Nitrogen-Doped Carbon Quantum Dots from Fruit Waste
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Solution Overview
Problem
Existing methods for synthesizing carbon quantum dots lack a cost-effective and efficient approach to enhance their luminescent properties, particularly due to the absence of a suitable bandgap, which limits their application as efficient fluorescent materials.
Innovation Solution
A method involving the hydrothermal reaction of a mixture containing fruit waste material, a nitrogen source, and deionized water in an autoclave at temperatures ranging from 150°C to 250°C to produce nitrogen-doped carbon quantum dots with improved luminescent properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon quantum dots are synthesized using conventional methods, then they can be produced, but their luminescent properties are insufficient due to absence of suitable bandgap
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition through nitrogen doping. The carbon quantum dots are synthesized with nitrogen-containing compounds as precursors or dopants, which fundamentally changes the electronic structure and creates suitable bandgap for luminescence. This parameter modification (adding nitrogen) directly addresses the luminescent performance issue without requiring complex multi-step processes.
Solution Approach 2:
The patent creates composite nitrogen-doped carbon quantum dots by combining carbon-based materials with nitrogen elements. This composite approach integrates the beneficial properties of both components: the carbon matrix provides structural stability while nitrogen doping introduces appropriate bandgap and enhances luminescent properties, resolving the contradiction between performance and synthesis simplicity.
2Reliability
If nitrogen doping is applied to enhance photoluminescence properties, then Stokes shift and quantum yield are improved, but synthesis process becomes more complex
Solution Approach 1:
The patent merges the carbonization process with nitrogen doping into a single integrated hydrothermal synthesis step. Instead of separately synthesizing carbon quantum dots and then performing additional doping procedures, the method combines both functions by using nitrogen-containing precursors during the initial hydrothermal treatment. This merging eliminates multiple processing steps while achieving the desired nitrogen-doped structure with enhanced photoluminescence properties.
Solution Approach 2:
The synthesis method employs self-service by allowing the nitrogen-containing precursor to automatically incorporate nitrogen into the carbon quantum dot structure during the hydrothermal carbonization process. The system self-regulates the doping level based on the precursor concentration and reaction conditions, eliminating the need for complex external doping equipment or multiple processing stages.
3Ease of manufacture
If biomass materials are used as precursors, then cost-effectiveness and environmental friendliness are improved, but control over doping level becomes more difficult
Solution Approach 1:
The patent applies parameter changes by systematically adjusting the concentration ratio of nitrogen-containing precursor to biomass material in the hydrothermal synthesis. By varying this parameter, the nitrogen doping level can be precisely controlled while maintaining the use of cost-effective biomass precursors. The method establishes clear parameter ranges that ensure reproducible doping levels without requiring expensive or complex materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The synthesized nitrogen-doped carbon quantum dots exhibit enhanced Stokes shift and photoluminescence quantum yield, making them suitable for applications in solar cells and light-emitting diodes, while also being environmentally friendly and cost-effective.
Implementation Method 1
reacting a mixture of a fruit waste material, a nitrogen source, and deionized water hydrothermally in an autoclave at a reaction temperature in a range of 150° C. to 250° C. to form a nitrogen-doped carbon quantum dot containing suspension
Implementation Method 2
Photoluminescence (PL) quantum yield (PLQY) and Stokes shift (SS) are important luminescence properties that play a role in improving the performance of solar cells and light-emitting diodes (LED). PLQY and SS can be enhanced via doping of pristine CQDs by heteroatoms such as B, N, S, P, etc.
Implementation Method 3
The method includes centrifuging the carbon quantum dot containing suspension to separate the nitrogen-doped carbon quantum dots from a hydrochar
Implementation Method 4
The method includes filtering the nitrogen-doped carbon quantum dot containing suspension to obtain the nitrogen-doped carbon quantum dots
Data Source
AI summary
A method for synthesizing nitrogen-doped carbon quantum dots. The method includes reacting a mixture of a fruit waste material, a nitrogen source, and deionized water hydrothermally in an autoclave at a reaction temperature in a range of 150° C. to 250° C. to form a nitrogen-doped carbon quantum dot containing suspension. The method includes centrifuging the carbon quantum dot containing suspension to separate the nitrogen-doped carbon quantum dots from a hydrochar. The method includes filtering the nitrogen-doped carbon quantum dot containing suspension to obtain the nitrogen-doped carbon quantum dots. The nitrogen-doped carbon quantum dots have a size ranging from 1 to 5 nanometers (nm). The nitrogen-doped carbon quantum dots have a Stokes shift of at least 140 nm at an excitation wavelength of 300-420 nm.