Stabilizing Electron‐Deficient Ru Nanoclusters via Strong Electronic Metal‐Support Interaction for Practical Anion‐Exchange Membrane Electrolyzer

Abstract Ruthenium (Ru)‐based hydrogen evolution reaction (HER) electrocatalysts are promising candidates for assembling high‐performance anion exchange membrane water electrolyzer (AEMWE) while their intrinsic activities are restricted due to the strong Ru─H bond strength. Herein, we present the synthesis and stabilization of electron‐deficient Ru nanoclusters on oxygen‐functionalized carbon nanotube (Ru/O‐CNT) via strong electronic metal‐support interaction (EMSI) toward highly efficient and stable alkaline HER. A scalable high‐temperature shock method is used to anchor Ru nanoclusters on O‐CNT, which suppresses the aggregation of Ru clusters and the loss of O anion during synthesis, thus strengthening the EMSI between the two components via Ru–O–C link. The strong EMSI helps to stabilize Ru at electron‐deficient state at reductive potentials and optimizes the Ru─H bond strength. Consequently, Ru/O‐CNT delivers outstanding performances for alkaline HER with a small overpotential of 10 mV at 10 mA cm⁻², which is superior to the benchmark Pt/C and most reported Ru‐based electrocatalysts. More impressively, an AEMWE assembled with Ru/O‐CNT as cathode achieves high current densities of 1 and 5 A cm⁻² at low cell voltages of 1.68 and 2.09 V, respectively, at a Ru mass loading of only 20 µg cm⁻².