Built-in-field carbon quantum dot-nanotube heterointerfaces enable concurrent solar H₂ evolution and pollutant...

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Biomass valorization is crucial for sustainable chemistry.
• Carbon quantum dots (CQDs) offer unique optoelectronic properties.
• Developing efficient photocatalysts for simultaneous energy and environmental applications is a key challenge.

Purpose of the Study:

• To develop a scalable method for upcycling biomass into carbon quantum dots (CQDs).
• To create dual-functional photocatalysts by integrating CQDs with titanium dioxide (TiO2) nanotubes for solar-driven hydrogen evolution and organic pollutant degradation.
• To elucidate the interfacial mechanisms governing the enhanced photocatalytic performance.

Main Methods:

• Hydrothermal carbonization of various biomass sources to produce hydrochars.
• Mild alkaline peroxide oxidation for converting hydrochars into monodisperse CQDs.
• Fabrication of CQD/TiO2 nanotube heterostructures.
• Solar photocatalysis experiments for hydrogen evolution and imidacloprid degradation.
• Photoelectrochemical measurements, spectroscopic analyses, and Density Functional Theory (DFT) calculations.

Main Results:

• Monodisperse CQDs with high quantum yields and strong visible emission were successfully synthesized from diverse biomass.
• The CQD/TiO2 nanotube composites exhibited excellent dual-functionality, achieving significant hydrogen evolution and organic pollutant degradation rates.
• Optimized composite (CTN3) showed high stability over five cycles with minimal performance loss.
• CQD integration improved charge carrier separation and utilization by reducing interfacial resistance and recombination.

Conclusions:

• A scalable and sustainable route to upcycle biomass into functional CQDs for photocatalysis was established.
• The CQD/TiO2 nanotube heterostructures represent highly efficient dual-functional photocatalysts for energy-environment applications.
• Interfacial electronic coupling and charge redistribution, supported by DFT, are key to the enhanced performance, paving the way for advanced photocatalyst design.