Single atoms are the ultimate minimum size limit for catalysts. Graphene, as an exciting, ultimately thin （one atom thick） material can be imaged in a transmission electron microscope with relatively few imaging art...Single atoms are the ultimate minimum size limit for catalysts. Graphene, as an exciting, ultimately thin （one atom thick） material can be imaged in a transmission electron microscope with relatively few imaging artefacts. Here, we directly observe the behavior of single Cr atoms in graphene mono- and di-vacancies and, more importantly, at graphene edges. Similar studies at graphene edges with other elemental atoms, with the exception of Fe, show catalytic etching of graphene. Fe atoms have been shown to both etch and grow graphene. In contrast, Cr atoms are only observed to induce graphene growth. Complementary theoretical calculations illuminate the differences between Fe and Cr, and confirm single Cr atoms as superior catalysts for sp^2 carbon growth.展开更多
Nitrogen-doped（N-doped） graphene has attracted increasing attentions because of the significantly enhanced properties in physic, chemistry, biology and material science, as compared with those of pristine graphene. ...Nitrogen-doped（N-doped） graphene has attracted increasing attentions because of the significantly enhanced properties in physic, chemistry, biology and material science, as compared with those of pristine graphene. By date, N-doped graphene has opened up an exciting new field in the science and technology of two-dimensional materials. From the viewpoints of chemistry and materials, this article presents an overview on the recent progress of N-doped graphene, including the typical synthesis methods, characterization techniques, and various applications in energy fields. The challenges and perspective of Ndoped graphene are also discussed. We expect that this review will provide new insights into the further development and practical applications of N-doped graphene.展开更多
The two-dimensional material graphene shows its extraordinary potential in many application fields.As the most effective method to synthesize large-area monolayer graphene, chemical vapor deposition has been well deve...The two-dimensional material graphene shows its extraordinary potential in many application fields.As the most effective method to synthesize large-area monolayer graphene, chemical vapor deposition has been well developed; however, it still faces the challenge of a high occurrence of multilayer graphene, which causes the small effective area of monolayer graphene. This phenomenon limits its applications in which only a big size of monolayer graphene is needed. In this paper, by introducing a redistribution stage after the decomposition of carbon source gas to redistribute the carbon atoms dissolved in Pt foils, the number of multilayer flakes on the monolayer graphene decreases. The mean area of monolayer graphene can be extended to about 16 000μ m^2, which is eight times larger than that of the graphene grown without the redistribution stage. A Raman spectrograph is used to demonstrate the high quality of the monolayer graphene grown by the improved process.展开更多
基金The following are gratefully acknowledged. The National Natural Science Foundation of China （No. 51672181）, the National Science Center for the financial support within the frame of the Sonata Program （No. 2014/13/D/ST5/02853） and the Opus program （No. 2015/19/B/ST5/03399）.
文摘Single atoms are the ultimate minimum size limit for catalysts. Graphene, as an exciting, ultimately thin （one atom thick） material can be imaged in a transmission electron microscope with relatively few imaging artefacts. Here, we directly observe the behavior of single Cr atoms in graphene mono- and di-vacancies and, more importantly, at graphene edges. Similar studies at graphene edges with other elemental atoms, with the exception of Fe, show catalytic etching of graphene. Fe atoms have been shown to both etch and grow graphene. In contrast, Cr atoms are only observed to induce graphene growth. Complementary theoretical calculations illuminate the differences between Fe and Cr, and confirm single Cr atoms as superior catalysts for sp^2 carbon growth.
基金supported by the National Key R&D Program of China(2017YFA0208200,2016YFB0700600,2015CB659300)Projects of NSFC(21403105,21573108)+2 种基金Anhui Provincial Key Research and Development Program(1704A0902022)Natural Science Foundation of Jiangsu Province(BK20150583,BK20160647)the Fundamental Research Funds for the Central Universities(020514380107)
文摘Nitrogen-doped（N-doped） graphene has attracted increasing attentions because of the significantly enhanced properties in physic, chemistry, biology and material science, as compared with those of pristine graphene. By date, N-doped graphene has opened up an exciting new field in the science and technology of two-dimensional materials. From the viewpoints of chemistry and materials, this article presents an overview on the recent progress of N-doped graphene, including the typical synthesis methods, characterization techniques, and various applications in energy fields. The challenges and perspective of Ndoped graphene are also discussed. We expect that this review will provide new insights into the further development and practical applications of N-doped graphene.
基金Project supported by the National Natural Science Foundation of China(No.61377106)
文摘The two-dimensional material graphene shows its extraordinary potential in many application fields.As the most effective method to synthesize large-area monolayer graphene, chemical vapor deposition has been well developed; however, it still faces the challenge of a high occurrence of multilayer graphene, which causes the small effective area of monolayer graphene. This phenomenon limits its applications in which only a big size of monolayer graphene is needed. In this paper, by introducing a redistribution stage after the decomposition of carbon source gas to redistribute the carbon atoms dissolved in Pt foils, the number of multilayer flakes on the monolayer graphene decreases. The mean area of monolayer graphene can be extended to about 16 000μ m^2, which is eight times larger than that of the graphene grown without the redistribution stage. A Raman spectrograph is used to demonstrate the high quality of the monolayer graphene grown by the improved process.
