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2. Probing Ion Diffusion and Ion Sieving through Hollow Porous Silica Shells by Imaging the Mobility of Colloids Inside the Shells.

Author

Watanabe, Kanako, Welling, Tom A. J., Mendes, Rafael G., Peimanifard, Zahra, Bransen, Maarten, Namigata, Hikaru, van Huis, Marijn A., Nagao, Daisuke, and van Blaaderen, Alfons

Subjects
POROUS silica, MESOPOROUS silica, POROUS materials, ELECTROLYTE solutions, RANGE of motion of joints
Abstract

Ionic transport through porous membranes and porous materials has received enormous attention due to its importance to many applications. An innovative methodology is proposed to study ion diffusion and ion sieving through mesoporous silica membranes (shells). The mobility of fluorescently labeled core particles within a hollow porous shell, filled with an index‐matched electrolyte solution, is observed using confocal laser scanning microscopy. The core motion range, i.e., the area explored by the core within the hollow compartment, sensitively changed depending on the local ionic concentration. Monitoring transitions in the core motion range is a practical way to detect which ions can migrate through the shells and on what timescale. For instance, lithium and chloride ions easily diffused through the porous silica shells, resulting in a core motion range that changed relatively quickly upon change of the ion concentrations outside of the shell. However, the motion range changed significantly slower upon changing to a bigger cation (tetraoctylammonium ion). This proof of principle experiment can be explained by the Gibbs‐Donnan effect, revealing that the detection of core motion ranges is a good probe to measure both ion diffusion and ion sieving through porous membranes. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Characterization of the Edge States in Colloidal Bi2Se3 Platelets

Author

Moes, Jesper R., primary, Vliem, Jara F., additional, de Melo, Pedro M. M. C., additional, Wigmans, Thomas C., additional, Botello-Méndez, Andrés R., additional, Mendes, Rafael G., additional, van Brenk, Ella F., additional, Swart, Ingmar, additional, Maisel Licerán, Lucas, additional, Stoof, Henk T. C., additional, Delerue, Christophe, additional, Zanolli, Zeila, additional, and Vanmaekelbergh, Daniel, additional

Published
2024
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6. Unraveling the Formation of Ternary AgCuSe Crystalline Nanophases and Their Potential as Antibacterial Agents

Author

Lin, Mengxi, Vargas, Beatriz, Yedra, Lluís, van Gog, Heleen, van Huis, Marijn A., Mendes, Rafael G., Llorca, Jordi, Estruch-Blasco, Manel, Pernia Leal, Manuel, Pajuelo, Eloísa, Estradé, Sònia, Peiró, Francesca, Rodríguez, Laura, and Figuerola, Albert

Abstract

AgCuSe nanoparticles could contribute to the growth of strongly light-absorbing thin films and solids with fast ion mobility, among other potential properties. Nevertheless, few methods have been developed so far for the synthesis of AgCuSe nanoparticles, and those reported deliver nanostructures with relatively large sizes and broad size and shape distributions. In this work, a colloidal cation exchange method is established for the easy synthesis of AgCuSe NPs with ca. 8 nm diameters and narrow size dispersion. Notably, in this lower size range the conucleation and growth of two stoichiometric ternary compounds are generally observed, namely the well-known eucairiteAgCuSe compound and the novel fischesserite-like Ag3CuSe2phase, the latter being less thermodynamically stable as predicted computationally and assessed experimentally. An optimal range of Cu/Ag precursor molar ratio has been identified to ensure the growth of ternary nanoparticles and, more specifically, that of the metastable Ag3CuSe2nanophase isolated for the first occasion. The attained size range for the material paves the way for utilizing AgCuSe nanoparticles in new ways within the field of biomedicine: the results obtained here confirm the antibacterial activity of the new AgxCuySeznanoparticles against Gram-positive bacteria, with significantly low values of the minimal inhibitory concentration.

Published
2024
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7. Characterization of the Edge States in Colloidal Bi2Se3 Platelets

Author

Moes, Jesper R., Vliem, Jara F., Monteiro Campos de Melo, Pedro, Wigmans, Thomas C., Botello-Méndez, Andrés R., Mendes, Rafael G., Brenk, Ella F. van, Swart, Ingmar, Licerán, Lucas Maisel, Stoof, Henk, Delerue, Christophe, Zanolli, Zeila, Vanmaekelbergh, Daniel, Moes, Jesper R., Vliem, Jara F., Monteiro Campos de Melo, Pedro, Wigmans, Thomas C., Botello-Méndez, Andrés R., Mendes, Rafael G., Brenk, Ella F. van, Swart, Ingmar, Licerán, Lucas Maisel, Stoof, Henk, Delerue, Christophe, Zanolli, Zeila, and Vanmaekelbergh, Daniel

Abstract

The remarkable development of colloidal nanocrystals with controlled dimensions and surface chemistry has resulted in vast optoelectronic applications. But can they also form a platform for quantum materials, in which electronic coherence is key? Here, we use colloidal, two-dimensional Bi2Se3 crystals, with precise and uniform thickness and finite lateral dimensions in the 100 nm range, to study the evolution of a topological insulator from three to two dimensions. For a thickness of 4–6 quintuple layers, scanning tunneling spectroscopy shows an 8 nm wide, nonscattering state encircling the platelet. We discuss the nature of this edge state with a low-energy continuum model and ab initio GW-Tight Binding theory. Our results also provide an indication of the maximum density of such states on a device.

Published
2024

8. Reversible MnO to Mn3O4 Oxidation in Manganese Oxide Nanoparticles

Author

de Boer, Roos M., van Huis, Marijn A., Mendes, Rafael G., de Boer, Roos M., van Huis, Marijn A., and Mendes, Rafael G.

Abstract

Manganese is an attractive element for sustainable solutions. It is largely available in the earth's crust, making it ideal for cost-effective and large-scale applications. Especially MnO nanoparticles have recently received attention for applications in battery technology. However, manganese has many oxidation states that are energetically very similar, indicating that they may easily transform from one to the other. Herein, the reversible oxidation of MnO nanoparticles to Mn3O4 studied with in situ transmission electron microscopy is shown. The oxygen sublattices of MnO and Mn3O4 are found to be perfectly aligned, and an atomic mechanism where the transformation is facilitated by the migration of Mn cations on the shared O sublattice is proposed. Even when protected with an amorphous carbon layer, MnO particles are highly unstable and oxidize to Mn3O4 in ethanol. The poor stability of MnO lacks discussion in many battery-related works, and strategies aimed at avoiding this should be developed.

Published
2024

9. Characterization of the Edge States in Colloidal Bi2Se3 Platelets

Author

Condensed Matter and Interfaces, Theoretical Physics, Soft Condensed Matter and Biophysics, Sub Condensed Matter and Interfaces, Sub Education Institute Chemistry, Sub Soft Condensed Matter, Sub Cond-Matter Theory, Stat & Comp Phys, Moes, Jesper R., Vliem, Jara F., Monteiro Campos de Melo, Pedro, Wigmans, Thomas C., Botello-Méndez, Andrés R., Mendes, Rafael G., Brenk, Ella F. van, Swart, Ingmar, Licerán, Lucas Maisel, Stoof, Henk, Delerue, Christophe, Zanolli, Zeila, Vanmaekelbergh, Daniel, Condensed Matter and Interfaces, Theoretical Physics, Soft Condensed Matter and Biophysics, Sub Condensed Matter and Interfaces, Sub Education Institute Chemistry, Sub Soft Condensed Matter, Sub Cond-Matter Theory, Stat & Comp Phys, Moes, Jesper R., Vliem, Jara F., Monteiro Campos de Melo, Pedro, Wigmans, Thomas C., Botello-Méndez, Andrés R., Mendes, Rafael G., Brenk, Ella F. van, Swart, Ingmar, Licerán, Lucas Maisel, Stoof, Henk, Delerue, Christophe, Zanolli, Zeila, and Vanmaekelbergh, Daniel

Published
2024

10. Reversible MnO to Mn3O4 Oxidation in Manganese Oxide Nanoparticles

Author

Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, de Boer, Roos M., van Huis, Marijn A., Mendes, Rafael G., Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, de Boer, Roos M., van Huis, Marijn A., and Mendes, Rafael G.

Published
2024

11. In Situ Growth of Suspended Zirconene Islets Inside Graphene Pores.

Author

Mendes, Rafael G., Ta, Huy Quang, Gemming, Thomas, Gog, Heleen, Huis, Marijn A., Bachmatiuk, Alicja, and Rümmeli, Mark H.

Subjects
*TRANSMISSION electron microscopes, *TRANSMISSION electron microscopy, *EXTREME environments, *ZIRCONIUM, *ISLANDS
Abstract

Experiments using a transmission electron microscope decomposed zirconium acetylacetonate with an electron beam, forming zirconium nanoparticles on graphene. Continued electron irradiation transformed these nanoparticles into atomically thick zirconium islets (zirconene islets) within the graphene lattice. The electron beam caused zirconium atom dislocations and vacancies that are rapidly refilled, a process repeating until the vacancies evolved into zirconium nanoribbons before breaking. This study offers insights into the electron‐driven growth and degradation of zirconene islets, showcasing a method to fabricate freestanding zirconenes for use as atomically thin coatings in extreme environments. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Nanoscale Porosity of High Surface Area Gadolinium Oxide Nanofoam Obtained With Combustion Synthesis

Author

de Boer, Roos M., Chen, Xiaodan, Cvejn, Daniel, Peterek Dědková, Kateřina, van Huis, Marijn A., Mendes, Rafael G., de Boer, Roos M., Chen, Xiaodan, Cvejn, Daniel, Peterek Dědková, Kateřina, van Huis, Marijn A., and Mendes, Rafael G.

Abstract

Nanoscale gadolinium oxide (Gd2O3) is a promising nanomaterial with unique physicochemical properties that finds various applications ranging from biomedicine to catalysis. The preparation of highly porous Gd2O3 nanofoam greatly increases its surface area thereby boosting its potential for functional use in applications such as water purification processes and in catalytic applications. By using the combustion synthesis method, a strong exothermic redox reaction between gadolinium nitrate hexahydrate and glycine causes the formation of crystalline nanoporous Gd2O3. In this study, the synthesis of Gd2O3 nanofoam is achieved with combustion synthesis at large scale (grams). Its nanoscale porosity is investigated by nitrogen physisorption and its nanoscale 3D structure by electron tomography, and the formation process is investigated as well by means of in situ heating inside the transmission electron microscope. The bulk nanofoam product is highly crystalline and porous with a surface area of 67 m2 g−1 as measured by physisorption, in good agreement with the electron tomographic 3D reconstructions showing an intricate interconnected pore network with pore sizes varying from 2 to 3 nm to tens of nanometers. In situ heating experiments point to many possibilities for tuning the porosity of the Gd2O3 nanofoam by varying the experimental synthesis conditions.

Published
2023

17. Nanoscale Porosity of High Surface Area Gadolinium Oxide Nanofoam Obtained With Combustion Synthesis

Author

Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, de Boer, Roos M., Chen, Xiaodan, Cvejn, Daniel, Peterek Dědková, Kateřina, van Huis, Marijn A., Mendes, Rafael G., Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, de Boer, Roos M., Chen, Xiaodan, Cvejn, Daniel, Peterek Dědková, Kateřina, van Huis, Marijn A., and Mendes, Rafael G.

Published
2023

22. General synthesis of 2D rare-earth oxide single crystals with tailorable facets

Author

Li, Linyang, primary, Lu, Fangyun, additional, Xiong, Wenqi, additional, Ding, Yu, additional, Lu, Yangyi, additional, Xiao, Yao, additional, Tong, Xin, additional, Wang, Yao, additional, Jia, Shuangfeng, additional, Wang, Jianbo, additional, Mendes, Rafael G, additional, Rümmeli, Mark H, additional, Yuan, Shengjun, additional, Zeng, Mengqi, additional, and Fu, Lei, additional

Published
2021
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23. Tailoring the stoichiometry of C3N4 nanosheets under electron beam irradiation

Author

Mendes, Rafael G., Ta, Huy Q., Yang, Xiaoqin, Bachmatiuk, Alicja, Praus, Petr, Mamakhel, Aref, Iversen, Bo B., Su, Ren, Gemming, Thomas, Rümmeli, Mark H., Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Sub Soft Condensed Matter, and Soft Condensed Matter and Biophysics

Subjects
chemistry.chemical_classification, Materials science, Double bond, Dopant, Graphitic carbon nitride, General Physics and Astronomy, 02 engineering and technology, Inelastic scattering, Physics and Astronomy(all), 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, chemistry.chemical_compound, chemistry, Transmission electron microscopy, Chemical physics, Physical and Theoretical Chemistry, 0210 nano-technology, Carbon nitride, Current density, Stoichiometry
Abstract

Two-dimensional polymeric graphitic carbon nitride (g-C3N4) is a low-cost material with versatile properties that can be enhanced by the introduction of dopant atoms and by changing the degree of polymerization/stoichiometry, which offers significant benefits for numerous applications. Herein, we investigate the stability of g-C3N4under electron beam irradiation inside a transmission electron microscope operating at different electron acceleration voltages. Our findings indicate that the degradation of g-C3N4occurs with N species preferentially removed over C species. However, the precise nitrogen group from which N is removed from g-C3N4(C-N-C, NH or -NH2) is unclear. Moreover, the rate of degradation increases with decreasing electron acceleration voltage, suggesting that inelastic scattering events (radiolysis) dominate over elastic events (knock-on damage). The rate of degradation by removing N atoms is also sensitive to the current density. Hence, we demonstrate that both the electron acceleration voltage and the current density are parameters with which one can use to control the stoichiometry. Moreover, as N species were preferentially removed, thed-spacing of the carbon nitride structure increased. These findings provide a deeper understanding of g-C3N4

Published
2021
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24. Phase constitution and microstructure of the NbTiVZr refractory high-entropy alloy solidified upon different processing

Author

Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Andreoli, Angelo F., Mendes, Rafael G., Witusiewicz, Victor T., Shuleshova, Olga, van Huis, Marijn A., Nielsch, Kornelius, Kaban, Ivan, Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Andreoli, Angelo F., Mendes, Rafael G., Witusiewicz, Victor T., Shuleshova, Olga, van Huis, Marijn A., Nielsch, Kornelius, and Kaban, Ivan

Published
2021

25. Tailoring the stoichiometry of C3N4 nanosheets under electron beam irradiation

Author

Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Mendes, Rafael G., Ta, Huy Q., Yang, Xiaoqin, Bachmatiuk, Alicja, Praus, Petr, Mamakhel, Aref, Iversen, Bo B., Su, Ren, Gemming, Thomas, Rümmeli, Mark H., Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Mendes, Rafael G., Ta, Huy Q., Yang, Xiaoqin, Bachmatiuk, Alicja, Praus, Petr, Mamakhel, Aref, Iversen, Bo B., Su, Ren, Gemming, Thomas, and Rümmeli, Mark H.

Published
2021

26. In-situ observations of novel single-atom thick 2D tin membranes embedded in graphene

Author

Section Economic Urban Transitions, Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Yang, Xiaoqin, Ta, Huy Q., Li, Wei, Mendes, Rafael G., Liu, Yu, Shi, Qitao, Ullah, Sami, Bachmatiuk, Alicja, Luo, Jinping, Liu, Lijun, Choi, Jin Ho, Rummeli, Mark H., Section Economic Urban Transitions, Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Yang, Xiaoqin, Ta, Huy Q., Li, Wei, Mendes, Rafael G., Liu, Yu, Shi, Qitao, Ullah, Sami, Bachmatiuk, Alicja, Luo, Jinping, Liu, Lijun, Choi, Jin Ho, and Rummeli, Mark H.

Published
2021

27. In Situ Formation of Free-Standing Single-Atom-Thick Antiferromagnetic Chromium Membranes

Author

Ta, Huy Quang, Yang, Qin Xiao, Liu, Shuyuan, Bachmatiuk, A., Mendes, Rafael G., Gemming, Thomas, Liu, Yu, Liu, Lijun, Tokarska, Klaudia, Patel, Rajen B., Choi, Jin Ho, Rümmeli, Mark H., Sub Soft Condensed Matter, and Soft Condensed Matter and Biophysics

Subjects
In situ TEM, free-standing single-atom-thick membrane, antiferromagnetic, chromium, single-element 2D, 2D metals
Abstract

Compared to van der Waals two-dimensional (2D) layers with lateral covalent bonds, metallic bonding systems favor close-packed structures, and thus, free-standing 2D metals have remained, for the most part, elusive. However, a number of theoretical studies suggest a number of metals can exist as 2D materials and a few early experiments support this notion. Here we demonstrate free-standing single-atom-thick crystalline chromium (Cr) suspended membranes using aberration-corrected transmission electron microscopy and image simulations. Density functional theory studies confirm the 2D Cr membranes have an antiferromagnetic ground state making them highly attractive for spintronic applications. Moreover, the work also helps consolidate the existence of a new family of 2D metal layers.

Published
2020

28. In situ observations of freestanding single-atom-thick gold nanoribbons suspended in graphene

Author

Zhao, Liang, Ta, Huy Q., Mendes, Rafael G., Bachmatiuk, Alicja, Rummeli, Mark H., Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Sub Soft Condensed Matter, and Soft Condensed Matter and Biophysics

Subjects
In situ, Materials science, Graphene, Mechanical Engineering, Atom (order theory), Molecular physics, in situ TEM, law.invention, electron beam irradiation, Electron beam irradiation, Mechanics of Materials, law, gold nanoribbons, single-atom-thick
Abstract

Bulk gold's attributes of relative chemical inertness, rarity, relatively low melting point and its beautiful sheen make it a prized material for humans. Recordings suggest it was the first metal employed by humans dating as far back to the late Paleolithic period approximate to 40 000 BC. However, at the nanoscale gold is expected to present new and exciting properties, not least in catalysis. Moreover, recent studies suggest a new family of single-atom-thick two-dimensional (2D) metals exist. This work shows single-atom-thick freestanding gold membranes and nanoribbons can form as suspended structures in graphene pores. Electron irradiation is shown to lead to changes to the graphene pores which lead to dynamic changes of the gold membranes which transition to a nanoribbon. The freestanding single-atom-thick 2D gold structures are relatively stable to electron irradiation for extended periods. The work should advance the development of 2D gold monolayers significantly. Web of Science art. no. 2000436

Published
2020

29. Bandgap tuning of two-dimensional materials by sphere diameter engineering

Author

Sub Soft Condensed Matter, Veterinaire biochemie, Soft Condensed Matter and Biophysics, Zeng, Mengqi, Liu, Jinxin, Zhou, Lu, Mendes, Rafael G., Dong, Yongqi, Zhang, Min Ye, Cui, Zhi Hao, Cai, Zhonghou, Zhang, Zhan, Zhu, Daming, Yang, Tieying, Li, Xiaolong, Wang, Jianqiang, Zhao, Liang, Chen, Guoxian, Jiang, Hong, Rümmeli, Mark H., Zhou, Hua, Fu, Lei, Sub Soft Condensed Matter, Veterinaire biochemie, Soft Condensed Matter and Biophysics, Zeng, Mengqi, Liu, Jinxin, Zhou, Lu, Mendes, Rafael G., Dong, Yongqi, Zhang, Min Ye, Cui, Zhi Hao, Cai, Zhonghou, Zhang, Zhan, Zhu, Daming, Yang, Tieying, Li, Xiaolong, Wang, Jianqiang, Zhao, Liang, Chen, Guoxian, Jiang, Hong, Rümmeli, Mark H., Zhou, Hua, and Fu, Lei

Published
2020

31. In Situ Formation of Free-Standing Single-Atom-Thick Antiferromagnetic Chromium Membranes

Author

Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Ta, Huy Quang, Yang, Qin Xiao, Liu, Shuyuan, Bachmatiuk, A., Mendes, Rafael G., Gemming, Thomas, Liu, Yu, Liu, Lijun, Tokarska, Klaudia, Patel, Rajen B., Choi, Jin Ho, Rümmeli, Mark H., Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Ta, Huy Quang, Yang, Qin Xiao, Liu, Shuyuan, Bachmatiuk, A., Mendes, Rafael G., Gemming, Thomas, Liu, Yu, Liu, Lijun, Tokarska, Klaudia, Patel, Rajen B., Choi, Jin Ho, and Rümmeli, Mark H.

Published
2020

33. General synthesis of 2D rare-earth oxide single crystals with tailorable facets.

Author

Li, Linyang, Lu, Fangyun, Xiong, Wenqi, Ding, Yu, Lu, Yangyi, Xiao, Yao, Tong, Xin, Wang, Yao, Jia, Shuangfeng, Wang, Jianbo, Mendes, Rafael G, Rümmeli, Mark H, Yuan, Shengjun, Zeng, Mengqi, and Fu, Lei

Subjects
SINGLE crystals, MAGNETIC properties, CRYSTALS, OXIDES
Abstract

Two-dimensional (2D) rare-earth oxides (REOs) are a large family of materials with various intriguing applications and precise facet control is essential for investigating new properties in the 2D limit. However, a bottleneck remains with regard to obtaining their 2D single crystals with specific facets because of the intrinsic non-layered structure and disparate thermodynamic stability of different facets. Herein, for the first time, we achieve the synthesis of a wide variety of high-quality 2D REO single crystals with tailorable facets via designing a hard-soft-acid-base couple for controlling the 2D nucleation of the predetermined facets and adjusting the growth mode and direction of crystals. Also, the facet-related magnetic properties of 2D REO single crystals were revealed. Our approach provides a foundation for further exploring other facet-dependent properties and various applications of 2D REO, as well as inspiration for the precise growth of other non-layered 2D materials. [ABSTRACT FROM AUTHOR]

Published
2022
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36. Correction: Direct chemical vapor deposition synthesis of large area single-layer brominated grapheme (RSC Advances (2019) 9 (13527-13532) DOI: 10.1039/C9RA01152H)

Author

Hasan, Maria, Meiou, Wang, Yulian, Liu, Ullah, Sami, Ta, Huy Q., Zhao, Liang, Mendes, Rafael G., Malik, Zahida P., Ahmad, Nasir M., Liu, Zhongfan, and R��Ummeli, Mark H.

Abstract

Correction for ���Direct chemical vapor deposition synthesis of large area single-layer brominated graphene��� by Maria Hasan et al., RSC Adv., 2019, 9, 13527���13532. In the Acknowledgements section, the attribution ���the Czech Republic from ERDF ���Institute of Environmental Technology ��� Excellent Research��� (No. CZ.02.1.01/0.0/0.0/15_019/0000853), should read ���the Czech Republic from ERDF OP RDE project No. CZ.02.1.01/0.0/0.0/16_019/0000853���. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

Published
2019
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37. Highly Dispersed ZnO Sites in a ZnO/ZrO2 Catalyst Promote Carbon Dioxide‐to‐Methanol Conversion.

Author

Zhang, Xibo, Yu, Xiang, Mendes, Rafael G., Matvija, Peter, Melcherts, Angela E. M., Sun, Chunning, Ye, Xinwei, Weckhuysen, Bert M., and Monai, Matteo

Abstract

ZnO/ZrO2 catalysts have shown better activity in the CO2 hydrogenation to methanol compared with single component counterparts, but the interaction between ZnO and ZrO2 is still poorly understood. In particular, the effect of the ZrO2 support phase (tetragonal vs. monoclinic) was not systematically explored. Here, we have synthesized ZnO/ZrO2 catalysts supported on tetragonal ZrO2 (ZnO/ZrO2‐t) and monoclinic ZrO2 (ZnO/ZrO2‐m), which resulted in the formation of different ZnOx species, consisting of sub‐nanometer ZnO moieties and large‐sized ZnO particles, respectively. ZnO/ZrO2‐t exhibited a higher methanol selectivity (81 vs. 39 %) and methanol yield (1.25 vs. 0.67 mmol g−1 h−1) compared with ZnO/ZrO2‐m. The difference in performance was attributed to the redox state and degree of dispersion of Zn, based on spectroscopy and microscopy results. ZnO/ZrO2‐t had a high density of ZnOx‐ZrOy sites, which favored the formation of active HCOO* species and enhanced the yield and selectivity of methanol along the formate pathway. Such ZnO clusters were further dispersed on ZrO2‐t during catalysis, while larger ZnO particles on ZnO/ZrO2‐m remained stable throughout the reaction. This study shows that the phase of ZrO2 supports can be used to control the dispersion of ZnO and the catalyst surface chemistry, and lead to enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Published
2024
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38. Photosensitive Field‐Effect Transistors Made from Semiconducting Carbon Nanotubes and Non‐Covalently Attached Gold Nanoparticles

Author

Blaudeck, Thomas, primary, Preuß, Andrea, additional, Scharf, Sebastian, additional, Notz, Sebastian, additional, Kossmann, Alexander, additional, Hartmann, Susanne, additional, Kasper, Laura, additional, Mendes, Rafael G., additional, Gemming, Thomas, additional, Hermann, Sascha, additional, Lang, Heinrich, additional, and Schulz, Stefan E., additional

Published
2019
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39. Molecular Scaffold Growth of Two-Dimensional, Strong Interlayer-Bonding-Layered Materials

Author

Zeng, Mengqi, primary, Chen, Yunxu, additional, Zhang, Enze, additional, Li, Jiaxu, additional, Mendes, Rafael G., additional, Sang, Xiahan, additional, Luo, Shulin, additional, Ming, Wenmei, additional, Fu, Yuhao, additional, Du, Mao-Hua, additional, Zhang, Lijun, additional, Parker, David S., additional, Unocic, Raymond R., additional, Xiao, Kai, additional, Wang, Chenglai, additional, Zhang, Tao, additional, Xiao, Yao, additional, Rümmeli, Mark H., additional, Xiu, Faxian, additional, and Fu, Lei, additional

Published
2019
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40. Low pressure chemical vapor deposition synthesis of large area hetero-doped mono- and few- layer graphene with nitrogen and oxygen species

Author

Hasan, Maria, primary, Meiou, Wang, additional, Yulian, Liu, additional, Ta, Huy Q, additional, Zhao, Liang, additional, Mendes, Rafael G, additional, Oswald, Stefan, additional, Akhter, Zareen, additional, Malik, Zahida P, additional, Ahmad, Nasir M, additional, Liu, Zhongfan, additional, and Rümmeli, Mark H, additional

Published
2019
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46. Tailoring the stoichiometry of C3N4 nanosheets under electron beam irradiation.

Author

Mendes, Rafael G., Ta, Huy Q., Yang, Xiaoqin, Bachmatiuk, Alicja, Praus, Petr, Mamakhel, Aref, Iversen, Bo B., Su, Ren, Gemming, Thomas, and Rümmeli, Mark H.

Abstract

Two-dimensional polymeric graphitic carbon nitride (g-C3N4) is a low-cost material with versatile properties that can be enhanced by the introduction of dopant atoms and by changing the degree of polymerization/stoichiometry, which offers significant benefits for numerous applications. Herein, we investigate the stability of g-C3N4 under electron beam irradiation inside a transmission electron microscope operating at different electron acceleration voltages. Our findings indicate that the degradation of g-C3N4 occurs with N species preferentially removed over C species. However, the precise nitrogen group from which N is removed from g-C3N4 (C–N–C, ＝NH or –NH2) is unclear. Moreover, the rate of degradation increases with decreasing electron acceleration voltage, suggesting that inelastic scattering events (radiolysis) dominate over elastic events (knock-on damage). The rate of degradation by removing N atoms is also sensitive to the current density. Hence, we demonstrate that both the electron acceleration voltage and the current density are parameters with which one can use to control the stoichiometry. Moreover, as N species were preferentially removed, the d-spacing of the carbon nitride structure increased. These findings provide a deeper understanding of g-C3N4. [ABSTRACT FROM AUTHOR]

Published
2021
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47. A comparative study on simple and practical chemical gas sensors from chemically modified graphene films

Author

Wrobel, Pawel S, primary, Wlodarski, Michal D, additional, Jedrzejewska, Anna, additional, Placek, Krzysztof M, additional, Szukiewicz, Rafal, additional, Kotowicz, Sonia, additional, Tokarska, Klaudia, additional, Quang, Huy Ta, additional, Mendes, Rafael G, additional, Liu, Zhongfan, additional, Trzebicka, Barbara, additional, Rummeli, Mark H, additional, and Bachmatiuk, Alicja, additional

Published
2018
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