Noncovalent functionalization of Ti3C2TX using cationic porphyrins with enhanced stability against oxidation

Abstract

Ti₃C₂T_X, as the most explored MXenes, are a rising star among 2D materials due to their astonishing physicochemical properties. However, their practical applications remain extremely challenging because of chemical degradation into TiO₂ nanoparticles due to oxidation. Chemical functionalization is an effective way to improve their stability against oxidation and tune the physicochemical properties of 2D materials. In this paper, Ti₃C₂T_X is noncovalently functionalized using two different cationic porphyrins and the two hybrids show good stabilities in water against oxidation. The electrostatic interactions between the cationic porphyrins and the Ti₃C₂T_X nanosheets are confirmed by the changes in the zetapotential and the photophysical measurements. The hybrids show a red shifted Soret band of the porphyrins with a complete quenching of the fluorescence emission, which confirms the effective interactions and an energy/electron transfer between the porphyrins and the Ti₃C₂T_X nanosheets. The exfoliated and functionalized Ti₃C₂T_X are characterized using various microscopic and spectroscopic techniques. The two hybrids exhibit pH dependent release of cationic porphyrins particularly under acidic conditions. This study proposes a potentially useful strategy for the preparation of highly stable and functional MXenes towards promising applications in biomedicines, optoelectronics and sensors.