| 초록 |
Ni-Fe layered double hydroxides (LDH) are active materials used for oxygen evolution reaction (OER) in alkaline environments. In this study, a facile and scaling up synthesis route using a surfactant for ultrathin Ni-Fe LDH nanosheets was newly proposed. We clarified the role of the surfactant in triggering the ultrathin nanosheet evolution. A hidden phase transformation mechanism of the Ni-Fe LDH was also uncovered by combining in-situ/operando X-ray absorption spectroscopy, X-ray diffraction, and energy dispersive spectroscopy. The Ni-Fe LDH underwent a chemically induced phase transformation in an alkaline environment without applied electrical potential. The resulting phase transformation product persisted throughout the entire OER cycle, such that it played a dominant role in the process. The presence of high-valent Ni and Fe was observed on the surface, hence, the OER selectivity and catalytic turnover frequency were enhanced in the low overpotential domain. We attributed this enhancement to the ultrathin nanosheet form of the LDH and resulting surface property. |
