g‐C ₃ N ₄ /BiYO ₃ Composite for Photocatalytic Hydrogen Evolution

Abstract

Abstract g‐C 3 N 4 /BiYO 3 composites were prepared by an electrostatic self‐assembly of g‐C 3 N 4 and BiYO 3 and were used as photocatalysts for photocatalytic hydrogen evolution. The UV‐vis DRS revealed that the band gaps of BiYO 3 and g‐C 3 N 4 were 2.58 eV and 2.96 eV, respectively, and the g‐C 3 N 4 /BiYO 3 composites showed stronger visible light absorption than that of g‐C 3 N 4 because the composite with BiYO 3 served as a narrow bandgap catalyst. Electrochemical impedance spectroscopy (EIS) proved that the g‐C 3 N 4 /BiYO 3 composites exhibited a better electronic transmission capacity and a larger photocurrent than that of g‐C 3 N 4 or BiYO 3 because the BiYO 3 acted as an electron acceptor in the composites. The PL spectra showed that g‐C 3 N 4 combined with BiYO 3 inhibited the recombination of photo‐generated electron holes in g‐C 3 N 4 and enhanced the photocatalytic activity for hydrogen evolution. Furthermore, the photocatalytic activities for hydrogen evolution with the g‐C 3 N 4 /BiYO 3 composites were higher than those of the individual g‐C 3 N 4 or BiYO 3 alone due to the transfer of photogenerated electrons from the conduction band of g‐C 3 N 4 to the conduction band of BiYO 3 and the transfer of photogenerated holes from the valence band of BiYO 3 to the valence band of g‐C 3 N 4 . The composite with a g‐C 3 N 4 /BiYO 3 mass ratio of 2 showed an optimal hydrogen evolution rate of 37.6 μmol⋅h –1 ⋅g cat –1 , which was 8.4‐ and 6.4‐fold higher than that of g‐C 3 N 4 and BiYO 3 , respectively.