Size‐Dependent Electrochemistry of Oxygenated Ti₃C₂T_x MXenes

Abstract

2D MXenes are widely proved to be potential electrode materials, although the size effect on their electrochemistry is not fully understood. In this work, Ti 3 C 2 T x nanoflakes are prepared through acidic etching of Ti 3 AlC 2 powders, followed by the intercalation treatment with tetrapropylammonium hydroxide. Such a method produces large-scale delaminated and oxygenated nanoflakes. With aid of centrifugation, the nanoflakes with varied lateral sizes and thicknesses are collected, where electrochemical response of charged redox probes and polar phenol molecules is varied. Density functional theory and energy dispersive spectroscopy confirm such electrochemical response is dependent on the size and thickness of used nanoflakes, more exactly the oxygen content on their surface. Taking the nanoflakes obtained using a centrifugal speed of 5000 rpm (MX-TPA 0.2 ) as an example, they feature good dispersibility, a high oxygen content, a small size, and a thin thickness. On these nanoflakes electrochemical response of polar p-substituted phenols is pronounced, stemming from a strong electron-withdrawing interaction of their oxygenated termination with the Ar-OH. A sensitive electrochemical sensor is further constructed for the detection of p-nitrophenol. This work thus provides an approach to synthesize MXenes with different sizes and thicknesses as well as further to reveal size-dependent electrochemistry of MXenes.

Simple and sensitive fluorescence sensing of methyl parathion based on the inner filter effect of p‐nitrophenol on nitrogen‐doped titanium carbide quantum dots

“…The N-Ti 3 C 2 QDs was obtained according to previously reported research with slight modification [27]. Typically, 15.0 mg Ti 3 C 2 multilayer was added to 15.0 mL DMF, then the mixture was sonicated for about 1 h. After that, ammonium hydroxide was dropwise added into the reaction solution to adjust the pH value to around 9.0.…”

“…Recently, fluorescence sensors based on IFE have been confirmed to be an ideal strategy in tracking detection due to its simplicity and easy fabrication [20,21]. The detection procedure in this type of system is usually realized through a pair of suitable fluorophore-absorber with good overlapping spectra [22,23] nanosheets, which significantly expands their potential applications in biosensing, biomedicine and environment [26,27]. Furthermore, Ti 3 C 2 QDs doped with heteroatoms are very important adjusted methods to enhance the optical and electrochemical features, further inducing the increased surfaced performance of Ti 3 C 2 QDs, that is, stronger fluorescence properties, higher quantum yield, more active-sites, better solubility and stability [28].…”