Le Li,Hongyu Liu,Xiaoqiang Fan,Zhengfeng Cao,Lining Wu,Xiangyuan Ye
A single Ti 3 C 2 T x is not sufficient to meet the dispersing stability and lubricating performance requirements of lubricating oil in complex working conditions. Environmentally friendly high-performance Ti 3 C 2 T x composite lubricating oil additives combine the advantages of Ti 3 C 2 T x and other materials and have a promising long-term high-efficiency lubricating prospect. In this study, Ti 3 C 2 T x /SiO 2 heterostructures were prepared as lubricant additives to enhance the tribological performance of PAO20. Tribological tests indicate that the addition of 0.15 wt% Ti 3 C 2 T x /SiO 2 heterostructures reduced the average wear volume by 65.9 % at 392 N due to the synergistic effect of Ti 3 C 2 T x and SiO 2 . The excellent lubricating performance of Ti 3 C 2 T x /SiO 2 heterostructures is primarily attributed to the rolling effect of SiO 2 and the dual friction mechanism of Ti 3 C 2 T x /SiO 2 friction film during synergistic friction. The Ti 3 C 2 T x /SiO 2 friction film and SiO 2 enhance the interface load-bearing capacity and anti-friction/wear performance. This structural design of Ti 3 C 2 T x /SiO 2 heterostructures provides a new perspective for the design of Ti 3 C 2 T x composite lubricant additives .
Polyimide (PI) is a special engineering plastic, widely involved in mechanical components, instruments, and petrochemicals. However, single PI material is inevitably subject to wear and tear in practice, which leads to weakened material properties. In this work, Ti 3 C 2 T x @SiO 2 was prepared to enhance the wear resistance and lubrication properties of PI by intercalating SiO 2 into the interlayer of Ti 3 C 2 T x sheets. Ti 3 C 2 T x @SiO 2 /PI composites were fabricated in two steps to test the tribological performances. SiO 2 particles change the form of interfacial friction from sliding to rolling, thus relieving direct friction between material and steel ball. So, the composites have a minimum COF (COF = 0.33) when the content of Ti 3 C 2 T x @SiO 2 is 0.80 wt%. Moreover, the average value of wear rate was 0.24 × 10 −5 mm 3 /(N·m) when Ti 3 C 2 T x @SiO 2 content was 1.60 wt%, which was 91.0% lower compared to the PI matrix. During the friction process, the abrasive chips of the material migrate to the surface of the steel ball to form a transfer film, which protects the material and thus reduces the wear rate. Therefore, the hybrids Ti 3 C 2 T x @SiO 2 are effective and important wear-resistant agents and solid lubricants to improve the wear resistance and lubricity of PI or other polymer materials. Highlights SiO 2 insert Ti 3 C 2 T x is a key factor in changing sliding friction into rolling friction, effectively reducing the COF. The average wear rate was 91.0% lower than that of the polyimide matrix when Ti 3 C 2 T x @SiO 2 content was 1.60 wt%. The minimum COF of Ti 3 C 2 T x @SiO 2 /PI composites reached 0.33 when the content of Ti 3 C 2 T x @SiO 2 was 0.80 wt%. The transfer film effectively reduces further wear of the material during friction.
Menglei Mao,Ruqing Chong,Feixue Sun,Rui Gao,Zihui Meng,Xinlong Fan,Wenfang Liu
Enzymatic conversion of CO 2 to formate is a highly significant pathway for CO 2 utilization, but current level of conversion efficiency remains unsatisfactory due to low solubility of CO 2 under mild conditions. CO 2 -philic materials can significantly augment the reaction by raising local concentration of substrate. Herein, the intercalated Ti 3 C 2 T x , nano-silica (SiO 2 ) and carbon nitride (CN) with abundant CO 2 adsorption sites were introduced to fabricate Ti 3 C 2 T x based nanocomposites, Ti 3 C 2 T x /SiO 2 /CN (TSCN), for the first time. As the controls, binary composites including Ti 3 C 2 T x /SiO 2 (TS), Ti 3 C 2 T x /CN (TCN) and SiO 2 /CN (SCN) were also studied. For each kind of material, the composition, structure, morphology, and application performance in the enzymatic CO 2 conversion were characterized and influencing factors were investigated. Among these composites, TSCN exhibited the best application performance and the enzyme reaction was accelerated up to 23.9 times that of the blank system. The value could reach as high as 35.3 after polyethyleneimine (PEI) modification. Following that, PEI modified composites were used as carrier of formate dehydrogenase (FDH) and apparent specific activity was up to 2.8 times that of free enzyme, which could retain 88.2% of the initial value after 10 cycles associated with the structural integrity. This work provides new impetus to CO 2 capture and conversion in a clean and mild way that shows bright application prospects.
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