Magnetic separation of oxygen from air

具有高亲水性的Ti3C2Tx Mxene薄板正被考虑用于气体分离应用。在此，我们制备了不同GO浓度的MXene/氧化石墨烯(GO)复合膜，具有较小的层间距和排列的小片，以获得更好的分离性能。用不同GO组分的MXene/GO悬浮液在AAO衬底上进行真空过滤，制得膜。膜的厚度在20~100 nm之间调节，悬浮液的体积一定，FTIR、XPS光谱表明MXene血小板与GO单分子膜通过Ti-O-C共价键相互作用。此外，XPS和紫外吸收光谱表明MXene对GO片层有一定的还原作用。X-射线散射表明，MXene的d间距从11.4A增加到13.5A；在低GO含量下，这解释了GO在MXene中发生了层间插入。由于Ti-O-C共价键的作用，MXene/GO膜的稳定性和力学性能较纯MXene膜有所提高。氮气吸附测试表明，GO的加入降低了MXene膜的孔体积和气体吸收率，这归因于Ti-O-C共价键的形成和取向度的提高。由于复合膜的孔体积较小，加入GO后，膜的气体渗透率降至纯MXE值的一半。而H_2/CO_2选择性从纯MXene的115提高到MX50GO50的536，表明复合膜具有较好的筛分能力。

Ti3C2Tx MXene sheets with high hydrophilicity are being considered for gas separation applications. Herein, we prepared MXene/graphene oxide (GO) composite membranes at different GO concentrations with smaller interlayer spacing and aligned platelets for a better separation performance. The membranes were fabricated by vacuum filtration of MXene/GO suspension at different GO compositions on AAO substrate. The membranes thickness was adjusted between 20 nm to 100 nm with an exact volume of the suspension.FTIR, XPS spectra revealed the interactions between MXene platelets and GO monolayer through Ti-O-C covalent bonds. Moreover, XPS and UV absorbance indicated the reduction of GO sheets by MXene. X-ray scattering exhibited that the d-spacing of MXene increases from 11.4 A to 13.5 A; at low GO contents, which explained the interlamellar insertion of GO into MXene has occurred. The stability and mechanical properties of the MXene/GO membranes improved compared to the pure MXene due to the Ti-O-C covalent bonding. N2 adsorption measurement showed a decrease in pore volume and gas uptake of MXene membranes by the addition of GO, which was attributed to the Ti-O-C covalent bonds and improvement in the alignment degree. The gas permeance of the composite membranes decreased down to half of its pure MXene value by adding GO because of the smaller pore volume. However, the H2/CO2 selectivity significantly improved from 115 for pure MXene to 536 for MX50GO50, indicating a better sieving ability in the composite membranes.