Fundamental Insights into the Covalent Silane Functionalization of NiFe‐Layered Double Hydroxides

Layered double hydroxides (LDHs) are a class of 2D anionic materials exhibiting wide chemical versatility and promising applications in different fields ranging from catalysis to energy storage and conversion. However, the covalent chemistry of this kind of 2D materials is still barely explored. Herein, we report the covalent functionalization with silanes of a magnetic NiFe-LDH. The synthetic route consists of a topochemical approach followed by the anion exchange reaction of a surfactant molecules prior to the covalent functionalization with the (3-aminopropyl)triethoxysilane (APTES) molecules. The functionalized NiFe-APTES was fully characterized using X-ray diffraction, infrared spectroscopy, electron microscopy, thermogravimetric analysis coupled with mass spectrometry and 29Si solid state nuclear magnetic resonance, among others. The effect on the electronic properties of the functionalized LDH was studied by a magnetic study in combination with Mossbauer spectroscopy. Moreover, the reversibility of the silane-functionalization at basic pH was demonstrated, and the quality of the resulting LDH proved by studying the electrochemical performance in the oxygen evolution reaction in basic media. Furthermore, the anion exchange capability for the NiFe-APTES was tested employing Cr(VI), resulting in an increase of 200 % of the anion retention. This report allows a new level in the tunability of LDHs opening the door to the synthesis of new hybrid materials and architectures.