogen electrode, exceeding those of rutile-RuO 2 and showing highly competitive performance under the described experimental framework. In addition, 1T-RuO 2 maintains a current density of ∼2.9 A cm −2 at a cell voltage of 1.70 V for over 1,100 h in a proton-exchange membrane water electrolyser.