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http://hdl.handle.net/2289/7567
Title: | Ni Nanoparticles Coated with Nitrogen-Doped Carbon for Optical Limiting Applications |
Authors: | Kumar, Rajeev Kumar, Ajay Verma, Nancy Philip, Reji +2 Co-Authors |
Keywords: | pyrolysis carbon nanostructures graphite-encapsulated Ni nanoparticles nonlinear optical absorption (NLA) free carrier absorption (FCA) optical limiter |
Issue Date: | Sep-2020 |
Publisher: | American Chemical Society |
Citation: | ACS Applied Nano Materials, 2020, Vol.3, p8618–8631 |
Abstract: | In this work, we demonstrate the importance of the free carrier absorption (FCA) process in the nonlinear optical absorption (NLA) behavior of carbonaceous nanomaterials synthesized by pyrolysis at different heating rates (Rh = 1, 3, 10, and 20 °C/min). The chemical vapor deposition reaction through the pyrolysis of Ni(II) acetylacetonate, melamine, and toluene precursors was carried out at 600 °C, which leads to different carbonaceous nanostructures embedded with graphite-encapsulated Ni nanoparticles (Ni@C samples). A lower Rh (1 and 3 °C/min) value leads to the formation of globular carbon aggregates embedded with core–shell-type Ni–graphite nanoparticles, whereas a high Rh (10 and 20 °C/min) value leads to the formation of carbon nanotubes embedded with similar Ni–graphite core–shell nanoparticles. The samples prepared at moderate heating rates of 3 and 10 °C/min show prominently high NLA than those prepared at very slow or very fast (1 and 20 °C/min) heating rates. According to our results, the quality (and the amount) of graphitization and nitrogen defect centers enhance the NLA behavior of the Ni@C samples. This result is obtained through the enhancement of excited-state absorption (ESA) behavior of the samples due to the introduction of defect states within the band gap of the graphite layer. More importantly, the metallic Ni nanoparticles help in drastically enhancing the NLA through the FCA process. To prove this supposition, we demonstrated that the presence of any dielectric phase (e.g., NiO) within the metallic nanoparticles (or within the sample) acts as a barrier to FCA, thereby reducing the NLA. Our work highlights the importance of synthesis conditions (optimized heating rate), especially in controlling the quality of graphitization and the embedded metallic Ni particles in the Ni@C samples in enhancing the NLA. Furthermore, through the mechanistic insights, we emphasized the potential use of our Ni@C samples for optical limiting applications because of their excellent NLA behavior originating through the FCA and ESA processes. |
Description: | Restricted Access |
URI: | http://hdl.handle.net/2289/7567 |
ISSN: | 2574-0970 |
Alternative Location: | https://doi.org/10.1021/acsanm.0c01284 |
Copyright: | 2020 American Chemical Society |
Appears in Collections: | Research Papers (LAMP) |
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2020_ACS Applied Nano Materials_Vol.3_p8618-8631.pdf Restricted Access | Restricted Access | 9.13 MB | Adobe PDF | View/Open Request a copy |
2020_ACS Applied Nano Materials_Vol.3_p8618-8631.Support Informationpdf.pdf | Open Access | 1.27 MB | Adobe PDF | View/Open |
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