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Monochromatic X-Ray Induced Novel Synthesis of Plasmonic Nanostructure for Photovoltaic Application.

Bharti A, Bhardwaj R, Agrawal AK, Goyal N, Gautam S - Sci Rep (2016)

Bottom Line: It has been universally delineated that the plasmonic metal nanoparticles can enhance the efficiency of photovoltaic cell by increasing the probability of energetic solar photons capturing phenomena using localized surface plasmonic resonance response.X-ray radiolysis based synthesis provides the control over the reaction and prevent the formation of secondary products as occurs in case of chemical reduction route.In the previous studies, synchrotron "white" X-rays had been examined for the synthesis of metal nanoparticles, but that technique limits only upto the material synthesis while in this work we explored the role of "monochromatic" X-rays for the production of bulk amount of nanoparticles which would also provide the feasibility of in-situ characterization.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Panjab University, Chandigarh-160014, INDIA.

ABSTRACT
It has been universally delineated that the plasmonic metal nanoparticles can enhance the efficiency of photovoltaic cell by increasing the probability of energetic solar photons capturing phenomena using localized surface plasmonic resonance response. In this paper, we developed a novel in-situ simple approach to synthesize noble plasmonic silver nanoparticles (AgNP) from aqueous poly-vinyl-pyrrolidone solution of metal salt using radiolysis of water via synchrotron monochromatic X-ray irradiation without any chemical reducing agent. X-ray irradiation of water produces hydrated electrons (e(-)aq), superoxide (O(-)2) and atom radicals H*, which triggers the reaction and reduces metal salt. X-ray radiolysis based synthesis provides the control over the reaction and prevent the formation of secondary products as occurs in case of chemical reduction route. In the previous studies, synchrotron "white" X-rays had been examined for the synthesis of metal nanoparticles, but that technique limits only upto the material synthesis while in this work we explored the role of "monochromatic" X-rays for the production of bulk amount of nanoparticles which would also provide the feasibility of in-situ characterization. Transmission electron micrographs show that the synthesized AgNP appears spherical with diameter of 2-6 nm and is in agreement with the size estimation from uv-vis spectra by "Mie theory".

No MeSH data available.


Related in: MedlinePlus

Transmission electron micrographs of sample A5 (a), repeated after 25 days (b), and similarly sample d1 is shown in (c,d) respectively along with their size histogram.
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f4: Transmission electron micrographs of sample A5 (a), repeated after 25 days (b), and similarly sample d1 is shown in (c,d) respectively along with their size histogram.

Mentions: In the previous studies, isopropanol or ethanol had been introduced as a scavenger to avoid the oxidation of metal nanoparticles13. In our study, we have performed the experiment with and without the presence of this scavenger and investigate the actual mechnism. We did not observe any oxidation, which might be due to the presence of PVP that has enough capability to cap the particles and prevent them from the oxidation. Hence the presence of isopropanol/ethanol not only scavenges from oxidation, but also produces the reducing agent which reduce the size of nanoparticles. The centroid (peak-position) and the broadening (FWHM) of UV-vis spectra of AgNP depend upon the particle size, shape, and surface charge28. We have fitted/simulated the data according to the extended version of “Mie-Theory”28 to estimate the size of nanoparticles so formed. According to Mie-theory, particle size of samples d1 and A5 with absorption centroid at 422 and 406 nm, band width of 135.48 and 105.17 nm comes out to be 2.69 and 4.16 nm respectively (Table 1). Figure 4 shows the TEM micrographs of both the samples along-with the histograms. TEM micrographs were investigated by the imageJ package and data is fitted using Gaussian function. The calculated average size of NP for the sample d1 and A5 are 3.61 and 4.00 nm respectively. The histogram shows that the maximum intensity of the nanoparticles present in the solution is in agreement with the size estimation by extended version of Mie-theory (Table 1). To further check the self-lifetime of synthesized plasmonic nanoparticles, TEM measurements were repeated after the time span of 25 days and it is clear that there is no coagulation of nanoparticles as shown in Fig. 4. Synthesized nanoparticles have ultrahigh stability and retain the same size and shape profile as of freshly synthesized even after the age of 68 days (Table 1), as shown in the Fig. 5. A small decrement as observed in the average particle size is because of centrifugation of the samples, result in the highly concentrated product sample (clearly revealed in Fig. 4) and lead to collect the smaller particles also by TEM. In addition to this, the role of X-ray energy has been investigated by exposing the sample to different energies at constant irradiation dose. As the X-ray energy increases, the sample becomes more transparent to corresponding beam resulting in loss of irradiation dose. So the energy-time product has been set to keep the irradiation dose constant. Figure 6 shows the UV-Vis spectra of samples irradiated at different energies reveals that high X-ray energy produces the “hot” hydrated electron (although the dose is constant), which reduces the metal salt with inflate speed resulting in enhancement of particle size. The process of generation of “hot” is dependent on X-rays energy, flux and sample holder size. The particle size and concentration is of utmost level at 20 keV in case of our sample holder dimensions. If, one selects a very thin sample holder then even low energy X-rays could lead to the formation of metallic nanoparticles.


Monochromatic X-Ray Induced Novel Synthesis of Plasmonic Nanostructure for Photovoltaic Application.

Bharti A, Bhardwaj R, Agrawal AK, Goyal N, Gautam S - Sci Rep (2016)

Transmission electron micrographs of sample A5 (a), repeated after 25 days (b), and similarly sample d1 is shown in (c,d) respectively along with their size histogram.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837342&req=5

f4: Transmission electron micrographs of sample A5 (a), repeated after 25 days (b), and similarly sample d1 is shown in (c,d) respectively along with their size histogram.
Mentions: In the previous studies, isopropanol or ethanol had been introduced as a scavenger to avoid the oxidation of metal nanoparticles13. In our study, we have performed the experiment with and without the presence of this scavenger and investigate the actual mechnism. We did not observe any oxidation, which might be due to the presence of PVP that has enough capability to cap the particles and prevent them from the oxidation. Hence the presence of isopropanol/ethanol not only scavenges from oxidation, but also produces the reducing agent which reduce the size of nanoparticles. The centroid (peak-position) and the broadening (FWHM) of UV-vis spectra of AgNP depend upon the particle size, shape, and surface charge28. We have fitted/simulated the data according to the extended version of “Mie-Theory”28 to estimate the size of nanoparticles so formed. According to Mie-theory, particle size of samples d1 and A5 with absorption centroid at 422 and 406 nm, band width of 135.48 and 105.17 nm comes out to be 2.69 and 4.16 nm respectively (Table 1). Figure 4 shows the TEM micrographs of both the samples along-with the histograms. TEM micrographs were investigated by the imageJ package and data is fitted using Gaussian function. The calculated average size of NP for the sample d1 and A5 are 3.61 and 4.00 nm respectively. The histogram shows that the maximum intensity of the nanoparticles present in the solution is in agreement with the size estimation by extended version of Mie-theory (Table 1). To further check the self-lifetime of synthesized plasmonic nanoparticles, TEM measurements were repeated after the time span of 25 days and it is clear that there is no coagulation of nanoparticles as shown in Fig. 4. Synthesized nanoparticles have ultrahigh stability and retain the same size and shape profile as of freshly synthesized even after the age of 68 days (Table 1), as shown in the Fig. 5. A small decrement as observed in the average particle size is because of centrifugation of the samples, result in the highly concentrated product sample (clearly revealed in Fig. 4) and lead to collect the smaller particles also by TEM. In addition to this, the role of X-ray energy has been investigated by exposing the sample to different energies at constant irradiation dose. As the X-ray energy increases, the sample becomes more transparent to corresponding beam resulting in loss of irradiation dose. So the energy-time product has been set to keep the irradiation dose constant. Figure 6 shows the UV-Vis spectra of samples irradiated at different energies reveals that high X-ray energy produces the “hot” hydrated electron (although the dose is constant), which reduces the metal salt with inflate speed resulting in enhancement of particle size. The process of generation of “hot” is dependent on X-rays energy, flux and sample holder size. The particle size and concentration is of utmost level at 20 keV in case of our sample holder dimensions. If, one selects a very thin sample holder then even low energy X-rays could lead to the formation of metallic nanoparticles.

Bottom Line: It has been universally delineated that the plasmonic metal nanoparticles can enhance the efficiency of photovoltaic cell by increasing the probability of energetic solar photons capturing phenomena using localized surface plasmonic resonance response.X-ray radiolysis based synthesis provides the control over the reaction and prevent the formation of secondary products as occurs in case of chemical reduction route.In the previous studies, synchrotron "white" X-rays had been examined for the synthesis of metal nanoparticles, but that technique limits only upto the material synthesis while in this work we explored the role of "monochromatic" X-rays for the production of bulk amount of nanoparticles which would also provide the feasibility of in-situ characterization.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Panjab University, Chandigarh-160014, INDIA.

ABSTRACT
It has been universally delineated that the plasmonic metal nanoparticles can enhance the efficiency of photovoltaic cell by increasing the probability of energetic solar photons capturing phenomena using localized surface plasmonic resonance response. In this paper, we developed a novel in-situ simple approach to synthesize noble plasmonic silver nanoparticles (AgNP) from aqueous poly-vinyl-pyrrolidone solution of metal salt using radiolysis of water via synchrotron monochromatic X-ray irradiation without any chemical reducing agent. X-ray irradiation of water produces hydrated electrons (e(-)aq), superoxide (O(-)2) and atom radicals H*, which triggers the reaction and reduces metal salt. X-ray radiolysis based synthesis provides the control over the reaction and prevent the formation of secondary products as occurs in case of chemical reduction route. In the previous studies, synchrotron "white" X-rays had been examined for the synthesis of metal nanoparticles, but that technique limits only upto the material synthesis while in this work we explored the role of "monochromatic" X-rays for the production of bulk amount of nanoparticles which would also provide the feasibility of in-situ characterization. Transmission electron micrographs show that the synthesized AgNP appears spherical with diameter of 2-6 nm and is in agreement with the size estimation from uv-vis spectra by "Mie theory".

No MeSH data available.


Related in: MedlinePlus