Fe-doping induced localized amorphization in ultrathin α-Ni(OH)2 nanomesh for superior oxygen evolution reaction catalysis

Abstract

Local structure and crystallinity have been confirmed to be critical in the catalytic activity of catalysts, and the formation of amorphous phase can afford significantly enhanced catalytic performance. The controlled distribution of amorphous phase at the nanoscale in materials, however, remains a substantial challenge, which results in the absence of an underlying relationship between the amorphization level and the catalytic activity. In this work, we successfully realize identified amorphization of ultrathin two-dimensional α-Ni(OH)₂ nanomeshes through Fe doping, by which the amorphization rates can be controlled over 10–78% in area ratios with the desired amount of Fe doping. The localized amorphization dramatically accelerates the reaction kinetics and thus enhances the overall performance for the oxygen evolution reaction (OER). Specifically, a strong correlation between the OER activity and the amorphization rate is discovered, and α-Ni_0.75Fe_0.25(OH)₂ with the highest amorphization rate of 78% achieves the highest catalytic activity. The enhanced catalytic activity is dominantly attributed to the doping-induced localized amorphization, which provides more accessible active sites and responsible local chemical environments than the fully crystallized structures. The understanding of the amorphization-catalytic activity relationship thus provides new insight into developing highly efficient catalysts.