Dual cross-linked MXene/cellulose nanofiber/nickel alginate film with improved mechanical properties and electromagnetic interference shielding performance

Electromagnetic interference pollution has raised urgent demand for the development of electromagnetic interference shielding materials.Transition metal carbides(MXenes)with excellent conductivity have shown great potential in electromagnetic interference(EMI)shielding materials,while the poor mechanical strength,flexibility,and structural stability greatly limit their further applications.Here,cellulose nanofibers and sodium alginate are incorporated with MXene nanosheets as flexible matrices to construct strong and flexible mussellike layered MXene/Cellulose nanofiber/Sodium Alginate composite films,and nickel ions are further introduced to induce metal coordination crosslinking of alginate units.Benefited from the dual-crosslinked network structure of hydrogen bonding and metal coordination,the tensile strength,Young’s modulus,and toughness of the MXene/cellulose nanofiber/nickel alginate composite film are significantly increased.After subsequent reduction by ascorbic acid,excess nickel ions are reduced to nickel nanoparticles and uniformly dispersed within the highly conductive composite film,which further improved its hysteresis loss effect toward the incident electromagnetic waves.Consequently,the MXene/cellulose nanofiber/nickel alginate-Ni composite film presents a considerably enhanced electromagnetic interference shielding effectiveness(47.17 dB)at a very low thickness of 29μm.This study proposes a feasible dual-crosslinking and subsequent reduction strategy to synergistically enhance the mechanical properties and electromagnetic interference shielding performance of MXene-based composite materials.

Shear stress-induced delamination method for the mass production of Ti_(3)C_(2)Tx MXene nanosheets

MXene nanosheets are considered advantageous for functional materials,but current delamination methods to prepare MXene nanosheets have many limitations including high cost,small production scale,low efficiency,and deteriorated structure integrity of obtained nanosheets.Here,we propose a simple,efficient,and scalable shear stress-induced delamination(SSID)strategy to boost the production of single-/few-layered Ti_(3)C_(2)T_(x) MXene nanosheets.Molecular dynamics simulation indicates that the pan mill-type grinding discs create a strong hydrodynamic flow field,which exerts gigantic shear stress to substantially delaminate the multilayered MXene stacks into homogeneously dispersed MXene nanosheets.Furthermore,shear stress generated from vigorous water flow has limited fragmentation effect,ensuring large lateral size and good structure integrity to the obtained MXene nanosheets as evidenced by the morphological and structural characterizations.Compared to conventional delamination methods,this novel SSID strategy exhibits great advantages in terms of efficiency,scalability and the properties of resultant MXene nanosheets,which opens up great opportunity for the scalable production and commercialization of high-performance MXene-based materials.