First Principles Study on the Electronic Structure and Optical Properties of NCQDs/TiO₂(101)

Area of Science:

• Materials Science
• Computational Chemistry
• Surface Science

Background:

• Carbon quantum dots (CQDs) and nitrogen-doped carbon quantum dots (NCQDs) are emerging nanomaterials with unique optical and electronic properties.
• Titanium dioxide (TiO2) is a widely studied photocatalyst, but its efficiency can be limited by charge recombination and light absorption.
• Surface modification of TiO2 with CQDs or NCQDs offers a promising strategy to enhance its photocatalytic performance.

Purpose of the Study:

• To investigate the effects of loading CQDs and NCQDs on the TiO2(101) surface.
• To analyze the binding energy, work function, electronic structure, and optical properties of these composite systems.
• To understand the charge transfer mechanisms and their impact on photocatalytic potential.

Main Methods:

• First-principles calculations based on Density Functional Theory (DFT).
• Investigation of binding energy, work function, electronic structure, and optical properties.
• Analysis of charge transfer and distribution using Bader charge analysis.

Main Results:

• NCQDs exhibit stronger binding affinity to the TiO2(101) surface than CQDs.
• Charge transfer from CQDs to TiO2 originates from specific carbon atoms, while NCQD-TiO2 interaction shows more uniform charge distribution.
• NCQD loading enhances photogenerated electron-hole pair generation and electron transfer.
• CQD loading results in the smallest band gap.

Conclusions:

• Nitrogen doping significantly modifies the interaction between quantum dots and TiO2 surfaces.
• NCQDs are more effective than CQDs in promoting charge separation and transfer in TiO2-based photocatalysts.
• The findings provide insights into designing advanced nanomaterials for enhanced photocatalytic applications.