Construction of Co3O4 nanopolyhedra with rich oxygen vacancies from ZIF-67 for efficient photocatalytic nitrogen fixation.

ABSTRACT

Photocatalytic nitrogen fixation has attracted much attention due to the fact that it is a way of using solar energy to achieve clean and sustainable conversion of nitrogen to ammonia under mild conditions. In this paper, different proportions of Zn-doped Co3O4 nanopolyhedrons were synthesized using bimetallic ZIFs containing Co2+ and Zn2+ as precursors for the construction of photocatalytic nitrogen fixation semiconductor materials for the first time. The synthesized Co3O4 nano-polyhedron still retains the rhombic dodecahedron shape of ZIF-67 and exhibits a large specific surface area. Moreover, Zn doping results in abundant oxygen vacancies on the surface of Co3O4 polyhedron. These oxygen vacancies not only provide active sites for nitrogen adsorption and activation, but also enhance the separation ability of photocarriers, which can significantly improve the efficiency of photocatalytic nitrogen fixation of the material. When Zn-Co3O4-30 is utilized as the catalyst for photocatalytic nitrogen fixation, the nitrogen fixation rate is 96.8 µmol g-1 h-1, which is much higher than that of pure-Co3O4. In this study, heteroatom-doped Co3O4 polyhedron with rich oxygen vacancy was synthesized by low-temperature oxidation method, which provides a new idea for the design and synthesis of skeleton-based photocatalytic nitrogen fixation materials.