Visible/near-infrared driven highly efficient photocatalyst based on upconversion nanoparticles/g-C3N4 nanocomposite

Graphitic carbon nitride (g-C₃N₄) is widely considered as a promising visible-driven photocatalyst. It is a type of inexpensive, air-stable, and non-toxic material that has been proven to exhibit high performance in photocatalysis. For more efficient use of solar energy, it is necessary to enhance the light absorption of g-C₃N₄. To take advantage of the near-infrared (NIR) region of the solar energy, g-C₃N₄ was combined with upconversion nanoparticles (UCNPs), in this study. The UCNPs can convert NIR photons into ultraviolet (UV) and visible light, which can then activate the g-C₃N₄ photocatalyst. The use of visible and NIR light sources improves the photocatalytic activity of the UCNPs/g-C₃N₄ nanocomposite. In order to optimize the photocatalytic efficiency of the nanocomposite, the absorption and emission wavelengths of the UCNPs were tuned by controlling the lanthanide dopant composition where the core UCNPs were coated with an inner active shell and an outer inert shell. It is shown in this study that the nanocomposite can exhibit excellent photocatalytic activities under simulated solar light illumination.