Yan Wang,Xiaoyue Fu,Yuxiu He,Xiyuan Li,Yingjie Feng
Anion exchange membrane water electrolysis (AEMWE) is a promising hydrogen production technology for clean energy storage and conversion applications. However, in practical applications, AEMWE still face various challenges, such as slow reaction kinetics and a poor durability. This study simultaneously performed chronopotentiometry for 672 h in a half-cell (200 mA cm −2 ) and 170 h in a single-cell (500 mA cm −2 ) to comprehensively evaluate the durability of a NiFe-LDH/NF electrode prepared via the hydrothermal deposition of a NiFe-layered double hydroxide (NiFe-LDH) on nickel felt (NF). The half-cell test results showed that after 672 h, the voltage degradation was only 2 mV compared to the initial voltage (1 h). The single-cell test results showed that below 30 h, the cell underwent an activation–stabilisation process, while after 170 h, the voltage degradation was only 45 mV compared to that at 30 h. In situ electrochemical Raman spectroscopy revealed that the formation of Ni(Fe)OOH at high potentials enhanced the oxygen evolution reaction activity of the NiFe-LDH/NF electrode. Meanwhile, TEM and SEM morphological observations showed that the three-dimensional flower-like cluster structure formed by the NiFe-LDH sheets was responsible for the high durability of the NiFe-LDH/NF electrode in both half-cell and single-cell tests.
Yongyue Zhang,Lei Wang,Lin Li,Hua Wang,Xinyu Dong,Yanqiu Pan,Tonghua Wang
In this work, polyacrylonitrile (PAN) based organic solvent nanofiltration (OSN) membranes were prepared by combining nonsolvent-induced phase separation (NIPS) and thermal crosslinking methods. The structure and morphology changes of the PAN membrane during thermal crosslinking were investigated by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrometer (XPS), X-ray diffractometer (XRD) and scanning electron microscope (SEM). The thermal crosslinking reaction of PAN chains and fusion of pore structure occurred simultaneously, which were conducive to the transformation of an asymmetric PAN ultrafiltration (UF) membrane into OSN membrane. The influences of thermal crosslinking temperature and time on the structure evolutions and nanofiltration performance of PAN based crosslinked membranes were systematically investigated. The formation mechanisms of OSN membrane were discussed in terms of the evolutions of chemical structure and pore structure. The resultant thermally crosslinked membranes showed excellent thermal stability and solvent resistance in different organic solvents. Furthermore, a remarkable stability of OSN performances in long-term test was exhibited due to the formation of crosslinked ladder structure of PAN. This work showed that thermal crosslinking is an encouraging and promising method to transform UF membranes into OSN membranes.
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