Reaction mechanism of exfoliation degree and high temperature surface oxidation metamorphism of 2D Ti3C2Tx on thermal decomposition of various energetic materials

Achieving higher and faster energy release processes is a major research goal for energetic materials (EMs). Typically, EMs enhance their overall performance by incorporating catalysts. The novel two-dimensional layered MXenes, such as Ti3C2Tx, have shown significant potential as additives for ammonium perchlorate (AP). However, there is limited research on the impact of the exfoliation degree and high temperature oxidation of Ti3C2Tx MXene catalyst on the pyrolysis and combustion of different types of EMs. In this study, ultrathin Ti3C2Tx (U-Ti3C2Tx) MXene with a high exfoliation degree of approximately 20-80 nm was obtained through hydrofluoric acid (HF) etching, dimethyl sulfoxide (DMSO)-assisted layer expansion and ultrasonic peeling. The catalytic performance of MXenes on the thermal decomposition of three types of EMs (dihydroxylammonium 5, 5 '- bistetrazole-1, 1 '-diolate (TKX-50), cyclotetramethylene tetranitroamine (HMX), and AP) was evaluated. Results showed that 4 wt% U-Ti3C2Tx can reduce the decomposition peak of TKX-50 by 33.6 degrees C and decreases the high temperature decomposition (HTD) peak of AP by 45.5 degrees C, indicating superior catalytic performance compared to non-exfoliated Ti3C2Tx MXene. However, it had insignificant effect on HMX. Surface chemical analysis, electrochemical characterization, thermal decomposition of gaseous products analysis and material studio simulation all confirmed that high exfoliation U-Ti3C2Tx MXene exhibited better stability and electrical conductivity, facilitating the acceleration of the H+ transfer process and rapid gas release from EMs. Additionally, ignition tests demonstrated that high exfoliation U-Ti3C2Tx could effectively participate in the ignition process of EMs. The characterization and thermal analysis of Ti3C2Tx products after high temperature and oxidation treatment indicated that the catalytic activity is weakened due to high temperature crystal collapse and surface oxidation to TiOx metamorphism. This study provides new insights for the application of MXene catalysts in EMs.