Kelvin probe force microscopic investigation of graphene-based derivatives

Silva, K. Kanishka H. De; Ogawa, S.; Viswanath, Pamarti; Yoshimura, Masamichi

doi:10.35848/1347-4065/ab7fe3

Cited by 6 publications

(4 citation statements)

References 29 publications

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“…These results reveal that the systematic change in the CPD value and the corresponding work function depends on the composition and structure of the carbon carrier and the type of doped atoms. The measurement result of the GO work function is approximately 4.85 eV, and the work function of rGO was 4.70 eV, which is consistent with the trend reported previously. , Compared with GO, the decrease in the rGO work function and the increase in CPD may be due to the removal of oxygen functional groups and the improvement of electron conductivity on the rGO sheet. , However, the work function values of graphene-based catalysts are shown in the following order: GO (4.85 eV) > GO-N (4.35 eV) > GO-Fe–N (4.07 eV) and rGO (4.70 eV) > rGO-N (4.46 eV) > rGO-Fe–N (4.19 eV). The results indicate that the doping of heteroatoms (such as N and Fe atoms) will reduce the work function of the catalyst.…”

Section: Resultsmentioning

confidence: 99%

Insights into the Determining Effect of Carbon Support Properties on Anchoring Active Sites in Fe–N–C Catalysts toward the Oxygen Reduction Reaction

Zheng

et al. 2022

ACS Catal.

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As one of the most promising non-noble metal electrocatalysts for the oxygen reduction reaction (ORR), previous investigations on Fe–N–C materials have mainly focused on the innovation of synthetic methods, identification of active sites, and structure optimization, but the intrinsic properties of carbon supports used to anchor Fe–N x active sites have often been neglected. Herein, graphene oxide (GO) and reduced GO (rGO) are used as support models for heteroatom doping to prepare Fe–N–C catalysts. The obvious and easily distinguishable defects and the content of oxygen-containing functional groups in GO and rGO directly determined the doping content, structure type, and coordination environment of N and Fe. Notably, through analysis of the surface potential as a common parameter measured by Kelvin probe force microscopy, local work functions of these graphene-based catalysts at the nanoscale and their statistical averages were used to study the distribution of active sites and their association with ORR kinetics. This insight into the influence of carbon support structure properties on active sites and the work function–ORR performance relationship may provide guidance for exploring the origin of ORR activity and designing better non-noble metal electrocatalysts.

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Section: Resultsmentioning

confidence: 99%

Insights into the Determining Effect of Carbon Support Properties on Anchoring Active Sites in Fe–N–C Catalysts toward the Oxygen Reduction Reaction

Zheng

et al. 2022

ACS Catal.

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“…With the discovery and the development of graphene, graphene oxide (GO) and its reduced counterpart (reduced GORGO) has been regarded as the most promising precursors for pristine graphene because they can be scaled up to industrial requirement with controllable properties. , However, the lattice structure of GO is more complex than graphene obtained via mechanical exfoliation or chemical vapor deposition (CVD) due to the abundant defects, including oxygen-containing groups and lattice vacancies. This results in different chemical and physical properties in GO and RGO. − On the other hand, RGO has properties that lie between GO and graphene. As a result, the interpretation of Raman spectra of GO and RGO is more complicated than that of other carbon nanomaterials .…”

Section: Introductionmentioning

confidence: 99%

New Insight into the Characterization of Graphene Oxide and Reduced Graphene Oxide Monolayer Flakes on Si-Based Substrates by Optical Microscopy and Raman Spectroscopy

et al. 2021

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Graphene oxide (GO) and reduced GO (RGO) have attracted interest as economical alternatives for pristine graphene with controllable properties spanning their applications in many fields. Abundant lattice defects present in GO and RGO have made their physical and chemical properties largely diverse from that of pristine graphene. This makes their identification and characterization ambiguous as the rules applied for pristine graphene may not be practical for GO and RGO. Here, we report a new insight into the characterization of GO and thermally reduced GO monolayer flakes deposited on different commonly used Si-based substrates by Raman spectroscopy along with optical visualization to address this uncertainty. It was found that the dielectric substrates with a lower reflectance in the visible range give a better optical contrast under normal white light illumination and intense Raman signals owing to the multiple reflection and interference at the interfaces of the multilayer system. Accordingly, a Si substrate with a 90 nm SiO2 layer gives the highest I G′/I G ratio along with a better optical visibility for monolayer RGO flakes.

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“…In contrast to ME, epitaxial, and CVD-graphene, GO and RGO have many kinds of defects that could drastically change the surface potential, particularly due to the difference in charge transfer effect associated with the oxygen-containing functional groups [83,85,86]. By carrying out a systematic study on the dependence of WF on the oxygen content of GO during chemical reduction, Mishra et al have reported that the CPD value decreases (WF increases) with the removal of oxygen functionalities from GO (reduction of GO) [78].…”

Section: Surface Potential Of Graphene Oxide (Go) and Reduced Graphen...mentioning

confidence: 99%

Nanoscale electrical characterization of graphene-based materials by atomic force microscopy

Silva

Huang

Viswanath

et al. 2022

Journal of Materials Research

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Graphene, an atomically thin two-dimensional (2D) material, exhibits outstanding electrical properties and thus has been employed in various electronic devices. However, the device performance strongly depends on the structural variations present in the graphitic lattice, such as crystal domains, grain boundaries, lattice imperfections, dopants, etc., which are nanoscopic in nature. Hence, understanding the correlation between the structure and the electrical properties in the nanoscale is essential. Atomic force microscopy (AFM) techniques provide the best way to picture such relationships, which is particularly in demand for future miniaturized devices. This review article highlights the characterization of the electrical properties of graphene-based materials via AFM-based techniques such as conductive AFM, scanning Kelvin probe microscopy, electrostatic force microscopy, and piezoresponse force microscopy that is certainly beneficial for a broad research community not only working on graphene-based materials but also in the fields of other 2D materials and scanning probe microscopy. Graphical abstract

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Kelvin probe force microscopic investigation of graphene-based derivatives

Cited by 6 publications

References 29 publications

Insights into the Determining Effect of Carbon Support Properties on Anchoring Active Sites in Fe–N–C Catalysts toward the Oxygen Reduction Reaction

Insights into the Determining Effect of Carbon Support Properties on Anchoring Active Sites in Fe–N–C Catalysts toward the Oxygen Reduction Reaction

New Insight into the Characterization of Graphene Oxide and Reduced Graphene Oxide Monolayer Flakes on Si-Based Substrates by Optical Microscopy and Raman Spectroscopy

Nanoscale electrical characterization of graphene-based materials by atomic force microscopy

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