Research On Preparation And Performance Of Mxene-Based Triboelectric Nanogenerators Materials

As the environmental issues such as the global energy crisis and climate change become increasingly urgent,there is an urgent need to develop clean and renewable energy sources to gradually replace fossil fuel.In recent years,the emerging triboelectric nanogenerator based on contact electrification and electrostatic induction coupling has been proven to be an economical,effective,and simple power generating device that can directly convert mechanical(wind,ocean,body movement et al.)energies into electricity.Its huge application potential has attracted great attention from scientists.In the past few years,TENG's working mode,device structure,energy management and optimization have been greatly improved and expanded.However,before TENG replaces traditional energy sources,its low output power is still a primary issue that needs to be resolved.The output performance of the triboelectric nanogenerator largely depends on the properties of the triboelectric material,especially the inherent microstructure and functional groups of the material.It is worth noting that the MXene is an emerging group of two-dimensional transition metal carbide or nitride,which has a number of functional groups(-F,-O,-OH)on its surface that can provide it high electronegativity.These functional groups are beneficial to capture more electrons to increase the surface charge density of the material,and therefore have the potential to become a triboelectric nanogenerator material.Looking into the high electronegativity characteristics of MXene,the research of the MXene triboelectric nanogenerator materials has been launched.And the following results have been achieved.1.Nb₂CT_x and Ti₃C₂T_x nanosheets are self-assembled into a Ti₃C₂T_x/Nb₂CT_x alternate-layered MXene composite film.The obtained film has uniformed microstructure and abundant-F functional groups.The Nb₂CT_x can effectively reduce the self-accumulation of Ti₃C₂T_x nanosheets,increase the interlayer spacing of Ti₃C₂T_x nanosheets,and provide more effective nanochannels for-F functional groups.2.The Ti₃C₂T_x/Nb₂CT_x composite films selected as the negative friction layer of triboelectric nanogenerator to study its triboelectric properties.Both Nb₂CT_x and Ti₃C₂T_x contain a large amount of-F functional groups,thus the introduction of a small amount of Nb₂CT_x can significantly increase the surface charge density of Ti₃C₂T_x/Nb₂CT_x alternate-layered MXene composite film.When the amount of the Nb₂CT_x nanosheets increases to 15 wt%,the current density and voltage of the triboelectric nanogenerator were 8.1?A/cm² and 34.6V,respectively,which are 840%and 350%of the purified Ti₃C₂T_x film,and are410%and 420%of the polytetrafluoroethylene(PTFE)film.At the same time,the triboelectric nanogenerator mentioned above can be fixed on the skin to collect energy from simple movements.3.Here,a Ti₃C₂T_x/polyvinyl alcohol and agarose hydrogel(Ti₃C₂T_x/PVA-AG)TENG is presented with simple fabrication,high output performance,and flexible applications.The doping of Ti₃C₂T_x nanosheets promotes the crosslinking of the PVA hydrogel and improves the stretchability and self-healing of the composite hydrogel.Simultaneously,an extra triboelectric output ascribed to the addition of Ti₃C₂T_x,the electron trapping ability of the silicone rubber friction layer is enhanced.The measured open-circuit voltage of the Ti₃C₂T_x/PVA-AG hydrogel TENG reaches up to 125V even in a single-electrode mode.The Ti₃C₂T_x/PVA-AG hydrogel TENG can be stretched up to 250% of the original length and demonstrates a monotonical increasing relationship between the stretchable length and the short-circuit voltage.By utilizing the Ti₃C₂T_x/PVA-AG hydrogel TENG's outstanding stretchable property and ultrahigh sensitivity to mechanical stimuli,applications in wearable movement monitoring,and low-frequency mechanical energy harvesting are demonstrated.