Engineering topics
Zhou, Wenyang
Publications and source records attributed to Zhou, Wenyang.
Imidazole-graphyne: a new 2D carbon nitride with a direct bandgap and strong IR refraction
Six-membered rings are common building blocks of many carbon structures. Recent studies have shown that penta-graphene composed of five-membered carbon rings have properties very different from that of graphene. This has motivated the search for new carbon structures. Among this is cp-graphyne, composed of carbon pentagons and bridged by acetylenic linkers. However, the bandgap of cp-graphyne, like that of graphene, is zero, making it unsuitable for applications in electronics. Herein, we show that a new two-dimensional (2D) carbon nitride structure formed by assembling the five-membered imidazole molecules with acetylenic linker can overcome this limitation. Named ID-GY, this new material not only has a direct band gap of 1.10 eV, but it is dynamically and mechanically stable and can withstand temperatures up to 1200 K. In addition, due to its porous and anisotropic geometry, the Young's modulus of ID-GY along the diagonal direction is lower than that of most 2D materials reported previously. Equally important, ID-GY exhibits strong refraction near infrared (IR) and has potential for applications in nanoelectronics and optical devices. These results, based on density functional theory, can stimulate experimental studies.
A 3D porous honeycomb carbon as Na-ion battery anode material with high capacity, excellent rate performance, and robust stability
Motivated by the synthesis of three-dimensional (3D) honeycomb carbon structures and the subsequent theoretical prediction of an energetically more favorable hexagonal carbon phase composed of 28 carbon atoms in the unit cell (hC28) with ordered pores, excellent mechanical properties, and metallic feature, we explore its potential for a Na-ion battery (NIB) anode material. Using density functional theory based calculations, we find that hC28 is a promising candidate whose specific capacity of 717 mAh/g is almost three times larger than that of hard carbon (~250 mAh/g). In addition, migration barrier of Na ions along the honeycomb channel is only 0.08 eV and the volume change during the charging/discharging process is merely 2.30%, which are much less than those of other carbon-based NIB anode materials. The average voltage is also low (0.36 eV) which can provide high operating voltage when connected to the cathode. Finally, these encouraging results would pave the way towards the development of hC28 as NIB anode with high capacity, excellent rate performance, low open-circuit voltage, and long-term cycle life.