Giant enhancement of coercivity in β-Ni(OH)2 decorated Ti3C2Tx MXene nanosheets

Abstract

Ti3C2Tx MXenes are of great interest due to their high conductivity, easy synthesis and unique functional properties. Functionalisation and structural engineering are essential for various applications because of their dramatic influences on different chemical and physical properties. Therefore, understanding the mechanism of the etching reaction of Ti3C2Tx from its parent MAX phase is crucial. The structural details also need to be understood for application in different practical devices. In this study, 2D Ti3C2Tx sheets with an average thickness of 3.48 nm and lateral dimension of 5.5 μm were synthesised by removing Al layers from the Ti3AlC2 MAX phase. The step-by-step etching mechanism was analysed with the help of Rietveld refinement of the powder x-ray diffraction data. The structural details and influence of different functional groups on the surface were also studied using transmission electron microscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy. The magnetic behaviour and magnetic interaction of bare 2D Ti3C2Tx decorated with β-Ni(OH)2 nanosheets on its surface was studied. For the bare 2D Ti3C2Tx MXene sheets, a weak ferrimagnetic ordering with negligible coercivity was found. However, the β-Ni(OH)2-decorated Ti3C2Tx MXene sheets exhibit strong ferrimagnetic ordering with a sufficiently large coercivity of 0.2 T at 2 K and a transition temperature of 246 K. The generation of this interfacial ferrimagnetism is discussed in light of the interfacial charge transfer originating from d-p mixing. These 2D magnets generated at the interface could be useful for application in different spintronic devices.