Enhanced visible-light photocatalytic activity of a g-C3N4/BiVO4 nanocomposite: a first-principles study.

The structural, electronic, and optical properties of a g-C3N4(001)/BiVO4(010) nanocomposite have been investigated using first-principles calculations. The results indicate that g-C3N4(001) can stably adsorb onto the BiVO4(010) surface, and it tends to form a regular wavy shape. The calculated band gap of the g-C3N4(001)/BiVO4(010) nanocomposite is narrower compared with that of BiVO4 or BiVO4(010), primarily due to the introduction of N 2p states near the Fermi level. The g-C3N4(001)/BiVO4(010) nanocomposite has a favorable type-II band alignment; thus, photoexcited electrons can be injected into the conduction band of g-C3N4(001) from the conduction band of BiVO4(010). The proper interface charge distribution facilitates carrier separation in the g-C3N4(001)/BiVO4(010) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. The calculated absorption coefficients indicate an obvious redshift of the absorption edge, which is in good agreement with the experimental results. Our calculation results suggest that the g-C3N4(001)/BiVO4(010) nanocomposite has significant advantages for visible-light photocatalysis.