K and halogen binary-doped graphitic carbon nitride (g-C3N4) toward enhanced visible light hydrogen evolution

Abstract Water splitting driven by solar energy to produce hydrogen, which is highly dependent on the designing of semiconductor photocatalyst, is an efficient technology to address energy shortage problems and environment issues simultaneously. Here, the halogen and potassium binary-doped graphitic carbon nitride (named as X-K-C3N4, X = F, Cl, Br, I) photocatalysts were synthetized via simply one pot thermal polymerization method, which shown optimized band structure, enhanced optical absorption, higher separation rate of photogenerated carriers, and thus improved photocatalytic performance under visible light irradiation. As result, F–K–C3N4 is demonstrated to be highly efficient in the separation and transfer of carriers owing to the existence of C–F bond, C N triple bond and K junction. The F–K–C3N4 shows a highest H2 evolution rate of 1039 μmol g−1 h−1 and a remarkable stability under visible light irradiation (λ ≥ 420 nm), which is about 8.5 times higher than that of pristine g-C3N4.