Multifunctional composite catalysts show significant potential for enhancing the thermal decomposition and combustion of energetic materials. However, their synergistic mechanisms remain unclear. In this work, we prepared a 3D macroporous (3DM) CuO/ZnO catalyst via PMMA template calcination and combined it with Ti 3 C 2 T x MXene through electrostatic assembly, to form a 3DM CuO/ZnO-Ti 3 C 2 T x heterogeneous catalyst with uniform morphology and high conductivity. Results show that 3DM CuO/ZnO-Ti 3 C 2 T x has a good catalytic effect on TKX-50, which can advance the decomposition peak from 246 to 208 ℃, increase the heat release from 730 to 1106 J/g and boost combustion time from 560 to 790 ms, improve the flame temperature from 773 to 1109 ℃. By combining LAMMPS, materials studio software and TG-MS-IR analysis, the catalytic mechanism of 3DM material on the thermal decomposition of TKX-50 was deeply explored. 3DM materials can adsorb hydroxylamine molecule, accelerate the H + transfer process, achieve rapid exchange of H and OH, and realize the rapid and concentrated release of gas, thereby promoting the decomposition process of TKX-50. Consequently, the construction of composite catalysts with synergy can start from the perspective of forming more heterostructures, which provides better theoretical support for future research on composite catalysts.
Developing the multi-functional membranes including oil/water emulsion separation and removal of hazardous organic pollutants is essential to the purification of the complicated wastewater. However, it remains a daunting challenge to combine these intended functions while maintaining high separation efficiency. Herein, we developed a new 2D lamellar MXene/poly (arylene ether nitrile) (PEN) fibrous composite membrane through the self-assembly of TiO 2 nanoparticles intercalated MXene nanosheets onto the porous PEN nanofibrous mats and bioinspired polydopamine triggered chemical-crosslinking with polyethyleneimine (PEI). Such nano-intercalation and mussel-inspired crosslinking could effectively regulate the interlayer spacing of the MXene nanosheet skin layer and surface wettability of the composite membrane, which also further contributed to the fast separation and unique bifunctional feature. It was found that the MXene@TiO 2 /PEN fibrous composite membrane exhibited low oil-adhesion and superhydrophilic (WCA = 0°)/underwater superoleophobic (UOCA > 155°) properties, which could efficiently separate various surfactant-stabilized oil-in-water emulsions under low pressure of 0.04 MPa while keeping good stability (Under 1 M HCl and 2 M NaOH solutions) and recyclability. Interestingly, the fibrous composite membrane achieved favorable permeation flux of 908–1003 Lm −2 h −1 (2270–2507.5 Lm −2 h −1 bar −1 ) in comparison to other reported MXene based multifunctional composite membranes. Moreover, owing to the synergistic effect of MXene nanosheets and TiO 2 nanoparticles, the MXene@TiO 2 /PEN membrane showed excellent photocatalytic degradation performance for various dyes under visible light, i.e. the photocatalytic degradation efficiency for 15 ppm MB, MO, CV, and MeB solutions achieved 92.31%, 93.50%, 98.06%, and 99.30% within 60 min, respectively. Such 2D MXene bio-functional composite membranes with outstanding oil/water emulsions separation and photocatalytic degradation of dyes pave an avenue for treating complicated oily wastewater.
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