文献类型：期刊文献

英文题名：Novel 2D CaCl crystals with metallicity, room-temperature ferromagnetism, heterojunction, piezoelectricity-like property and monovalent calcium ions

作者：Zhang, Lei[1];Shi, Guosheng[2,3];Peng, Bingquan[1,4];Gao, Pengfei[1];Chen, Liang[5];Zhong, Ni[6];Mu, Liuhua[4];Zhang, Lijuan[4,7];Zhang, Peng[1];Gou, Lu[1];Zhao, Yimin[1];Liang, Shanshan[4];Jiang, Jie[4];Zhang, Zejun[4];Ren, Hongtao[1];Lei, Xiaoling[3,4,7];Yi, Ruobing[1,2];Qiu, Yinwei[5];Zhang, Yufeng[8];Liu, Xing[2];Wu, Minghong[2];Yan, Long[4];Duan, Chungang[6];Zhang, Shengli[1];Fang, Haiping[3,4,7]

机构：[1]Xi An Jiao Tong Univ, Sch Phys, MOE Key Lab Nonequilibrium Synth & Modulat Conden, Xian 710049, Peoples R China;[2]Shanghai Univ, Shanghai Appl Radiat Inst, Shanghai 200444, Peoples R China;[3]East China Univ Sci & Technol, Dept Phys, Shanghai 200237, Peoples R China;[4]Chinese Acad Sci, Shanghai Inst Appl Phys, Shanghai 201800, Peoples R China;[5]Zhejiang A&F Univ, Dept Opt Engn, Hangzhou 311300, Peoples R China;[6]East China Normal Univ, Key Lab Polar Mat & Devices, Minist Educ, Shanghai 200241, Peoples R China;[7]Chinese Acad Sci, Shanghai Adv Res Inst, Zhangjiang Lab, Shanghai 201210, Peoples R China;[8]Xiamen Univ, Coll Phys Sci & Technol, Xiamen 361005, Peoples R China

年份：2021

卷号：8

期号：7

外文期刊名：NATIONAL SCIENCE REVIEW

收录：;EI(收录号：20213310772941);WOS:【SCI-EXPANDED(收录号:WOS:000697170300014)】；

基金：This work was supported by the National Natural Science Foundation of China (11774279, 11974366, 11675246, 11774280 and U1932123), the National Science Fund for Outstanding Young Scholars (11722548 and 11922410), the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (QYZDJ-SSW-SLH053), the Key Research Program of the Chinese Academy of Sciences (KJZD-EW-M03), Shanghai Supercomputer Center of China and the Special Program for Applied Research on SuperComputation of the NSFC-Guangdong Joint Fund (the second phase), the Fundamental Research Funds for the Central Universities, the World-Class Universities (Disciplines) and the Characteristic Development Guidance Funds for the Central Universities, and Young Talent Support Plan of Xi'an Jiaotong University.

语种：英文

外文关键词：2D CaCl crystals; monovalent calcium ions; room-temperature ferromagnetism; heterojunction; coexistence of piezoelectricity-like property and metallicity

摘要：Under ambient conditions, the only known valence state of calcium ions is +2, and the corresponding crystals with calcium ions are insulating and nonferromagnetic. Here, using cryo-electron microscopy, we report direct observation of two-dimensional (2D) CaCl crystals on reduced graphene oxide (rGO) membranes, in which the calcium ions are only monovalent (i.e. +1). Remarkably, metallic rather than insulating properties are displayed by those CaCl crystals. More interestingly, room-temperature ferromagnetism, graphene-CaCl heterojunction, coexistence of piezoelectricity-like property and metallicity, as well as the distinct hydrogen storage and release capability of the CaCl crystals in rGO membranes are experimentally demonstrated. We note that such CaCl crystals are obtained by simply incubating rGO membranes in salt solutions below the saturated concentration, under ambient conditions. Theoretical studies suggest that the formation of those abnormal crystals is attributed to the strong cation- interactions of the Ca cations with the aromatic rings in the graphene surfaces. The findings highlight the realistic potential applications of such abnormal CaCl material with unusual electronic properties in designing novel transistors and magnetic devices, hydrogen storage, catalyzers, high-performance conducting electrodes and sensors, with a size down to atomic scale.