Crystal‐Phase Engineering of Iridium‐Embedded Tungsten for Hydrogen Oxidation Electrocatalysis

Abstract Understanding the phase structure‐dependent catalytic performance is of great significance for the investigation of advanced electrocatalysts. At present, research in phase engineering of metal materials for electrocatalysis predominantly concentrates on the iron group, platinum group, and coinage group metals with A1‐, A2‐, and A3‐ type structures. However, the investigation of metal phase engineering beyond the above metal group with other types of structures for electrocatalysis is still poorly explored. Herein, using tungsten as a substrate to support iridium, it is shown that iridium‐embedded tungsten with diverse crystal phase structure (referred to as Ir/α‐W for A2‐type structure and Ir/β‐W for A‐15 type structure) exhibits distinct catalytic activity for hydrogen oxidation reactions (HOR) in alkaline medium. Notably, the mass‐normalized exchange current density (j 0, m ) of noble metal iridium in Ir/α‐W (518.3 A g −1 Ir ) is ≈1.8 times and 16.4 times higher than that of Ir/β‐W and Ir/C, respectively. In‐depth mechanistic studies suggest that the enhanced HOR performance on Ir/α‐W is attributed to the enhanced connectivity of the H‐bond network as well as the synergistic optimization of the adsorption binding energies of H and OH intermediate species. This study can inspire more scientific interest on the exploration of metal phase engineering for electrocatalysis.