Fluorine-free synthesis of ultra-thin, high aspect ratio Ti3C2Tx MXene nanosheets for high-efficiency ultraviolet-shielding applications

Abstract

MXenes, two-dimensional transition metal carbides and nitrides, show great potential in various applications. However, traditional synthesis methods often involve toxic fluorine-containing etchants, limiting large-scale production. This study introduces a novel, environmentally friendly approach for synthesizing Ti3C2Tx MXene nanosheets using stone grinding-assisted exfoliation and mild alkaline etching at 80°C. The synthesized MXene nanosheets exhibited high aspect ratios with transverse dimensions mostly on the micrometer scale and a thickness of approximately 3 nm, corresponding to one to two layers of Ti3C2. MXene/polyvinyl alcohol (PVA) composite membranes were fabricated to demonstrate practical applications. The composite membrane containing 1 wt% MXene achieved a 99.9% UV shielding rate while maintaining 67% visible light transmittance. Furthermore, it significantly enhanced PLA's UV resistance, with protected samples retaining 98.1% tensile strength after 48 hours of UV exposure, compared with 47.8% for unprotected PLA. This fluorine-free synthesis method addresses environmental concerns and enables large-scale MXene production for advanced UV protection applications. Highlights: Ti3C2Tx MXene is made via stone grinding and alkaline etching. MXene nanosheets are produced in the micron range and are 1–2 layers thick. The fluorine-free synthesis enables green, large-scale production of MXene. MXene/PVA films show 99.99% UV shielding with 67% visible light transmittance. MXene/PVA coating improves PLA's UV resistance, keeping 98.1% of tensile strength.