Contrasting Photochemical Activity of Two Sub-layers for Natural 2D Nanoclay with an Asymmetric Layer Structure

The two-dimensional (2D) materials with asymmetric sub-layers have recently attracted tremendous interest in many fields, and investigating the structure–performance relationship of different sub-layers is critical but challenging. Herein, we report that natural kaolinite (Kaol) nanosheets with an asymmetric layer structure possess a contrasting photocatalytic activity on its Al–O and Si–O sub-layers. The experimental and theoretical results reveal that the ion isovalent structure of Fe3+ and Al3+ not only results in a high iron doping concentration in the Al–O sub-layer but also causes superb intrinsic photochemical activity of the Al–O sub-layer compared with the Si–O sub-layer. Thus, the Al–O sub-layers of Kaol NSs have more excellent photogenerated charge generation and separation efficiency than Si–O sub-layers, resulting in about 1–2 orders of magnitude higher photocatalytic performance. This study not only unravels the structure–performance relationship of different sub-layers of 2D nanoclay but also sheds new light on the design of 2D materials with the asymmetric sub-layer.