DESC:DETAILED DESCRIPTION OF THE INVENTION
Some embodiments of the present disclosure, illustrating all its features, will now
be discussed in detail. It must also be noted that as used herein and in the
appended claims, the singular forms "a", "an" and "the" include plural references
15 unless the context clearly dictates otherwise.
Various modifications to the embodiment will be readily apparent to those skilled
in the art and the generic principles herein may be applied to other embodiments.
However, one of ordinary skill in the art will readily recognize that the present
20 disclosure including the definitions listed here below are not intended to be
limited to the embodiments illustrated but is to be accorded the widest scope
consistent with the principles and features described herein.
A person of ordinary skill in the art will readily ascertain that the illustrated steps
detailed in the figures and here below are set out to explain the exemplary
25 embodiments shown, and it should be anticipated that ongoing technological
development will change the manner in which particular functions are
7
performed. These examples are presented herein for purposes of illustration, and
not limitation. Further, the boundaries of the functional building blocks have
been arbitrarily defined herein for the convenience of the description. Alternative
boundaries can be defined so long as the specified functions and relationships
thereof are appropriately 5 performed. Alternatives (including equivalents,
extensions, variations, deviations, etc., of those described herein) will be apparent
to persons skilled in the relevant art(s) based on the teachings contained herein.
Such alternatives fall within the scope and spirit of the disclosed embodiments.
Before discussing example, embodiments in more detail, it is to be noted that the
10 drawings are to be regarded as being schematic representations and elements that
are not necessarily shown to scale. Rather, the various elements are represented
such that their function and general purpose becomes apparent to a person
skilled in the art. Any connection or coupling between functional blocks, devices,
components, or other physical or functional units shown in the drawings or
15 described herein may also be implemented by an indirect connection or coupling.
A coupling between components may also be established over a wireless
connection. Functional blocks may be implemented in hardware, firmware,
software or a combination thereof.
Further, the flowcharts provided herein, describe the operations as sequential
20 processes. Many of the operations may be performed in parallel, concurrently or
simultaneously. In addition, the order of operations maybe re-arranged. The
processes may be terminated when their operations are completed but may also
have additional steps not included in the figured. It should be noted, that in some
alternative implementations, the functions/acts/ steps noted may occur out of
25 the order noted in the figured. For example, two figures shown in succession may,
in fact, be executed substantially concurrently, or may sometimes be executed in
the reverse order, depending upon the functionality/acts involved.
8
Further, the terms first, second etc… may be used herein to describe various
elements, components, regions, layers and/or sections, these elements,
components, regions, layers and/or sections should not be limited by these terms.
These terms are used only to distinguish one element, component, region, layer
or section from another region, layer, or a 5 section. Thus, a first element,
component, region layer, or section discussed below could be termed a second
element, component, region, layer, or section without departing form the scope
of the example embodiments.
The terminology used herein is for the purpose of describing example
10 embodiments only and is not intended to be limiting. Unless otherwise defined,
all terms (including technical and scientific terms) used herein have the same
meaning as commonly understood by one of ordinary skill in the art to which
example embodiments belong. It will be further understood that terms, e.g., those
defined in commonly used dictionaries, should be interpreted as having a
15 meaning that is consistent with their meaning in the context of the relevant art
and will not be interpreted in an idealized or overly formal sense unless expressly
so defined herein.
As used herein, the singular forms “a,” “an,” and “the,” are intended to include
the plural forms as well, unless the context clearly indicates otherwise. As used
20 herein, the terms “and/or” and “at least one of” include any and all combinations
of one or more of the associated listed items. It will be further understood that the
terms “comprises,” “comprising,” “includes,” and/or “including,” when used
herein, specify the presence of stated features, integers, steps, operations,
elements, and/or components, but do not preclude the presence or addition of
25 one or more other features, integers, steps, operations, elements, components,
and/or groups thereof.
9
The present invention discloses a breakthrough method for CQD synthesis by
harnessing concentrated solar or laser energy in a novel, mirror-lined chamber,
enabling green, scalable, and high-yield production with broad industrial
applicability.
The invention is the integration of optical engineering 5 (focused solar or laser
energy) with a specially designed, energy-efficient reaction chamber for the
green, scalable, and targeted synthesis of high-quality carbon quantum dots from
plant-based materials. Said method is energy-efficient, environmentally friendly,
cost-effective and have versatile for various applications and energy sources.
10
The present invention discloses a method for synthesizing carbon quantum dot
(CQD), wherein said method comprising the steps of providing a reaction chamber
having metallic, double-wall insulation and internal mirrors arranged for total
internal reflection; introducing a solution comprising plant-based extracts
15 dissolved in a volatile solvent into the reaction chamber; concentrating energy
source onto the solution within the reaction chamber with or without the a convex
lens, heating the solution and initiating the formation of CQDs; maintaining the
solution under concentrated energy source for a period sufficient to form CQDs;
and recovering the synthesized CQDs.
20
Various types of energy sources can be utilized for synthesis of CQDs such as
solar energy or in case sunlight is not present then other types of energy can be
utilized for synthesis of CQDs.
Sunlight is focused using a convex lens of focal length 5mm is used to make rays
25 convergent to a point, and then, this is again passed through a convex lens of
same focal length. This entering into the chamber undergoes multiple reflections
and concentrates on the central quartz cuvette (10mm path length, 3.5mL
volume). The highly volatile solvents, specifically 95% pure Methanol (M),
10
Acetone (A), and Ethanol (E), are utilized in quartz cuvettes. The concentration
of these solvents used is in the range of 95% purity. Precursor materials are
dissolved in these solvents at a concentration of 0.5 mg/mL and subsequently
drop-casted. This is a bottom-up synthesis procedure, where precursor material
used is Tacoma Stans plant leaf extract, with different 5 solvents, such as ethanol,
methanol and acetone and this is then drop casted on a TLC plate and in an A4
sheet paper, the solvent casted on A4 sheet paper got dissolved into the cuvette
solution by itself, as cellulose containing paper got degraded faster due to the
concentrated heat energy from both the sides of paper sheet, whereas the TLC
10 plate sample settled on top of TLC itself. This is then needed to be dissolved and
purified using usual post treatment methodologies such as centrifugation,
syringe filtration and membrane filtration.
Whereas the precursor material placed over the A4 sheet got burned and the dust
particles also got dissolved into the solution. After purification, the obtained
15 Carbon Quantum Dots (CQDs) exhibited consistent characteristics,
demonstrating that the type of plate used for deposition does not significantly
impact their properties, if it is an easily flammable or flammable substance-coated
plate.
The Quantum Yield (Q.Y.) of the purified CQDs was calculated using a relative
20 method, with Quinine sulfate as the reference solvent. The measured Q.Y. values
are as follows:
• Acetone-derived CQDs: 67.4%,
• Ethanol-derived CQDs: 63.7%, and
• Methanol-derived CQDs: 52%.
25 Accordingly, all the samples demonstrated a Q.Y. exceeding 50%.
The sample mounting Quartz cuvette also contributes to the reflections that take
part inside the chamber.
11
The chamber set up is as shown in Figure 1. The schematic setup utilizes a solar
power convergent lens to focus solar energy onto the entrance of a
Buckminsterfullerene hexagonal chamber. Within this chamber, light is
manipulated by a sophisticated optical arrangement. This includes four convex
lenses, each with a focal length of 5mm, strategically 5 arranged at the four edges
of the fullerene structure. The remaining internal surfaces of the hexagonal and
pentagonal sides of the fullerene chamber are lined with 50mm x 50mm mirrors.
The entire chamber is enclosed by a double convex lens, serving as the exit or
final optical element. This collision inside the chamber leads to multiple total
10 internal reflections. The 12 pentagonal faces are fixed with mirrors and 20
hexagonal faces with lenses as shown in Figure 2, over the aluminum foil covered
cardboard sheets. This is then assigned in a way that the sample and cuvette (3ml)
can be kept inside through a middle hexagonal cavity that is removable and can
be replaced. The sample placing A4 sheet paper/ TLC is of size (30mm x 30mm),
15 which can be adjusted and increased proportionally to that of the chamber that
we are using. The industrial level scaling up of set up is hence can be done costefficiently,
with natural precursor material and using solar power consumption.
The proposed method to potentially improve industrial working hours involves
the use of a commercially available 3mW green laser light pointer. The process
20 entails a continuous laser beam from the 3mW green laser pointer is applied for
a duration ranging from 200 to 250 seconds. This irradiation sequence is repeated
three times in a row. A time duration of 120 seconds (2 minutes) is observed
between each successive laser beam irradiation.
This result also shows a better yield, as this can be practiced at night timings or
25 whenever the sunlight availability is poor. This method hence provides a backup
plan for the industries with poor sunlight availability and during night hours.
The inner set ups are same as sunlight concentration, but there is no need of
12
convex lens set up for concentrated beam, the set-up is depicted along with
sunlight mediated preparation as shown in Figure 1.
The aforementioned procedure is a method for synthesis, which is used to deposit
C-dot in the targeted spots for different applications, such as corrosion inhibition.
The chamber which is used to keep the 5 TLC plate is metallic, double wall
insulated with mirrors that can undergo total internal reflection inside the
chamber. The construction of the chamber is in such a way that it can keep the
energy focused inside the chamber, which can act as an energy resource for CD
production, which resembles the principle of CSP (Concentrating solar
10 collectors).
Plant-based extracts (ethanolic/methanolic/acetone) have been tried so far for
the synthesis procedure. The targeted synthesis and coatings can be done on
metallic pieces for corrosion inhibition applications using this method. The
15 minimal impurity content can be ensured by using filtered extract precursors.
Results:
UV-Visible Analysis Result for solvents, Ethanol(E), Acetone (A), and
Methanol(M) are shown in figure 3. The dominant peaks are seen at 217nm and
284nm for Ethanol solvents, 209nm and 282nm for Aceton solvents as well as
20 194nm and 279nm for Methanol solvents are characteristics for CQD,
corresponding to n-p* and p- p* transitions of sp2 hybridized carbon core
structures present in the sample. The inset figure shows fluorescent nature of
prepared sample under UV-light.
PL Analysis Results for the same set of samples synthesized are as shown in
25 figure 4(a): For PL of Ethanol solvent-based sample, 4(b): For PL of Acetone based
sample and 4(c): For PL of Methanol solvent-based sample. The excitationdependent
emission with blue shift is shown by the samples, which indicates the
13
formation of CQDs. The Ethanol sample for 370nm to 410nm excitation
wavelength shows 422nm to 416nm shift, the shift points for acetone sample
shows 422 corresponds to 370nm excitation and 416 corresponds to 410nm
excitation. The methanol sample results for the same are 418 for 360nm and 414
for 410nm excitation. These results are t 5 he best indication of CQDs formation.
The excitation wavelengths given lies in the range of 360-410nm, which
corresponds to the formation of CQDs, with the resultant excitation- dependent
emission with blue- shift. These confirmations along with the UV-Visible
absorption peaks and the colour change of the solution under UV- light shows
10 clearly the formation of CQDs.
Accordingly, the invention provides the following advantages:
• Solar Energy Utilization: The core of the method involves using a convex
lens to converge sunlight to a single focal point, providing concentrated
solar energy for CQD formation.
15 • Enclosed Reaction Chamber: A specially designed chamber, featuring
metallic, double-wall insulation and internal mirrors for total internal
reflection, traps and utilizes the concentrated energy. This design mimics
the principle of Concentrating Solar Power (CSP) systems.
• Cost Effective and Greener Precursor Materials: Plant-based extracts,
20 dissolved in highly volatile solvents such as methanol, acetone, and
ethanol serve as precursor materials.
• Versatile Deposition: The method allows for targeted synthesis and
coating of CQDs on various substrates, including TLC plates and A4 sheet
paper, and importantly, on metallic pieces for corrosion inhibition.
25 • Alternative Energy Source: In the absence of sufficient sunlight, a lowenergy,
monochromatic-coherent LASER source (e.g., a 3mW green laser
14
pointer) can be used to continue the synthesis process, ensuring
continuous production.
• High Quantum Yield: The synthesized CQDs exhibit high Quantum Yield
(Q.Y.).
• Scalability: The method is described as 5 industrially scalable and costefficient
due to the use of natural precursor materials and solar power.
,CLAIMS:WE CLAIM:
1. A method for synthesizing carbon quantum dot (CQD), wherein said
method comprising the steps of:
a. providing a reaction 5 chamber having metallic, double-wall
insulation and internal mirrors arranged for total internal reflection;
b. introducing a solution comprising plant-based extracts dissolved in
a volatile solvent into the reaction chamber;
c. concentrating energy source onto the solution within the reaction
10 chamber with or without by means of a convex lens,
d. heating the solution and initiating the formation of CQDs;
e. maintaining the solution under concentrated energy source for a
period sufficient to form CQDs; and
f. recovering the synthesized CQDs,
15 enabling green, scalable, and targeted CQDs production.
2. The method as claimed in claim 1, wherein said energy source is solar
energy or laser beam using a 3mW green laser light pointer as the laser
source, applied for a duration for 200 to 250 seconds.
20
3. The method as claimed in claim 1 wherein said reaction chamber comprises
of Buckminster fullerene hexagonal chamber, includes four convex lenses,
each with a focal length of 5mm, strategically arranged at the four edges of
the fullerene structure, the remaining internal surfaces of the hexagonal and
25 pentagonal sides of the fullerene chamber are lined with 50mm x 50mm
mirrors, the entire chamber is enclosed by a double convex lens, serving as
the exit or final optical element.
16
4. The method as claimed in claim 1 wherein said organic solvent as utilized
are selected from Ethanol(E), Acetone (A), or Methanol(M) with 95% purity.
5. The method as claimed in claim 1 wherein said method provides a cost
effective, scalable and provides a high quantum 5 yield of the CQDs.