Recent developments in polymeric nano-based separation membranes

Polymeric nanomaterials,which have tuneable chemical structures,versatile functionalities,and good compatibility with polymeric matrices,have attracted increasing interest from researchers for the construction of polymeric nano-based separation membranes.With their distinctive nanofeatures,polymeric nano-based membranes show great promise in overcoming bottlenecks in polymer membranes,namely,the trade-off between permeability and selectivity,low stability,and fouling issues.Accordingly,recent studies have focused on tuning the structures and tailoring the surface properties of polymeric nano-based membranes via exploitation of membrane fabrication techniques and surface modification strategies,with the objective of pushing the performance of polymeric nano-based membranes to a new level.In this review,first,the approaches for fabricating polymeric nano-based mixed matrix membranes and homogeneous membranes are summarized,such as surface coating,phase inversion,interfacial polymerization,and self-assembly methods.Next,the manipulation strategies of membrane surface properties,namely,the hydrophilicity/hydrophobicity,charge characteristics,and surface roughness,and interior microstructural properties,namely,the pore size and content,channel construction and regulation,are comprehensively discussed.Subsequently,the separation performances of liquid ions/molecules and gas molecules through polymeric nano-based membranes are systematically reported.Finally,we conclude this review with an overview of various unsolved scientific and technical challenges that are associated with new opportunities in the development of advanced polymeric nano-based membranes.

Highly active iridium catalyst for hydrogen production from formic acid

Formic acid（FA） dehydrogenation has attracted a lot of attentions since it is a convenient method for H_2 production. In this work, we designed a self-supporting fuel cell system, in which H_2 from FA is supplied into the fuel cell, and the exhaust heat from the fuel cell supported the FA dehydrogenation. In order to realize the system, we synthesized a highly active and selective homogeneous catalyst Ir Cp＊Cl_2 bpym for FA dehydrogenation. The turnover frequency（TOF） of the catalyst for FA dehydrogenation is as high as7150 h^（-1）at 50°C, and is up to 144,000 h^（-1）at 90°C. The catalyst also shows excellent catalytic stability for FA dehydrogenation after several cycles of test. The conversion ratio of FA can achieve 93.2%, and no carbon monoxide is detected in the evolved gas. Therefore, the evolved gas could be applied in the proton exchange membrane fuel cell（PEMFC） directly. This is a potential technology for hydrogen storage and generation. The power density of the PEMFC driven by the evolved gas could approximate to that using pure hydrogen.