Enhanced photoluminescence emission and pH sensitivity in oxygen-dominated functional group of highly stable Ti3C2Tx MXene

Transition metal carbides, commonly known as MXenes, represent a promising family of two-dimensional nanomaterials characterized by diverse surface functional groups that vary with the synthesis method. This study investigates the enhanced luminescence of MXene nanosheets, increasing photoluminescence intensity due to improved charge transfer, and the influence of pH on the photoluminescence excitation spectrum of ${\mathrm{Ti}}_3{C}_2{T}_x$ MXene, which features oxygen-dominated functional groups. The ${\mathrm{Ti}}_3{C}_2{T}_x$ MXene was well-synthesized using hydrofluoric acid (HF), as confirmed with X-ray diffraction analysis, which revealed the hexagonal structure of ${\mathrm{Ti}}_3{C}_2{T}_x$ with a crystallite size of 3.8 nm, while electron microscopy images illustrated its distinct layered morphology with the inter-layer spacing of 1.13 nm which reveals good flexibility and tensile strength of the MXene. Photoluminescence studies demonstrated significant light emission with enhanced photoluminescence intensity with varying excitation wavelength in the blue–green region, spanning from 400 nm to 690 nm. Notably, pH-dependent photoluminescence analysis indicated a decrease in excitation intensity at pH 2, suggesting a loss of the material’s intrinsic properties under acidic conditions. Furthermore, cyclic voltammetry and zeta potential reveal outstanding stability of MXene over time. The electrical measurement reveals the semiconducting nature of ${\mathrm{Ti}}_3{C}_2{T}_x$, which is evident from its band gap. This research highlights the critical role of pH in modulating the optical properties of ${\mathrm{Ti}}_3{C}_2{T}_x$ MXene, paving the way for potential applications in optoelectronic devices and sensors.