▎ 摘　　要

The wide band gap semiconductor is considered a potential water splitting photocatalyst. However, the wide band gap means that visible light absorption is weak and more energy is required to transfer electrons to the conduction band, which will greatly limit the photocatalytic performance. We design the SiC/RGO hetero-junction and GaN/RGO heterojunction, using first-principles hybrid density functional theory to explore whether this shortcoming can be improved. The results prove that both types of heterojunction have effectively reduced the band gap, and the light absorption capacity has been significantly enhanced. However, only the GaN/RGO heterojunction meets the conditions for photocatalytic water splitting, that is, the energy levels of water oxidation and reduction are all within its band range, thus ensuring the occurrence of water splitting. What's more, there is a potential well between the layers, which helps effectively prevent the recombination of pho-togenerated charge carriers, thereby further enhancing the photocatalytic properties of the GaN/RGO hetero-junction. Besides, the oxidation reaction and reduction reaction occur at a relatively synchronous rate in the process of water splitting. This ensures that the overall reaction proceeds at a faster rate, and also improves the efficiency of photocatalysis. What has been found above provides a reliable choice for experimenters to explore new photocatalysts.