Synergistic Mechanism of Sub‐Nanometric Ru Clusters Anchored on Tungsten Oxide Nanowires for High‐Efficient Bifunctional Hydrogen Electrocatalysis

Abstract The construction of strong interactions and synergistic effects between small metal clusters and supports offers a great opportunity to achieve high‐performance and cost‐effective heterogeneous catalysis, however, studies on its applications in electrocatalysis are still insufficient. Herein, it is reported that W 18 O 49 nanowires supported sub‐nanometric Ru clusters (denoted as Ru SNC/W 18 O 49 NWs) constitute an efficient bifunctional electrocatalyst for hydrogen evolution/oxidation reactions (HER and HOR) under acidic condition. Microstructural analyses, X‐ray absorption spectroscopy, and density functional theory (DFT) calculations reveal that the Ru SNCs with an average RuRu coordination number of 4.9 are anchored to the W 18 O 49 NWs via RuOW bonds at the interface. The strong metal‐support interaction leads to the electron‐deficient state of Ru SNCs, which enables a modulated RuH strength. Furthermore, the unique proton transport capability of the W 18 O 49 also provides a potential migration channel for the reaction intermediates. These components collectively enable the remarkable performance of Ru SNC/W 18 O 49 NWs for hydrogen electrocatalysis with 2.5 times of exchange current density than that of carbon‐supported Ru nanoparticles, and even rival the state‐of‐the‐art Pt catalyst. This work provides a new prospect for the development of supported sub‐nanometric metal clusters for efficient electrocatalysis.