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The porous polyimide (PI) composite fibers, which exhibit high-efficiency electromagnetic wave adsorption (EMWA) performance, were successfully fabricated by controlling temperature of the coagulation bath during the wet spinning process. The mechanical properties of composite fiber decreased and average radius of micropores increased gradually with the rise of coagulation bath temperature. In addition, carbon nanotubes (CNTs) and nano-[Fe.sub.3][O.sub.4] were introduced into the system by in situ polymerization. CNTs and nano-[Fe.sub.3][O.sub.4] contribute to the attenuation of electromagnetic wave (EMW) through microwave absorption and reflection loss (RL), and the porous structure was able to provide multiple reflection paths for incident EMW and achieved higher attenuation. Particularly, when the temperature of coagulation bath was 50[degrees]C, the minimum RL ([RL.sub.min]) value of the PI/CNTs/nano-[Fe.sub.3][O.sub.4] (PI/C-Fe) composite fibers was demonstrated to be -54.61 dB with the matching thickness of 2.10 mm. The successful preparation of PI/C-Fe composite fiber in this study pointed out a new direction for the application of Pi-based fiber materials in structural EMWA materials. KEYWORDS composite materials, fiber technology, porous materials, 1 | INTRODUCTION With the rapid development of modern communication technology, electromagnetic radiation and electromagnetic interference are becoming everywhere. As a new form of pollution, they have brought adverse effects [...]

Designing highly active oxygen reduction reaction (ORR) catalysts is crucial to boost the fuel cell economy. Previous research has mainly focused on Pt-based alloy catalysts in which surface Pt is the solely active site and the activity improvement was challenged by the discovered scaling relationship. Herein we report a new concept of utilizing dual active sites for the ORR and demonstrate its effectiveness by synthesizing a SnO x/Pt-Cu-Ni heterojunctioned catalyst. A maximum of 40% enhancement in the apparent specific activity, which corresponds to 10-fold enhancement on interface sites, is measured compared with pure Pt-Cu-Ni. Detailed investigations suggest an altered dual-site cascade mechanism wherein the first two steps occur on SnO x sites and the remaining steps occur on adjacent Pt sites, allowing a significant decrease in the energy barrier. This study with the suggested dual-site cascade mechanism shows the potential to overcome the ORR energy barrier bottleneck to develop highly active catalysts.

Designing highly active oxygen reduction reaction (ORR) catalysts is crucial to boost the fuel cell economy. Previous research has mainly focused on Pt-based alloy catalysts in which surface Pt is the solely active site and the activity improvement was challenged by the discovered scaling relationship. Herein we report a new concept of utilizing dual active sites for the ORR and demonstrate its effectiveness by synthesizing a SnO x/Pt-Cu-Ni heterojunctioned catalyst. A maximum of 40% enhancement in the apparent specific activity, which corresponds to 10-fold enhancement on interface sites, is measured compared with pure Pt-Cu-Ni. Detailed investigations suggest an altered dual-site cascade mechanism wherein the first two steps occur on SnO x sites and the remaining steps occur on adjacent Pt sites, allowing a significant decrease in the energy barrier. This study with the suggested dual-site cascade mechanism shows the potential to overcome the ORR energy barrier bottleneck to develop highly active catalysts.

The electrocatalytic dehydrogenation of ethylamine (EDH), owing to its high hydrogen content, holds broad prospects in electrochemical hydrogen (H2) production, H2 storage, and addressing energy issues, thus deserving wide attention. In this feature article, we first summarized the fundamentals of thermocatalytic and electrocatalytic EDH and reviewed the recent state-of-the-art advances in catalyst research, specifically platinum group metal (PGM) catalysts and non-PGM catalysts. We systematically discussed the potential applications of electrocatalytic EDH in energy storage and conversion. Finally, we provide our perspective on the key challenges and future developments in this field. We believe this feature article will offer helpful guidance for oriented design and optimization of stable and efficient catalysts for electrocatalytic EDH and related energy applications. [ABSTRACT FROM AUTHOR]

The polyimide (PI)/carbon nanotube (CNT) films including 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), p-phenylenediamine (p-PDA), and CNTs were prepared, which have prominent electromagnetic (EM) wave absorption performance. Experimental analyses of the mechanical properties, thermal stabilities, coefficient of thermal expansion (CTE), the glass transition temperature ([T.sub.g]), and EM parameter revealed the beneficial effects of the CNTs on the resulting composite films. In particular, when the content of CNTs is 6 wt%, the film shows the highest EM wave absorption performance, which exhibits the effective absorption bandwidth of 2.72 GHz with the matching thickness of only 2.0 mm. These results indicate that PI-based films have a certain potential application in the area of EM wave-absorbing materials. KEYWORDS carbon nanotubes, electromagnetic wave-absorbing materials, polyimide film, 1 | INTRODUCTION Various electronic and electrical equipment types play a vital role in people's everyday life and social construction. [1-4] However, the EM radiation and interference have gradually affected [...]