Shijun Nie,Juan Wu,Lan Wang,Fan Cheng,Zhengguang Sun,Xiaobo Chen,Hai Liu,Sheng Wen,Chunli Gong
The trade-off between ionic conductivity and mechanical properties is the key issue facing anion exchange membranes (AEMs) at present. Herein, a new strategy combing three-dimensional (3D) hierarchical nanoarchitecture and magnetic field orientation was proposed to prepare imidazolium-functionalized poly(2,6-dimethyl phenylene oxide) (ImPPO)-based composite AEMs with simultaneously improved ionic conductivity and mechanical strength. Magnetic Fe 3 O 4 @LDH microspheres using Fe 3 O 4 as the core and two-dimensional lamellar anion conductor, layered double hydroxide (LDH), as the shell were prepared through a simple co-precipitation method. The as-prepared Fe 3 O 4 @LDH was then incorporated into ImPPO matrix and induced by an external magnetic field to fabricate Fe 3 O 4 @LDH-orientated composite AEMs. The hierarchical-structured Fe 3 O 4 @LDH can not only effectively avoid the stacking of LDH laminates and thus fully play the ion conduction ability of LDH, but also contribute to the formation of continuous OH − ion transport pathway in the composite system after magnetic field induction. The magnetic-field-oriented membrane with 1% Fe 3 O 4 @LDH doping exhibited ionic conductivity of 128.9 mS cm −1 at 80 °C, which was 43.1% higher than that of pure ImPPO. Moreover, the high dry strength (30.7 MPa) and satisfactory wet strength and flexibility of the composite membrane were also obtained. The assembled direct methanol fuel cell demonstrated a peak power density of 11.7 mW cm −2 , and showed an OCV retention of as high as 94.7% after continuous operation for 100 h, indicating their great potential for fuel cell applications.
Liu Xin,Xie Na,Xue Jiandang,Li Mengyuan,Zheng Chenyang,Zhang Junfeng,Qin Yanzhou,Yin Yan,Dekel Dario R.,Guiver Michael D.
Through-plane (TP) conducting pathways in anion-exchange membranes (AEMs) are desirable for AEM fuel cells as they serve as short and efficient routes for hydroxide ion transport between electrodes, improving power output. Electric and magnetic fields have previously been used to create TP-oriented structures in AEMs, but with modest performance gains. Here we use paramagnetic ferrocenium polymers to prepare TP-oriented AEMs under a magnetic field. The magnetic field induces a mixed-valence state, which effectuates higher anion dissociation and enhanced alkali/redox stability. Our AEMs display a promising TP hydroxide conductivity of ~160 mS cm −1 at 95 °C in water, and no appreciable hydroxide conductivity loss over 4,320 h at 95 °C in alkali. The assembled fuel cells achieve a power output of 737 mW cm −2 at 80 °C and 80% relative humidity, and a durability of 3.9% voltage loss and 2.2% high-frequency resistance increase over 500 h at 500 mA cm −2 , 120 °C and 40% relative humidity.
Despite the fact that human neural cell models have played significant roles in both research and cell replacement therapies for neurological diseases, the existing techniques for obtaining neurons from human pluripotent stem cells (hPSCs) are arduous and intricate. Additionally, the evaluation of neuron quality in the natural environment remains deficient. Consequently, we have developed a comprehensive platform utilizing magnetic-field-directed self-assembly (MDSA) of MXenes@Fe3O4 (M/F) nanocomposites. This platform facilitates the cultivation and in situ analysis of differentiated dopaminergic (DA) neurons. Our results showed that the introduction of M/F enhances neurite outgrowth and leads to the development of more intricate ramifications. Moreover, with the increase of magnetic field intensity, neurite outgrowth is further enhanced, and the proportion of differentiated mature neurons from hPSCs increases. This suggests that our platform promotes the maturation of neurons, emphasizing the crucial role of biophysical cues in expediting the differentiation process. The homogenization platform formed by MDSA of M/F nanocomposites exhibits high conductivity, leading to its exceptional performance in the real-time monitoring of the release of dopamine neurotransmitter from hPSC-derived DA neurons. Hence, this platform demonstrates significant potential for monitoring cell quality. In conclusion, our integrated platform, based on MDSA of M/F nanocomposites, offers a reliable and efficient means for the in vitro generation of human neurons with a controllable quality. The as-prepared platform holds potential for enhancing neuronal maturation and ensuring consistent cell quality, showing significant implications for in vitro biological research, disease modeling, and cell replacement therapy.
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