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- ItemControllable sliding transfer of wafer‐size graphene(Hoboken, NJ : Wiley, 2016) Lu, Wenjing; Zeng, Mengqi; Li, Xuesong; Wang, Jiao; Tan, Lifang; Shao, Miaomiao; Han, Jiangli; Wang, Sheng; Yue, Shuanglin; Zhang, Tao; Hu, Xuebo; Mendes, Rafael G.; Rümmeli, Mark H.; Peng, Lianmao; Liu, Zhongfan; Fu, LeiThe innovative design of sliding transfer based on a liquid substrate can succinctly transfer high‐quality, wafer‐size, and contamination‐free graphene within a few seconds. Moreover, it can be extended to transfer other 2D materials. The efficient sliding transfer approach can obtain high‐quality and large‐area graphene for fundamental research and industrial applications.
- ItemTwinned growth behaviour of two-dimensional materials(London : Nature Publishing Group, 2016) Zhang, Tao; Jiang, Bei; Xu, Zhen; Mendes, Rafael G.; Xiao, Yao; Chen, Linfeng; Fang, Liwen; Gemming, Thomas; Chen, Shengli; Rümmeli, Mark H.; Fu, LeiTwinned growth behaviour in the rapidly emerging area of two-dimensional nanomaterials still remains unexplored although it could be exploited to fabricate heterostructure and superlattice materials. Here we demonstrate how one can utilize the twinned growth relationship between two two-dimensional materials to construct vertically stacked heterostructures. As a demonstration, we achieve 100% overlap of the two transition metal dichalcogenide layers constituting a ReS2/WS2 vertical heterostructure. Moreover, the crystal size of the stacked structure is an order of magnitude larger than previous reports. Such twinned transition metal dichalcogenides vertical heterostructures exhibit great potential for use in optical, electronic and catalytic applications. The simplicity of the twinned growth can be utilized to expand the fabrication of other heterostructures or two-dimensional material superlattice and this strategy can be considered as an enabling technology for research in the emerging field of two-dimensional van der Waals heterostructures.
- ItemSynthesis of Doped Porous 3D Graphene Structures by Chemical Vapor Deposition and Its Applications(Weinheim : Wiley-VCH, 2019) Ullah, Sami; Hasan, Maria; Ta, Huy Q.; Zhao, Liang; Shi, Qitao; Fu, Lei; Choi, Jinho; Yang, Ruizhi; Liu, Zhongfan; Rümmeli, Mark H.Graphene doping principally commenced to compensate for its inert nature and create an appropriate bandgap. Doping of 3D graphene has emerged as a topic of interest because of attempts to combine its large available surface area—arising from its interconnected porous architecture—with superior catalytic, structural, chemical, and biocompatible characteristics that can be induced by doping. In light of the latest developments, this review provides an overview of the scalable chemical vapor deposition (CVD)-based growth of doped 3D graphene materials as well as their applications in various contexts, such as in devices used for energy generation and gas storage and biosensors. In particular, single- and multielement doping of 3D graphene by various dopants (such as nitrogen (N), boron (B), sulfur (S) and phosphorous (P)), the doping configurations of the resultant materials, an overview of recent developments in the field of CVD, and the influence of various parameters of CVD on graphene doping and 3D morphologies are focused in this paper. Finally, this report concludes the discussion by mentioning the existing challenges and future opportunities of these developing graphitic materials, intending to inspire the unveiling of more exciting functionalized 3D graphene morphologies and their potential properties, which can hopefully realize many possible applications. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemIn Situ N-Doped Graphene and Mo Nanoribbon Formation from Mo2Ti2C3 MXene Monolayers(Weinheim : Wiley-VCH, 2020) Mendes, Rafael Gregorio; Ta, Huy Quang; Yang, Xiaoqin; Li, Wei; Bachmatiuk, Alicja; Choi, Jin-Ho; Gemming, Thomas; Anasori, Babak; Lijun, Liu; Fu, Lei; Liu, Zhongfan; Rümmeli, Mark HermannSince the advent of monolayered 2D transition metal carbide and nitrides (MXenes) in 2011, the number of different monolayer systems and the study thereof have been on the rise. Mo2Ti2C3 is one of the least studied MXenes and new insights to this material are of value to the field. Here, the stability of Mo2Ti2C3 under electron irradiation is investigated. A transmission electron microscope (TEM) is used to study the structural and elemental changes in situ. It is found that Mo2Ti2C3 is reasonably stable for the first 2 min of irradiation. However, structural changes occur thereafter, which trigger increasingly rapid and significant rearrangement. This results in the formation of pores and two new nanomaterials, namely, N-doped graphene membranes and Mo nanoribbons. The study provides insight into the stability of Mo2Ti2C3 monolayers against electron irradiation, which will allow for reliable future study of the material using TEM. Furthermore, these findings will facilitate further research in the rapidly growing field of electron beam driven chemistry and engineering of nanomaterials. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemHigh-mobility graphene on liquid p-block elements by ultra-low-loss CVD growth(London : Nature Publishing Group, 2013) Wang, Jiao; Zeng, Mengqi; Tan, Lifang; Dai, Boya; Deng, Yuan; Rümmeli, Mark; Xu, Haitao; Li, Zishen; Wang, Sheng; Peng, Lianmao; Eckert, Jürgen; Fu, LeiThe high-quality and low-cost of the graphene preparation method decide whether graphene is put into the applications finally. Enormous efforts have been devoted to understand and optimize the CVD process of graphene over various d-block transition metals (e.g. Cu, Ni and Pt). Here we report the growth of uniform high-quality single-layer, single-crystalline graphene flakes and their continuous films over p-block elements (e.g. Ga) liquid films using ambient-pressure chemical vapor deposition. The graphene shows high crystalline quality with electron mobility reaching levels as high as 7400 cm2 V−1s−1 under ambient conditions. Our employed growth strategy is ultra-low-loss. Only trace amounts of Ga are consumed in the production and transfer of the graphene and expensive film deposition or vacuum systems are not needed. We believe that our research will open up new territory in the field of graphene growth and thus promote its practical application.
- ItemCVD growth of large area smooth-edged graphene nanomesh by nanosphere lithography(London : Nature Publishing Group, 2013) Wang, Min; Fu, Lei; Gan, Lin; Zhang, Chaohua; Rümmeli, Mark; Bachmatiuk, Alicja; Fang, Ying; Liu, ZhongfanCurrent etching routes to process large graphene sheets into nanoscale graphene so as to open up a bandgap tend to produce structures with rough and disordered edges. This leads to detrimental electron scattering and reduces carrier mobility. In this work, we present a novel yet simple direct-growth strategy to yield graphene nanomesh (GNM) on a patterned Cu foil via nanosphere lithography. Raman spectroscopy and TEM characterizations show that the as-grown GNM has significantly smoother edges than post-growth etched GNM. More importantly, the transistors based on as-grown GNM with neck widths of 65-75 nm have a near 3-fold higher mobility than those derived from etched GNM with the similar neck widths.