スーパー格子セリウムニッケル金属間化合物の水素誘起非晶質化による効率的なアルカリ酸素発生反応の実現

Transforming intermetallics with highly ordered structures into amorphous forms to unlock their superior oxygen evolution reaction (OER) remains a significant challenge. This study introduces a hydrogen-induced amorphization approach, where hydrogen triggers severe lattice mismatches between subunits in the superlattice-structured CeNi₃ intermetallic, resulting in its amorphization. This process notably enhances its alkaline OER performance. Remarkably, the amorphized CeNi₃ requires a mere 318 mV of overpotential to drive 100 mA cm^-2, which is approximately 40 mV lower than its crystalline counterpart. Additionally, it sustains stable operation at about 620 mA cm^-2 for 200 h in 1.0 m KOH. Comprehensive characterizations, including X-ray absorption spectroscopy, in situ Raman spectroscopy, in situ differential electrochemical mass spectroscopy, density functional theoretical calculations, and post-OER analyses, reveal that the amorphized CeNi₃ undergoes a favorable surface reconstruction process, forming a Ce-doped NiOOH active phase that follows the adsorbate evolution mechanism, thereby enhancing both the OER activity and durability of the material. The gaseous hydrogen engineering strategy outlined here offers valuable insights for designing novel rare earth-transition metal-based electrocatalysts, paving the way for advancements in this emerging field of electrocatalysis.