Membrane-based separation technology has attracted great interest in many separation fields due to its advantages of easy-operation, energy-efficiency, easy scale-up, and environmental friendliness. The development of novel membrane materials and membrane structures is an urgent demand to promote membrane-based separation technology. Graphene oxide (GO), as an emerging star nano-building material, has showed great potential in the membrane-based separation field. In this review paper, the latest research progress in GO-based membranes focused on adjusting membrane structure and enhancing their mechanical strength as well as structural stability in aqueous environment is highlighted and discussed in detail. First, we briefly reviewed the preparation and characterization of GO. Then, the preparation method, characterization, and type of GO-based membrane are summarized. Finally, the advancements of GO-based membrane in adjusting membrane structure and enhancing their mechanical strength, as well as structural stability in aqueous environment, are particularly discussed. This review hopefully provides a new avenue for the innovative developments of GO-based membrane in various membrane applications.
Hierarchically structured bimetallic NiCo‐MOF/LDH/Ni foam (NiCo‐MOF/LDH/NF; MOF=metal−organic framework, LDH=layered double hydroxides) composites were successfully fabricated by means of the in situ growth of NiCo‐MOF on the NiCo LDH buffer‐layer‐modified NF surface. After carbonization, the derived NiCo alloy@C/NixCo1‐xO/NF hierarchical nanocomposite showed excellent electrocatalytic activity with respect to the oxygen evolution reaction (OER); specifically, it exhibited a very low overpotential of 300 mV at a current density of 100 mA cm−2. The outstanding OER activity of the composite may be attributed to the open structure of the nanocomposite, the formation of the highly dispersed CoNi alloy, and the synergistic interaction between CoNi@C and NixCo1‐xO. This work introduces a new strategy for constructing advanced hierarchically structured nanocomposites for diverse applications.
Summary
Selective CO methanation (CO‐SMET) is viewed as an effective H2‐rich gas purification technique for proton exchange membrane fuel cells. In this work, improved composite‐supported Ru catalysts were developed for the CO‐SMET process. Mixed metal oxides (MMOs) obtained by calcination of layered double hydroxides precursor were used as an effective catalyst supports. After incorporation of TiO2, the resulting TiO2‐MMO composites were expected to have an enhanced catalytic performance. Therefore, a series of TiO2‐NiAl layered double hydroxides was successfully prepared via 1‐pot deposition method. After calcination, the derived TiO2‐NiAl MMO‐supported Ru catalysts obtained by impregnation method showed excellent catalytic performance for CO‐SMET reaction. The catalyst could deeply remove the CO outlet concentration (<10 ppm) with a high selectivity (>50%) over the wide low‐temperature window (175‐260°C). Furthermore, the catalyst also showed high stability with no deactivation during a long‐term durability test (120 h). Based on X‐ray diffraction, Fourier transform infrared, Raman, thermogravimetric differential scanning calorimetry, N2 adsorption‐desorption, temperature‐programmed reduction, scanning electron microscopy, and transmission electron microscopy analyses, the enhanced catalytic performance of the TiO2‐NiAl MMO‐supported Ru catalyst was found to be related to the higher dispersion of Ru nanoparticles, partially reduced NiO species, and the increased specific surface area and structural stability of the support. The facile synthesis strategy proposed herein may open a new window for the efficient production of high‐quality H2.
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