Unveiling the Critical Role of Surface Oxidation of Electroresponsive Behaviors in Two-Dimensional Ti₃C₂T_x MXenes

Abstract

Here, two-dimensional (2D) C/TiO2 hybrids synthesized via oxidation of Ti3C2T x MXenes are reported as an ideal electrorheological (ER) candidate in pursuit of high ER efficiency. The lamellar structure of conductive carbon layers provides abundant electron transport channels, aiming to shorten the response time to an electric field, while the TiO2 nanoparticles deliver high surface polarization leading to high ER effects. The oxidation degrees of Ti3C2T x MXenes are systematically controlled through the hydrothermal method (h-C/TiO2) or CO2 calcination (c-C/TiO2). We comprehensively studied the relationship between the surface oxidation and ER behaviors of these C/TiO2 hybrids. It was found that the h-C/TiO2 hybrid exhibited superior ER behaviors compared with the c-C/TiO2 hybrid. The holey h-C/TiO2 architecture creates large electron and oil transport pathways, which is responsible for the superior ER performances. Overall, this research provides original insights into the exciting electroresponsive materials of this quickly growing 2D MXene family as well as provides a guideline for processing oxidation of MXenes for diverse applications.

Is Chitosan the Promising Candidate for Filler in Nature-Friendly Electrorheological Fluids?

“…In the studied chitosan suspension, the authors observed a transition from a quadratic dependence to one and a half at 1 kV/mm. A similar transition was observed for several systems and was associated with a change in the mechanism of the electrorheological effect. ,− The conductive mechanism was also involved in addition to polarization. , …”

Synthesis and Electronic Structure of a 3D Crystalline Stack of MXene-Like Sheets

“…In general, MXenes have been considered stable in air and water; however, growing evidence reveals that MXenes decompose over the course of a few days to a few weeks. − For example, Ti 3 C 2 (−O, −OH, −F) decomposes to form TiO 2 in the presence of oxygen , and water. , In fact, the etching synthetic method, which uses strong oxidants like HF, H 2 O 2 , or HCl/LiF, contributes to the oxidation, as evidenced by the formation of −O terminating moieties. The oxidation has consequences on the electronic structure . For example, the work function of Ti 3 C 2 (−O, −OH, −F) was predicted to vary from 1.9 to 6.2 eV depending on the surface terminations .…”

“…The oxidation has consequences on the electronic structure. 74 For example, the work function of Ti 3 C 2 X (X = -O, -OH, -F) was predicted to vary from 1.9 to 6.2 eV depending on the surface terminations. 75 Moreover, the work function of MXenes with random surface moieties depends on the complex interplay between the different surface moieties and their local dipoles.…”

Controlling the Surface Reactivity of Hybrid Ti3CN MXene via In‐situ Electrocatalysis

“…[4][5][6][7] MXenes are a family of 2D transition metal carbides, nitrides, and carbonitrides which have demonstrated promising electrochemical performance for HER. [8][9][10][11][12][13][14][15][16][17][18][19][20] Their general formula is M n + 1 X n T x (n = 1-4), where M represents an early transition metal (such as Ti, Mo, V, etc. ), X represents carbon and/or nitrogen, and T x represents the surface termination groups (typically À OÀ , À OH and/or À F).…”

“…MXenes are a family of 2D transition metal carbides, nitrides, and carbonitrides which have demonstrated promising electrochemical performance for HER [8—20] . Their general formula is M n+1 X n T x (n=1‐4), where M represents an early transition metal (such as Ti, Mo, V, etc.…”