TU-GOF Composite Membrane, Cross Section Morphology and Gas Permeability
Recently, the Key Laboratory of Low Carbon Conversion Science and Engineering of the Chinese Academy of Sciences and the Shanghai Advanced Research Institute of the Chinese Academy of Sciences and the Shanghai University of Science and Technology Low Carbon Energy Joint Laboratory have made progress in the self-assembly of graphene oxide frame composite membranes for small gas molecular sieve research.
The two-dimensional interlayer nanochannels formed by monolayer Graphene Oxide (GO) stacks can be used for size screening. Due to the availability of materials, simple preparation and superior performance, GO base films have rapidly become the frontier of current membrane science and technology. An important and hot topic, the separation of objects covers areas such as gas, liquids, and desalination. With the deepening of research, GO base film highlights two main issues, one is how to accurately regulate the size of two-dimensional channels to adapt to different objects (especially small Separation of molecules) The second is how to effectively enhance the force and strength between layers and increase the availability of membranes.
The GO base film and the molecular sieve film have different internal strong interactions. The main phase of the GO film is mainly weak pi-pi bonds and hydrogen bonds. The mechanical strength of the film is low, and the guest molecules can easily expand the distance between layers, which affects the separation. Separation performance and stability. The most direct and effective way to enhance the interaction force between carbon layers is to use GO oxygen containing groups as 'anchors' to covalently bridge GO carbon layers through crosslinked molecules to form uniform layer spacing. Graphene Oxide Frames (GOFs). In order to achieve the goal of small molecule screening at the same time, the cross-linked molecules must have multiple active groups, and the smaller the size, the more conducive to layer spacing control.
In this study, the researcher Sun Yuhan and Zengfeng team selected thiourea (TU) with cross-linking molecules that have double NH2- and C=S-multi-activity terminals, a molecular skeleton of only 3 atoms, and weak reducibility. In order to obtain a homogeneous and continuous GOF composite membrane, the team first reacted with GO by grafting active groups on the surface of the carrier to immobilize a single layer of GO on the carrier; then by dehydration condensation and nucleophilic addition reaction of TU, GO, in the carrier On the periodic assembly to form a homogeneous TU-GOF composite film, the first layer to achieve self-assembly. Through the condition control, TU-GOF film layer spacing can be precisely controlled, the film thickness can be controlled in tens of nanometers. Characterization results confirmed that TU The immobilization of the carbon layer greatly inhibits the swelling and deformation of the membrane in the separation medium and significantly enhances the mechanical stability of the membrane. The separation results indicate that the TU-GOF membrane is highly selective for H2, such as H2/CO2, H2/ The ideal selectivity for N2 and H2/CH4 is ~200, and the H2 permeation rate is 10-7 mol/m2/s/Pa. This is the first time that the GO base membrane is based on two-dimensional inter-layer screening for efficient separation of H2, and the performance is much higher than that of polymerization. The Robeson upper limit of the film is also superior to most inorganic films.
Relevant research results were published in "Advanced Materials." This research was supported by the National Natural Science Foundation of China, the Youth Innovation Promotion Association of the Chinese Academy of Sciences and the National Specialized Research and Development Program Nano Special Project.
