Tag: atomic force microscopy

In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface

“Methanol occupies a central role in chemical synthesis and is considered an ideal candidate for cleaner fuel storage and transportation. It can be catalyzed from water and volatile organic compounds, such as carbon dioxide, thereby offering an attractive solution for reducing carbon emissions.”*

In “In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface” the authors show that graphite immersed in ultrapure water is able to spontaneously catalyze methanol from volatile organic compounds in ambient conditions. Using single-molecule resolution atomic force microscopy (AFM) in liquid, they directly observe the formation and evolution of methanol–water nanostructures at the surface of graphite.*
The findings described in this article could have a significant impact on the development of organic catalysts and on the function of nanoscale carbon devices

NanoWorld ARROW-UHFAuD AFM probes were used for the Atomic Force Microscopy imaging in liquid.

Figure 1 from “In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface” by W. Foster et al.: High-resolution amplitude modulation AFM imaging of HOPG immersed in initially ultrapure water. (a) A solid-like patch formed by the self-assembly of molecules (dashed white outline) nucleates from an atomic step at the HOPG surface (dashed black line). The molecular self-assembly is observed here in situ as it progressively grows across the HOPG surface over a period of 9 min, with the patch edges moving away from the step. Rowlike structures with a periodicity of 4.30 ± 0.28 nm as visible within the patch. (b) Sub-nanometer imaging of other structures reveals detailed features (0.79 ± 0.08 nm periodicity, red arrows) perpendicular to the main rows (periodicity 2.45 ± 0.08 nm, white arrow). The exact molecular arrangement is not known, but strongly reminiscent of the alternated water–methanol nanoribbons recently reported by our group.(22) The white scale bars are 100 nm in (a) and 1 nm in (b). The purple color scale bar represents a topographic variation of 20 Å in (a) and 1 Å nm in (b). The blue scale bar represents a phase variation of 20° in (a) and 10° in (b). In (a) the time lapse between the first and second frames is 1 min and then 4 min elapses between the subsequent frames. NanoWorld Arrow-UHFAuD AFM probes were used.
Figure 1 from “In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface” by W. Foster et al.: High-resolution amplitude modulation AFM imaging of HOPG immersed in initially ultrapure water. (a) A solid-like patch formed by the self-assembly of molecules (dashed white outline) nucleates from an atomic step at the HOPG surface (dashed black line). The molecular self-assembly is observed here in situ as it progressively grows across the HOPG surface over a period of 9 min, with the patch edges moving away from the step. Rowlike structures with a periodicity of 4.30 ± 0.28 nm as visible within the patch. (b) Sub-nanometer imaging of other structures reveals detailed features (0.79 ± 0.08 nm periodicity, red arrows) perpendicular to the main rows (periodicity 2.45 ± 0.08 nm, white arrow). The exact molecular arrangement is not known, but strongly reminiscent of the alternated water–methanol nanoribbons recently reported by our group.(22) The white scale bars are 100 nm in (a) and 1 nm in (b). The purple color scale bar represents a topographic variation of 20 Å in (a) and 1 Å nm in (b). The blue scale bar represents a phase variation of 20° in (a) and 10° in (b). In (a) the time lapse between the first and second frames is 1 min and then 4 min elapses between the subsequent frames

*William Foster, Juan A. Aguilar, Halim Kusumaatmaja, Kislon Voϊtchovsky
In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface
ACS Appl. Mater. Interfaces, 2018, 10 (40), pp 34265–34271
DOI: 10.1021/acsami.8b12113

Please follow this external link for the full article: https://pubs.acs.org/doi/full/10.1021/acsami.8b12113

Open Access The article “In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface” by William Foster, Juan A. Aguilar, Halim Kusumaatmaja and Kislon Voϊtchovsky is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM

In the article «Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” Yanlong Li, Chuanhui Chen, John Burton, Kyungwha Park, James R Heflin and Chenggang Tao demonstrate that PCBM molecules self-assemble into bilayer structures on graphene and HOPG substrates. They used Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM), and analyzed the observed morphology by comparison to molecular models.*

The AFM measurements were carried out in a dark environment. NanoWorld™ Pointprobe® NCST AFM probes were used in soft tapping mode and simultaneous height and phase images were acquired and reproduced across multiple samples.*

The results of this study shed light on improvement of the energy efficiency in solar cells containing graphene and organic molecules, by increasing the donor–acceptor interface area and could provide valuable insight into fabrication of new hybrid, ordered structures for applications to organic solar cells.*

Figure 5. from “Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” by Yanlong Li et al.: AFM images of PCBM bilayer and size distributions of holes at different conditions. (a) AFM image of a PCBM bilayer before annealing. (b) AFM image of a PCBM bilayer after annealing at 140 °C. (c) AFM image of a PCBM bilayer after annealing at 160 °C. (d) Area distribution histogram of holes (without PCBM area) obtained from measurements of the area of holes in AFM images of before (green) and after annealing at 140 °C (dark red) and 160 °C (dark blue). Monolithic silicon cantilevers (NCST, NANO WORLD) with a spring constant of 7.4 N m−1, first longitudinal resonance frequencies between 120 and 205 kHz, and nominal tip radius of 8 nm were employed in soft tapping mode. Simultaneous height and phase images were acquired and reproduced across multiple samples.
Figure 5. from “Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” by Yanlong Li et al.: AFM images of PCBM bilayer and size distributions of holes at different conditions. (a) AFM image of a PCBM bilayer before annealing. (b) AFM image of a PCBM bilayer after annealing at 140 °C. (c) AFM image of a PCBM bilayer after annealing at 160 °C. (d) Area distribution histogram of holes (without PCBM area) obtained from measurements of the area of holes in AFM images of before (green) and after annealing at 140 °C (dark red) and 160 °C (dark blue).

*Yanlong Li, Chuanhui Chen, John Burton, Kyungwha Park, James R Heflin, Chenggang Tao
Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM
Nanotechnology, Volume 29, Number 18 (2018)
DOI: https://doi.org/10.1088/1361-6528/aab00a

Open Access The article “Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” by Yanlong Li et al. is licensed under a Creative Commons Attribution 3.0 International License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. To view a copy of this license, visit https://creativecommons.org/licenses/by/3.0/

Ferroelectric domains and phase transition of sol-gel processed epitaxial Sm-doped BiFeO3 (001) thin films

Read how Nanoworld Arrow-EFM AFM probes were used in the paper “Ferroelectric domains and phase transition of sol-gel processed epitaxial Sm-doped BiFeO3 (001) thin films” in which the authors Zhen Zhou, Wie Sun, Zhenyu Liao, Shuai Ning, Jing Zhu and Jing-Feng Li:

  • prepared 12% Sm-doped BiFeO3 epitaxial thin films on Nb-doped SrTiO3 (001) substrate via a sol-gel method
  • used PFM (piezoresponse force microscopy) to characterize the in-situ ferroelectric domain evolution from room temperature to 200 °C
  • illustrated a phase transition from ferroelectric to antiferroelectric phase by SS-PFM and found a significant piezoelectric response at the phase boundary

Their work revealed the origin of the high piezoresponse of Sm-doped BiFeO3 thin films at the morphotropic phase boundary (MPB).*

A PtIr-coated NanoWorld Arrow-EFM cantilever with a nominal spring constant of 2.8 N/m and a typical resonant frequency of 75 kHz was used in all imaging modes mentioned in the article.

Figure 3 from “Ferroelectric domains and phase transition of sol-gel processed epitaxial Sm-doped BiFeO3 (001) thin films” by Zhen Zhou et al. : PFM scanning results of the sample at 20 °C, 80 °C, 140 °C and 200 °C, (a)-(d) out-of-plane phase, (e)-(h) out-of-plane amplitude, (i)-(l) in-plane phase, and (m)-(p) in-plane amplitude. NanoWorld Arrow-EFM AFM probes were used in all imaging modes.
Figure 3 from “Ferroelectric domains and phase transition of sol-gel processed epitaxial Sm-doped BiFeO3 (001) thin films” by Zhen Zhou et al. : PFM scanning results of the sample at 20 °C, 80 °C, 140 °C and 200 °C, (a)-(d) out-of-plane phase, (e)-(h) out-of-plane amplitude, (i)-(l) in-plane phase, and (m)-(p) in-plane amplitude.

 
 
 
 
 
 
             
*Zhen Zhou, Wie Sun, Zhenyu Liao, Shuai Ning, Jing Zhu, Jing-Feng Li
Ferroelectric domains and phase transition of sol-gel processed epitaxial Sm-doped BiFeO3 (001) thin films

Journal of Materiomics, Volume 4, Issue 1, March 2018, Pages 27-34
DOI: https://doi.org/10.1016/j.jmat.2017.11.002

Please follow this external link if you would like to read the full article: https://www.sciencedirect.com/science/article/pii/S2352847817300631

Open Access The article “Ferroelectric domains and phase transition of sol-gel processed epitaxial Sm-doped BiFeO3 (001) thin films” by Zhen Zhou, Wie Sun, Zhenyu Liao, Shuai Ning, Jing Zhu and Jing-Feng Li is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.