DSpace :: Browsing by Author "Cuniberti, Gianaurelio"

Browsing by Author "Cuniberti, Gianaurelio"

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Applications of Carbon Nanotubes in the Internet of Things Era
(Berlin ; Heidelberg [u.a.] : Springer, 2021) Pang, Jinbo; Bachmatiuk, Alicja; Yang, Feng; Liu, Hong; Zhou, Weijia; Rümmeli, Mark H.; Cuniberti, Gianaurelio
The post-Moore's era has boosted the progress in carbon nanotube-based transistors. Indeed, the 5G communication and cloud computing stimulate the research in applications of carbon nanotubes in electronic devices. In this perspective, we deliver the readers with the latest trends in carbon nanotube research, including high-frequency transistors, biomedical sensors and actuators, brain-machine interfaces, and flexible logic devices and energy storages. Future opportunities are given for calling on scientists and engineers into the emerging topics.
Applications of MXenes in human-like sensors and actuators
(New York, NY [u.a.] : Springer, 2022) Pang, Jinbo; Peng, Songang; Hou, Chongyang; Wang, Xiao; Wang, Ting; Cao, Yu; Zhou, Weijia; Sun, Ding; Wang, Kai; Rümmeli, Mark H.; Cuniberti, Gianaurelio; Liu, Hong
Human beings perceive the world through the senses of sight, hearing, smell, taste, touch, space, and balance. The first five senses are prerequisites for people to live. The sensing organs upload information to the nervous systems, including the brain, for interpreting the surrounding environment. Then, the brain sends commands to muscles reflexively to react to stimuli, including light, gas, chemicals, sound, and pressure. MXene, as an emerging two-dimensional material, has been intensively adopted in the applications of various sensors and actuators. In this review, we update the sensors to mimic five primary senses and actuators for stimulating muscles, which employ MXene-based film, membrane, and composite with other functional materials. First, a brief introduction is delivered for the structure, properties, and synthesis methods of MXenes. Then, we feed the readers the recent reports on the MXene-derived image sensors as artificial retinas, gas sensors, chemical biosensors, acoustic devices, and tactile sensors for electronic skin. Besides, the actuators of MXene-based composite are introduced. Eventually, future opportunities are given to MXene research based on the requirements of artificial intelligence and humanoid robot, which may induce prospects in accompanying healthcare and biomedical engineering applications. [Figure not available: see fulltext.]
Applications of nanogenerators for biomedical engineering and healthcare systems
(Weinheim : Wiley, 2021) Wang, Wanli; Pang, Jinbo; Su, Jie; Li, Fujiang; Li, Qiang; Wang, Xiaoxiong; Wang, Jingang; Ibarlucea, Bergoi; Liu, Xiaoyan; Li, Yufen; Zhou, Weijia; Wang, Kai; Han, Qingfang; Liu, Lei; Zang, Ruohan; Rümmeli, Mark H.; Li, Yang; Liu, Hong; Hu, Han; Cuniberti, Gianaurelio
The dream of human beings for long living has stimulated the rapid development of biomedical and healthcare equipment. However, conventional biomedical and healthcare devices have shortcomings such as short service life, large equipment size, and high potential safety hazards. Indeed, the power supply for conventional implantable device remains predominantly batteries. The emerging nanogenerators, which harvest micro/nanomechanical energy and thermal energy from human beings and convert into electrical energy, provide an ideal solution for self‐powering of biomedical devices. The combination of nanogenerators and biomedicine has been accelerating the development of self‐powered biomedical equipment. This article first introduces the operating principle of nanogenerators and then reviews the progress of nanogenerators in biomedical applications, including power supply, smart sensing, and effective treatment. Besides, the microbial disinfection and biodegradation performances of nanogenerators have been updated. Next, the protection devices have been discussed such as face mask with air filtering function together with real‐time monitoring of human health from the respiration and heat emission. Besides, the nanogenerator devices have been categorized by the types of mechanical energy from human beings, such as the body movement, tissue and organ activities, energy from chemical reactions, and gravitational potential energy. Eventually, the challenges and future opportunities in the applications of nanogenerators are delivered in the conclusive remarks. The combination of nanogenerator and biomedicine have been accelerating the development of self‐powered biomedical devices, which show a bright future in biomedicine and healthcare such as smart sensing, and therapy.
Boosting flexible electronics with integration of two-dimensional materials
(Weinheim : Wiley, 2024) Hou, Chongyang; Zhang, Shuye; Liu, Rui; Gemming, Thomas; Bachmatiuk, Alicja; Zhao, Hongbin; Jia, Hao; Huang, Shirong; Zhou, Weijia; Xu, Jian‐Bin; Pang, Jinbo; Rümmeli, Mark H.; Bi, Jinshun; Liu, Hong; Cuniberti, Gianaurelio
Flexible electronics has emerged as a continuously growing field of study. Two-dimensional (2D) materials often act as conductors and electrodes in electronic devices, holding significant promise in the design of high-performance, flexible electronics. Numerous studies have focused on harnessing the potential of these materials for the development of such devices. However, to date, the incorporation of 2D materials in flexible electronics has rarely been summarized or reviewed. Consequently, there is an urgent need to develop comprehensive reviews for rapid updates on this evolving landscape. This review covers progress in complex material architectures based on 2D materials, including interfaces, heterostructures, and 2D/polymer composites. Additionally, it explores flexible and wearable energy storage and conversion, display and touch technologies, and biomedical applications, together with integrated design solutions. Although the pursuit of high-performance and high-sensitivity instruments remains a primary objective, the integrated design of flexible electronics with 2D materials also warrants consideration. By combining multiple functionalities into a singular device, augmented by machine learning and algorithms, we can potentially surpass the performance of existing wearable technologies. Finally, we briefly discuss the future trajectory of this burgeoning field. This review discusses the recent advancements in flexible sensors made from 2D materials and their applications in integrated architecture and device design.
Boron doping of SWCNTs as a way to enhance the thermoelectric properties of melt‐mixed polypropylene/SWCNT composites
(Basel : MDPI, 2020) Krause, Beate; Bezugly, Viktor; Khavrus, Vyacheslav; Ye, Liu; Cuniberti, Gianaurelio; Pötschke, Petra
Composites based on the matrix polymer polypropylene (PP) filled with single‐walled carbon nanotubes (SWCNTs) and boron‐doped SWCNTs (B‐SWCNTs) were prepared by melt‐mixing to analyze the influence of boron doping of SWCNTs on the thermoelectric properties of these nanocomposites. It was found that besides a significantly higher Seebeck coefficient of B‐SWCNT films and powder packages, the values for B‐SWCNT incorporated in PP were higher than those for SWCNTs. Due to the higher electrical conductivity and the higher Seebeck coefficients of B‐SWCNTs, the power factor (PF) and the figure of merit (ZT) were also higher for the PP/B‐SWCNT composites. The highest value achieved in this study was a Seebeck coefficient of 59.7 μV/K for PP with 0.5 wt% B‐SWCNT compared to 47.9 μV/K for SWCNTs at the same filling level. The highest PF was 0.78 μW/(m∙K2) for PP with 7.5 wt% B‐SWCNT. SWCNT macro‐ and microdispersions were found to be similar in both composite types, as was the very low electrical percolation threshold between 0.075 and 0.1 wt% SWCNT. At loadings between 0.5 and 2.0 wt%, B‐SWCNT‐based composites have one order of magnitude higher electrical conductivity than those based on SWCNT. The crystallization behavior of PP is more strongly influenced by B‐SWCNTs since their composites have higher crystallization temperatures than composites with SWCNTs at a comparable degree of crystallinity. Boron doping of SWCNTs is therefore a suitable way to improve the electrical and thermoelectric properties of composites. © 2020 by the authors.
Determination of the Entire Stent Surface Area by a New Analytical Method
(Basel : MDPI, 2020) Saqib, Muhammad; Bernhardt, Ricardo; Kästner, Markus; Beshchasna, Natalia; Cuniberti, Gianaurelio; Opitz, Jörg
Stenting is a widely used treatment procedure for coronary artery disease around the world. Stents have a complex geometry, which makes the characterization of their corrosion difficult due to the absence of a mathematical model to calculate the entire stent surface area (ESSA). Therefore, corrosion experiments with stents are mostly based on qualitative analysis. Additionally, the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases. At present, several methods are available to calculate the stent outer surface area (SOSA), whereas no model exists for the calculation of the ESSA. This paper presents a novel mathematical model for the calculation of the ESSA using the SOSA as one of the main parameters. The ESSA of seven magnesium alloy stents (MeKo Laser Material Processing GmbH, Sarstedt, Germany) were calculated using the developed model. The calculated SOSA and ESSA for all stents are 33.34%(±0.26%) and 111.86 mm (±0.85 mm), respectively. The model is validated by micro-computed tomography (micro-CT), with a difference of 12.34% (±0.46%). The value of corrosion rates calculated using the ESSA computed with the developed model will be 12.34% (±0.46%) less than that of using ESSA obtained by micro-CT.
Growth of all-carbon horizontally aligned single-walled carbon nanotubes nucleated from fullerene-based structures
(London : BioMed Central, 2013) Ibrahim, Imad; Zhang, Yang; Popov, Alexey; Dunsch, Lothar; Büchner, Bernd; Cuniberti, Gianaurelio; Rümmeli, Mark H.
All-carbon single-walled carbon nanotubes (SWCNTs) were successfully synthesized, nucleated using a fullerene derivative. A systematic investigation into the initial preparation of C60 fullerenes as growth nucleators for the SWCNTs was conducted. Enhancement in the yield of the produced SWCNT has been achieved with exploring different dispersing media for the fullerenes, the period, and environment of the initial thermal treatment of the fullerenes in addition to the use of different fullerene-based structures. The systematic studies significantly advance our understanding of the growth of the all-carbon catalyst-free single-walled carbon nanotubes. Field-effect transistors were fabricated using the catalyst-free SWCNT and then electrically characterized, showing current capacity as high as the well-studied catalyst-assisted nanotubes.
High-performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre-seeding strategy
(Weinheim : Wiley, 2021) Zhang, Shu; Pang, Jinbo; Cheng, Qilin; Yang, Feng; Chen, Yu; Liu, Yu; Li, Yufen; Gemming, Thomas; Liu, Xiaoyan; Ibarlucea, Bergoi; Yang, Jiali; Liu, Hong; Zhou, Weijia; Cuniberti, Gianaurelio; Rümmeli, Mark H.
Tungsten diselenide (WSe2) possesses extraordinary electronic properties for applications in electronics, optoelectronics, and emerging exciton physics. The synthesis of monolayer WSe2 film is of topmost for device arrays and integrated circuits. The monolayer WSe2 film has yet been reported by thermal chemical vapor deposition (CVD) approach, and the nucleation mechanism remains unclear. Here, we report a pre-seeding strategy for finely regulating the nuclei density at an early stage and achieving a fully covered film after chemical vapor deposition growth. The underlying mechanism is heterogeneous nucleation from the pre-seeding tungsten oxide nanoparticles. At first, we optimized the precursor concentration for pre-seeding. Besides, we confirmed the superiority of the pre-seeding method, compared with three types of substrate pretreatments, including nontreatment, sonication in an organic solvent, and oxygen plasma. Eventually, the high-quality synthetic WSe2 monolayer film exhibits excellent device performance in field-effect transistors and photodetectors. We extracted thermodynamic activation energy from the nucleation and growth data. Our results may shed light on the wafer-scale production of homogeneous monolayer films of WSe2, other 2D materials, and their van der Waals heterostructures.
Impact of surface charge on the motion of light-activated Janus micromotors
(Berlin ; Heidelberg : Springer, 2021) Huang, Tao; Ibarlucea, Bergoi; Caspari, Anja; Synytska, Alla; Cuniberti, Gianaurelio; de Graaf, Joost; Baraban, Larysa
Control over micromotors' motion is of high relevance for lab-on-a-chip and biomedical engineering, wherein such particles encounter complex microenvironments. Here, we introduce an efficient way to influence Janus micromotors' direction of motion and speed by modifying their surface properties and those of their immediate surroundings. We fabricated light-responsive Janus micromotors with positive and negative surface charge, both driven by ionic self-diffusiophoresis. These were used to observe direction-of-motion reversal in proximity to glass substrates for which we varied the surface charge. Quantitative analysis allowed us to extract the dependence of the particle velocity on the surface charge density of the substrate. This constitutes the first quantitative demonstration of the substrate's surface charge on the motility of the light-activated diffusiophoretic motors in water. We provide qualitative understanding of these observations in terms of osmotic flow along the substrate generated through the ions released by the propulsion mechanism. Our results constitute a crucial step in moving toward practical application of self-phoretic artificial micromotors.
In-situ quasi-instantaneous e-beam driven catalyst-free formation of crystalline aluminum borate nanowires
(London : Nature Publishing Group, 2016) Gonzalez-Martinez, Ignacio G.; Gemming, Thomas; Mendes, Rafael; Bachmatiuk, Alicja; Bezugly, Viktor; Kunstmann, Jens; Eckert, Jürgen; Cuniberti, Gianaurelio; Rümmeli, Mark H.
The catalyst-assisted nucleation and growth mechanisms for many kinds of nanowires and nanotubes are pretty well understood. At times, though, 1D nanostructures form without a catalyst and the argued growth modes have inconsistencies. One such example is the catalyst-free growth of aluminium borate nanowires. Here we develop an in-situ catalyst-free room temperature growth route for aluminium nanowires using the electron beam in a transmission electron microscope. We provide strong experimental evidence that supports a formation process that can be viewed as a phase transition in which the generation of free-volume induced by the electron beam irradiation enhances the atomic mobility within the precursor material. The enhanced atomic mobility and specific features of the crystal structure of Al5BO9 drive the atomic rearrangement that results in the large scale formation of highly crystalline aluminium borate nanowires. The whole formation process can be completed within fractions of a second. Our developed growth mechanism might also be extended to describe the catalyst-free formation of other nanowires.
Magnetofluidic platform for multidimensional magnetic and optical barcoding of droplets
(Cambridge : RSC, 2014) Lin, Gungun; Makarov, Denys; Medina-Sánchez, Mariana; Guix, Maria; Baraban, Larysa; Cuniberti, Gianaurelio; Schmidt, Oliver G.
We present a concept of multidimensional magnetic and optical barcoding of droplets based on a magnetofluidic platform. The platform comprises multiple functional areas, such as an encoding area, an encoded droplet pool and a magnetic decoding area with integrated giant magnetoresistive (GMR) sensors. To prove this concept, penicillin functionalized with fluorescent dyes is coencapsulated with magnetic nanoparticles into droplets. While fluorescent dyes are used as conventional optical barcodes which are decoded with an optical decoding setup, an additional dimensionality of barcodes is created by using magnetic nanoparticles as magnetic barcodes for individual droplets and integrated micro-patterned GMR sensors as the corresponding magnetic decoding devices. The strategy of incorporating a magnetic encoding scheme provides a dynamic range of ~40 dB in addition to that of the optical method. When combined with magnetic barcodes, the encoding capacity can be increased by more than 1 order of magnitude compared with using only optical barcodes, that is, the magnetic platform provides more than 10 unique magnetic codes in addition to each optical barcode. Besides being a unique magnetic functional element for droplet microfluidics, the platform is capable of on-demand facile magnetic encoding and real-time decoding of droplets which paves the way for the development of novel non-optical encoding schemes for highly multiplexed droplet-based biological assays.
Monitoring microbial metabolites using an inductively coupled resonance circuit
(London : Nature Publishing Group, 2015) Karnaushenko, Daniil; Baraban, Larysa; Ye, Dan; Uguz, Ilke; Mendes, Rafael G.; Rümmeli, Mark H.; de Visser, J. Arjan G.M.; Schmidt, Oliver G.; Cuniberti, Gianaurelio; Makarov, Denys
We present a new approach to monitor microbial population dynamics in emulsion droplets via changes in metabolite composition, using an inductively coupled LC resonance circuit. The signal measured by such resonance detector provides information on the magnetic field interaction with the bacterial culture, which is complementary to the information accessible by other detection means, based on electric field interaction, i.e. capacitive or resistive, as well as optical techniques. Several charge-related factors, including pH and ammonia concentrations, were identified as possible contributors to the characteristic of resonance detector profile. The setup enables probing the ionic byproducts of microbial metabolic activity at later stages of cell growth, where conventional optical detection methods have no discriminating power.
Polymerization driven monomer passage through monolayer chemical vapour deposition graphene
([London] : Nature Publishing Group UK, 2018-10-3) Zhang, Tao; Liao, Zhongquan; Sandonas, Leonardo Medrano; Dianat, Arezoo; Liu, Xiaoling; Xiao, Peng; Amin, Ihsan; Gutierrez, Rafael; Chen, Tao; Zschech, Ehrenfried; Cuniberti, Gianaurelio; Jordan, Rainer
Mass transport through graphene is receiving increasing attention due to the potential for molecular sieving. Experimental studies are mostly limited to the translocation of protons, ions, and water molecules, and results for larger molecules through graphene are rare. Here, we perform controlled radical polymerization with surface-anchored self-assembled initiator monolayer in a monomer solution with single-layer graphene separating the initiator from the monomer. We demonstrate that neutral monomers are able to pass through the graphene (via native defects) and increase the graphene defects ratio (Raman ID/IG) from ca. 0.09 to 0.22. The translocations of anionic and cationic monomers through graphene are significantly slower due to chemical interactions of monomers with the graphene defects. Interestingly, if micropatterned initiator-monolayers are used, the translocations of anionic monomers apparently cut the graphene sheet into congruent microscopic structures. The varied interactions between monomers and graphene defects are further investigated by quantum molecular dynamics simulations.
Real-Time Monitoring of Blood Parameters in the Intensive Care Unit: State-of-the-Art and Perspectives
(Basel : MDPI, 2022) Bockholt, Rebecca; Paschke, Shaleen; Heubner, Lars; Ibarlucea, Bergoi; Laupp, Alexander; Janićijević, Željko; Klinghammer, Stephanie; Balakin, Sascha; Maitz, Manfred F.; Werner, Carsten; Cuniberti, Gianaurelio; Baraban, Larysa; Spieth, Peter Markus
The number of patients in intensive care units has increased over the past years. Critically ill patients are treated with a real time support of the instruments that offer monitoring of relevant blood parameters. These parameters include blood gases, lactate, and glucose, as well as pH and tem-perature. Considering the COVID-19 pandemic, continuous management of dynamic deteriorating parameters in patients is more relevant than ever before. This narrative review aims to summarize the currently available literature regarding real-time monitoring of blood parameters in intensive care. Both, invasive and non-invasive methods are described in detail and discussed in terms of general advantages and disadvantages particularly in context of their use in different medical fields but especially in critical care. The objective is to explicate both, well-known and frequently used as well as relatively unknown devices. Furtehrmore, potential future direction in research and development of realtime sensor systems are discussed. Therefore, the discussion section provides a brief description of current developments in biosensing with special emphasis on their technical implementation. In connection with these developments, the authors focus on different electrochemical approaches to invasive and non-invasive measurements in vivo.
STM induced manipulation of azulene-based molecules and nanostructures: the role of the dipole moment
(Cambridge : RSC Publ., 2020) Kühne, Tim; Au-Yeung, Kwan Ho; Eisenhut, Frank; Aiboudi, Oumaima; Ryndyk, Dmitry A.; Cuniberti, Gianaurelio; Lissel, Franziska; Moresco, Francesca
Among the different mechanisms that can be used to drive a molecule on a surface by the tip of a scanning tunneling microscope at low temperature, we used voltage pulses to move azulene-based single molecules and nanostructures on Au(111). Upon evaporation, the molecules partially cleave and form metallo-organic dimers while single molecules are very scarce, as confirmed by simulations. By applying voltage pulses to the different structures under similar conditions, we observe that only one type of dimer can be controllably driven on the surface, which has the lowest dipole moment of all investigated structures. Experiments under different bias and tip height conditions reveal that the electric field is the main driving force of the directed motion. We discuss the different observed structures and their movement properties with respect to their dipole moment and charge distribution on the surface.
Surface modification of silicon nanowire based field effect transistors with stimuli responsive polymer brushes for biosensing applications
(Basel : MDPI, 2020) Klinghammer, Stephanie; Rauch, Sebastian; Pregl, Sebastian; Uhlmann, Petra; Baraban, Larysa; Cuniberti, Gianaurelio
We demonstrate the functionalization of silicon nanowire based field effect transistors (SiNW FETs) FETs with stimuli-responsive polymer brushes of poly(N-isopropylacrylamide) (PNIPAAM) and poly(acrylic acid) (PAA). Surface functionalization was confirmed by atomic force microscopy, contact angle measurements, and verified electrically using a silicon nanowire based field effect transistor sensor device. For thermo-responsive PNIPAAM, the physicochemical properties (i.e., a reversible phase transition, wettability) were induced by crossing the lower critical solution temperature (LCST) of about 32 C. Taking advantage of this property, osteosarcomic SaoS-2 cells were cultured on PNIPAAM-modified sensors at temperatures above the LCST, and completely detached by simply cooling. Next, the weak polyelectrolyte PAA, that is sensitive towards alteration of pH and ionic strength, was used to cover the silicon nanowire based device. Here, the increase of pH will cause deprotonation of the present carboxylic (COOH) groups along the chains into negatively charged COO- moieties that repel each other and cause swelling of the polymer. Our experimental results suggest that this functionalization enhances the pH sensitivity of the SiNW FETs. Specific receptor (bio-)molecules can be added to the polymer brushes by simple click chemistry so that functionality of the brush layer can be tuned optionally. We demonstrate at the proof-of concept-level that osteosarcomic Saos-2 cells can adhere to PNIPAAM-modified FETs, and cell signals could be recorded electrically. This study presents an applicable route for the modification of highly sensitive, versatile FETs that can be applied for detection of a variety of biological analytes. © 2020 by the authors.
Synthesis of carbon nanotubes with and without catalyst particles
(London : BioMed Central, 2011) Rümmeli, Mark Hermann; Bachmatiuk, Alicja; Börrnert, Felix; Schäffel, Franziska; Ibrahim, Imad; Cendrowsk, Krzysztof; Simha-Martynkova, Grazyna; Plachá, Daniela; Cuniberti, Gianaurelio; Büchner, Bernd
The initial development of carbon nanotube synthesis revolved heavily around the use of 3d valence transition metals such as Fe, Ni, and Co. More recently, noble metals (e.g. Au) and poor metals (e.g. In, Pb) have been shown to also yield carbon nanotubes. In addition, various ceramics and semiconductors can serve as catalytic particles suitable for tube formation and in some cases hybrid metal/metal oxide systems are possible. All-carbon systems for carbon nanotube growth without any catalytic particles have also been demonstrated. These different growth systems are briefly examined in this article and serve to highlight the breadth of avenues available for carbon nanotube synthesis.
Two-Dimensional Boronate Ester Covalent Organic Framework Thin Films with Large Single Crystalline Domains for a Neuromorphic Memory Device
(Weinheim : Wiley-VCH, 2020) Park, SangWook; Liao, Zhongquan; Ibarlucea, Bergoi; Qi, Haoyuan; Lin, Hung-Hsuan; Becker, Daniel; Melidonie, Jason; Zhang, Tao; Sahabudeen, Hafeesudeen; Baraban, Larysa; Baek, Chang-Ki; Zheng, Zhikun; Zschech, Ehrenfried; Fery, Andreas; Heine, Thomas; Kaiser, Ute; Cuniberti, Gianaurelio; Dong, Renhao; Feng, Xinliang
Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin-film through solvothermal method and on-solid-surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin-film processability and device integration associated with the control of film thickness, layer orientation, stability and crystallinity. Moreover, although the crystalline domain sizes of the powder samples can reach micrometer scale (up to ≈1.5 μm), the reported thin-film samples have so far rather small crystalline domains up to 100 nm. Here we demonstrate a general and efficient synthesis of crystalline two-dimensional (2D) BECOF films composed of porphyrin macrocycles and phenyl or naphthyl linkers (named as 2D BECOF-PP or 2D BECOF-PN) by employing a surfactant-monolayer-assisted interfacial synthesis (SMAIS) on the water surface. The achieved 2D BECOF-PP is featured as free-standing thin film with large single-crystalline domains up to ≈60 μm2 and tunable thickness from 6 to 16 nm. A hybrid memory device composed of 2D BECOF-PP film on silicon nanowire-based field-effect transistor is demonstrated as a bio-inspired system to mimic neuronal synapses, displaying a learning–erasing–forgetting memory process. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
Understanding the catalyst-free transformation of amorphous carbon into graphene by current-induced annealing
(London : Nature Publishing Group, 2013) Barreiro, Amelia; Börrnert, Felix; Avdoshenko, Stanislav M.; Rellinghaus, Bernd; Cuniberti, Gianaurelio; Rümmeli, Mark H.; Vandersypen, Lieven M.K.
We shed light on the catalyst-free growth of graphene from amorphous carbon (a–C) by current-induced annealing by witnessing the mechanism both with in-situ transmission electron microscopy and with molecular dynamics simulations. Both in experiment and in simulation, we observe that small a–C clusters on top of a graphene substrate rearrange and crystallize into graphene patches. The process is aided by the high temperatures involved and by the van der Waals interactions with the substrate. Furthermore, in the presence of a–C, graphene can grow from the borders of holes and form a seamless graphene sheet, a novel finding that has not been reported before and that is reproduced by the simulations as well. These findings open up new avenues for bottom-up engineering of graphene-based devices.
A wafer-scale two-dimensional platinum monosulfide ultrathin film via metal sulfurization for high performance photoelectronics
(Cambridge : Royal Society of Chemistry, 2022) Pang, Jinbo; Wang, Yanhao; Yang, Xiaoxin; Zhang, Lei; Li, Yufen; Zhang, Yu; Yang, Jiali; Yang, Feng; Wang, Xiao; Cuniberti, Gianaurelio; Liu, Hong; Rümmeli, Mark H.
2D nonlayered materials have attracted enormous research interests due to their novel physical and chemical properties with confined dimensions. Platinum monosulfide as one of the most common platinum-group minerals has been less studied due to either the low purity in the natural product or the extremely high-pressure conditions for synthesis. Recently, platinum monosulfide (PtS) 2D membranes have emerged as rising-star materials for fundamental Raman and X-ray photoelectron spectral analysis as well as device exploration. However, a large-area homogeneous synthesis route has not yet been proposed and released. In this communication, we report a facile metal sulfurization strategy for the synthesis of a 4-inch wafer-scale PtS film. Enhanced characterization tools have been employed for thorough analysis of the crystal structure, chemical environment, vibrational modes, and atomic configuration. Furthermore, through theoretical calculations the phase diagram of the Pt–S compound has been plotted for showing the successful formation of PtS in our synthesis conditions. Eventually, a high-quality PtS film has been reflected in device demonstration by a photodetector. Our approach may shed light on the mass production of PtS films with precise control of their thickness and homogeneity as well as van der Waals heterostructures and related electronic devices.

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