Photocatalytic degradation of formaldehyde by nitrogen-doped graphene quantum dots under various light conditions

This study investigates the photocatalytic degradation of formaldehyde by nitrogen-doped graphene quantum dots (N-doped GQDs) under simulated indoor lighting. Adhering to ASHRAE Standard 145.1 for indoor air quality, the research utilized a breakthrough capacity test system (BTCTS) to evaluate formaldehyde removal efficiency. N-doped GQDs, a novel nanomaterial, demonstrated exceptional formaldehyde decomposition efficacy under LED visible light. These N-GQDs were synthesized via a microwave-assisted method and characterized by XRD, HR-TEM, XPS, and UV–Vis spectroscopy.

Five formaldehyde concentrations, 8 to 30 times the Taiwanese EPA's 0.08 ppm standard, were used to assess N-doped GQDs' performance across varying exposure levels. The impact of light spectrum on degradation was analyzed using four common indoor light sources. Results consistently showed N-doped GQDs effectively reducing formaldehyde concentrations under all tested conditions. Blue light (400–500 nm) yielded the highest degradation efficiency due to its matching excitation wavelength with N-GQDs. The photocatalytic process followed a pseudo-second-order kinetic model, suggesting a favorable reaction pathway. These findings highlight N-doped GQDs' potential as promising photocatalysts for indoor air purification. Integrating N-doped GQDs into building materials can significantly improve indoor air quality, thereby protecting occupant health and well-being.