Water is arguably the most crucial resource on Earth. The efficient removal of organic compounds, such as dyes and pharmaceuticals, is essential to preserve our water resources, something at which conventional wastewater treatments are inefficient. As an alternative, photocatalytic technologies may achieve a near-complete degradation of pollutants by harnessing the energy of a light source. Titanium dioxide (TiO2) is a stable and inexpensive photocatalyst that is widely used across several areas but presents some limitations: requiring high-energy UV radiation, which is only a small fraction of solar radiation; suffering from rapid charge recombination; lowering its photonic efficiency; and poor affinity towards organic compounds.
Combining TiO2 with carbon dots (CDs) may bridge these limitations. CDs are carbon-based nanoparticles with interesting properties, such as high photoluminescence, broadband absorption, and good water solubility. Their unique properties and the easiness of their preparation enable the use of CDs for several applications, including sensing, LEDs, and photocatalysis.
Herein, we report the integration of CDs with TiO2 to prepare an efficient photocatalytic nanocomposite for the solar-light-driven photodegradation of organic pollutants. In the first stage, by adding CDs, we developed a composite with an enhanced potential for the photodegradation of methylene blue (MB), increasing efficiency by 367% when compared to bare TiO2. Building on this, we modified the composite to include corn stover, a major waste material of the corn industry, as part of the CDs. This way, we created high-value products from an otherwise unused waste source, promoting a circular economy, while maintaining catalytic performance. The composite was thoroughly characterized via SEM, FTIR, XPS, NMR, XRD, and UV-Vis and fluorescence spectroscopy. Finally, we tackled the removal of ciprofloxacin using this method, achieving a virtually complete degradation of 20 ppm within 20 minutes of solar-light irradiation, with the CDs significantly improving efficiency when compared to TiO2.
