Boron Precursor-Dependent Evolution of Differently Emitting Carbon Dots.

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Carbon dots (CDs) are nanomaterials with tunable photoluminescence.
• Boron doping is explored to modify CD properties, creating electron-deficient states.
• Understanding boron precursor effects on CD synthesis and photophysics is crucial.

Purpose of the Study:

• To investigate the impact of various boron precursors on carbon dot synthesis and photophysical properties.
• To develop boron-doped carbon dots (BCDs) for sensitive detection of Fe(III) and ascorbic acid (AA).
• To elucidate the relationship between boron doping, surface defects, and optical behavior through experimental and theoretical studies.

Main Methods:

• Hydrothermal treatment of ascorbic acid (AA) with different boron precursors (borax, boric acid, sodium borate, sodium borohydride).
• Characterization of synthesized boron-doped carbon dots (BCDs) including size, emission, and fluorescence intensity.
• Application of the most fluorescent BCD for Fe(III) detection via fluorescence "Turn Off" and subsequent AA detection via fluorescence recovery.
• Interference-free quantitative analysis of Fe(III) and AA in real samples.
• Theoretical calculations to explain optical properties and charge polarization.

Main Results:

• Synthesis of BCDs (<6 nm) with varying sizes, emission maxima (~15 nm shifts), and fluorescence intensities, dependent on boron precursors.
• Identification of a highly fluorescent BCD (quantum yield ~5%) from borax-mediated synthesis.
• Demonstration of nanomolar level detection of Fe(III) using the fluorescence "Turn Off" phenomenon.
• Facilitation of nanomolar level detection of AA through fluorescence recovery after Fe(III) detection.
• Experimental and theoretical evidence of boron doping-induced surface defects and charge polarization, leading to red-shifted absorption spectra.

Conclusions:

• Boron doping significantly alters the photophysical properties of carbon dots.
• The choice of boron precursor critically influences BCD characteristics and performance.
• Developed BCDs offer a sensitive and selective platform for simultaneous detection of Fe(III) and AA in aqueous samples.
• This work provides new insights into the photophysics of boron-doped carbon dots and their potential applications in sensing.