| 1. |
Wang, Weijun; Meng, You; Zhang, Yuxuan; Zhang, Zhuomin; Wang, Wei; Lai, Zhengxun; Xie, Pengshan; Li, Dengji; Chen, Dong; Quan, Quan; Yin, Di; Liu, Chuntai; Yang, Zhengbao; Yip, SenPo; Ho, Johnny C., Electrically Switchable Polarization in Bi2O2Se Ferroelectric Semiconductors, ADVANCED MATERIALS, 10.1002/adma.202210854, 2023.02, Atomically 2D layered ferroelectric semiconductors, in which the polarization switching process occurs within the channel material itself, offer a new material platform that can drive electronic components toward structural simplification and high-density integration. Here, a room-temperature 2D layered ferroelectric semiconductor, bismuth oxychalcogenides (Bi2O2Se), is investigated with a thickness down to 7.3 nm (≈12 layers) and piezoelectric coefficient (d33) of 4.4 ±0.1 pm V−1. The random orientations and electrically dependent polarization of the dipoles in Bi2O2Se are separately uncovered owing to the structural symmetry-breaking at room temperature. Specifically, the interplay between ferroelectricity and semiconducting characteristics of Bi2O2Se is explored on device-level operation, revealing the hysteresis behavior and memory window (MW) formation. Leveraging the ferroelectric polarization originating from
Bi2O2Se, the fabricated device exhibits “smart” photoresponse tunability and excellent electronic characteristics, e.g., a high on/off current ratio > 104 and a large MW to the sweeping range of 47% at VGS = ±5 V. These results demonstrate the synergistic combination of ferroelectricity with semiconducting characteristics in Bi2O2Se, laying the foundation for integrating sensing, logic, and memory functions into a single material system that can overcome the bottlenecks in von Neumann architecture.. |
| 2. |
Chen, Dong; Zhang, Shaoce; Yin, Di; Li, Wanpeng; Bu, Xiuming; Quan, Quan; Lai, Zhengxun; Wang, Wei; Meng, You; Liu, Chuntai; Yip, SenPo; Chen, Fu-Rong; Zhi, Chunyi; Ho, Johnny C. C., Tailored p-Orbital Delocalization by Diatomic Pt-Ce Induced Interlayer Spacing Engineering for Highly-Efficient Ammonia Electrosynthesis, ADVANCED ENERGY MATERIALS, 10.1002/aenm.202203201, 13, 6, 2023.02, Electrochemical nitrate reduction to ammonia (eNO3RR) is a green and appealing method for ammonia synthesis, but is hindered by the multistep chemical reaction and competitive hydrogen generation. Herein, the synthesis of 2D SnS nanosheets with tailored interlayer spacing is reported, including both expansion and compression, through the active diatomic Pt-Ce pairs. Taking together the experimental results, in situ Raman spectra, and DFT calculations, it is found that the compressed interlayer spacing can tune the electron density of localized p-orbital in Sn into its delocalized states, thus enhancing the chemical affinity towards NO3− and NO2− but inhibiting hydrogen generation simultaneously. This phenomenon significantly facilitates the rate-determining step (*NO3→*NO2) in eNO3RR, and realizes an excellent Faradaic efficiency (94.12%) and yield rate (0.3056 mmol cm−2 h−1) for NH3 at −0.5 V versus RHE. This work provides a powerful strategy for tailoring flexible interlayer spacing of 2D materials and opens a new avenue for constructing high-performance catalysts for ammonia synthesis.. |
| 3. |
Kang X., Yip S.P., Meng Y., Wang W., Li D., Liu C., Ho J.C, High-Performance Electrically Transduced Hazardous Gas Sensors Based on Low-Dimensional Nanomaterials, Nanoscale Advances, 10.1039/d1na00433f , 3, 6254-6270, 2021.09, Low-dimensional nanomaterials have been proven as promising high-performance gas sensing components due to their fascinating structural, physical, chemical, and electronic characteristics. In particular, materials with low dimensionalities (i.e., 0D, 1D, and 2D) possess an extremely large surface area-to-volume ratio to expose abundant active sites for interactions with molecular analytes. Gas sensors based on these materials exhibit a sensitive response to subtle external perturbations on sensing channel materials via electrical transduction, demonstrating a fast response/recovery, specific selectivity, and remarkable stability. Herein, we comprehensively elaborate gas sensing performances in the field of sensitive detection of hazardous gases with diverse low-dimensional sensing materials and their hybrid combinations. We will first introduce the common configurations of gas sensing devices and underlying transduction principles. Then, the main performance parameters of gas sensing devices and subsequently the main underlying sensing mechanisms governing their detection operation process are outlined and described. Importantly, we also elaborate the compositional and structural characteristics of various low-dimensional sensing materials, exemplified by the corresponding sensing systems. Finally, our perspectives on the challenges and opportunities confronting the development and future applications of low-dimensional materials for high-performance gas sensing are also presented. The aim is to provide further insights into the material design of different nanostructures and to establish relevant design guidelines to facilitate the device performance enhancement of nanomaterial based gas sensors.. |
