Preparation of Co3O4/niobate composite photocatalysts by ZIF-67 derivative for photocatalytic property of water splitting

Niobate with appropriate band gap, nontoxicity and high photocatalytic stability has been widely used for water splitting by photocatalysis. Metal-organic frame (MOF) derived metal oxide has more advantages in photocatalysis for water splitting. In this paper, the amorphous K0.027Nb0.93O3 photocatalyst was prepared by hydrothermal method, and then the Co3O4/K0.027Nb0.93O3 composite photocatalysts were obtained by calcining ZIF-67 (Co-MOF)/K0.027Nb0.93O3 in muffle at air. The XRD, SEM, TEM were used to characterize the structure and morphology of Co3O4/K0.027Nb0.93O3 composite photocatalysts. The UV–vis diffuse reflection spectra were investigated to discover the light absorption properties. The EIS and mott-schottky were determined and the results showed that the electron migration rate increased at the Co3O4/K0.027Nb0.93O3 interface. The hydrogen evolution experiments showed that Co3O4/K0.027Nb0.93O3 photocatalysts had better photocatalytic activity than the pure K0.027Nb0.93O3. What's more, the best Co3O4/K0.027Nb0.93O3 sample had the 717.84 umol g−1 h−1 for hydrogen production rate which was 3.36 times than the pure K0.027Nb0.93O3 (213.52 umol g−1 h−1). Therefore, the Co3O4 on the surface of K0.027Nb0.93O3 as the co-catalyst could really enhance the photocatalytic activity.