Surface Functionalization of Single-Layered Ti₃C₂T_x MXene and Its Application in Multilevel Resistive Memory

Abstract

MXenes are a new type of two-dimensional material, and they have attracted extensive attention because of their outstanding conductivity and rich surface functional groups that make surface engineering easy and possible for adapting to diverse applications. However, there are scarce studies on surface engineering of MXene. Herein, we demonstrate for the first time that octylphosphonic acid-modified Ti 3 C 2 T x MXene can be used as an active layer for memory devices and exhibits stable ternary memory behavior. Low threshold voltage, steady retention time, clearly distinguishable resistance states, high ON/OFF rate, OFF/ ON1/ON2 = 1:10 2.7 :10 4.1 , and considerable ternary yield (58%) were obtained. In the proof of the mechanism, in situ conductive atomic force microscopy was conducted and the electrode-area relationship was analyzed to demonstrate that charge trapping and filament conduction are more suitable in the nonvolatile information memory of Ti 3 C 2 T x -OP MXene devices. In addition, a polyethylene-terephthalate-based flexible Ti 3 C 2 T x -OP memory device can maintain its stable ternary memory performance after being bent 5000 times. This work provides an easy method for surface modification of MXene and broadens the field of MXene.

Built‐in Electric Field Triggered Interfacial Accumulation Effect for Efficient Nitrate Removal at Ultra‐Low Concentration and Electroreduction to Ammonia

“…[15] Ti 3 C 2 T x MXene aqueous solution was prepared by etching Ti 3 AlC 2 power using LiF in concentrated HCl and it comprised Ti 3 C 2 monolayers terminated by OH and Cl groups. [16] TheM Xene surfaces were negatively charged (Supporting Information Table S2) after release of H + groups,a nd thus,p ositive Cu 2+ ions were adsorbed, reduced and precipitated. Adark precipitate was produced from Ti 3 C 2 T x MXene dispersion after adding CuSO 4 solution dropwise.T ransmission electron microscopy (TEM) and high-angle annular dark field image (HAADF) scanning TEM imaging (Insert in Figure 3a)show that the nanoshuttles comprised the uniform distribution of Ti,C u, O, and Cl on the MXene layers (Figure 3a and Supporting Information Figure S5).…”

Engineering Aggregation‐Resistant MXene Nanosheets As Highly Conductive and Stable Inks for All‐Printed Electronics

“…[16] MXenes prepared by adopting organic phosphonic acids as the ligands have been reported, but have shown decreased levels of conductivity, for example, of ≈1000 S cm −1 , much lower than those of pristine MXene (5000 S cm −1 ). [14,17] Therefore, a new chemical approach would appear to be required to improve the printability of MXene nanosheets and make them compatible with high-tech direct printing.…”

Tuning the Magnetic Properties of Two-Dimensional MXenes by Chemical Etching

“…2°) compared to the unetched Ti3AlC2, indicating Al is replaced by -F or -OH moieties specially near the surface region 44,47. Some Ti3AlC2 peaks are still observed in Ti3AlC2 Batch 1 indicating the presence of some unreacted MAX phase in the bulk after the etching process.…”