Homogeneous Metastable Hexagonal Phase Iridium Enhances Hydrogen Evolution Catalysis.

ABSTRACT: Catalytic reactions are surface-sensitive processes. Fabrication of homogeneous metastable metals can be used to promote phase-dependent catalytic performance; however, this has been a challenging task. Herein, homogeneous metastable hexagonal close-packed (hcp) Ir is epitaxially grown onto metastable phase hcp Ni, as demonstrated using spherical aberration electron microscopy. The as-fabricated metastable hcp Ir exhibits high intrinsic activity for the alkaline hydrogen evolution reaction (HER). In particular, metastable hcp Ir delivers a low overpotential of 17 mV at 10 mA cm^-2 and presents a high specific activity of 8.55 mA cm^-2 and a high turnover frequency of 38.26 s^-1 at -0.07 V versus the reversible hydrogen electrode. Owing to its epitaxially grown structure, metastable hcp Ir is highly stable. Theoretical calculations reveal that metastable hcp Ir promotes H₂ O adsorption and fast H₂ O dissociation, which contributes to its remarkable HER activity. Findings can elucidate the crystal phase-controlled synthesis of advanced noble metal nanomaterials for the fundamental catalytic applications.

SUBMITTER: Geng S 

PROVIDER: S-EPMC10104624 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature