3D graphene/CoO and the photocatalytic properties for hydrogen evolution from water splitting under visible light irradiation

A three-dimensional cross-linked graphene (G) supported CoO nano composite (3D G/CoO) was prepared by solvothermal reaction followed by annealing at high temperature using graphene oxide and metal organic framework (ZIF-67) as precursors. The structures and morphologies of 3D G/CoO were characterized by XRD, XPS, UV-vis diffuse reflectance spectrum, SEM and TEM. The results show that CoO particles with an average particle size of ~34.5 nm are uniformly loaded on the graphene sheets. Based on the unique hot electron emission properties of 3D G, as well as the synergetic effect between the two components, 3D G/CoO nano composites exhibit excellent photocatalytic properties for hydrogen evolution from water splitting under the irradiation. Under 300 W Xenon lamp, the hydrogen production rate is 10.1 mmol·g_cat⁻¹·h⁻¹. The apparent quantum efficiency of 7.77% is obtained at 520 nm visible light. After recycling for 5 times, the hydrogen production rate is maintained at 88%. This high-performance visible light responsive 3D photocatalyst is of great significance to the development of highly efficient catalysts in the field of photocatalysis.