Graphene quantum dot-sensitized Zn-MOFs for efficient visible-light-driven carbon dioxide reduction

Abstract

The development of environmentally friendly and highly active photocatalysts for carbon dioxide reduction is one of the most anticipated potential pathways for future carbon dioxide emission treatment. In this work, the rational design and construction of Zn-MOF@GQD heterostructures as efficient and stable photocatalysts were demonstrated. The unique design binds the GQDs into the holes located on the surface of the Zn-Bim-His (MOF) nanoparticles. Compared with GQDs, the obtained optimal composite (Zn-Bim-His-1@GQD) displays dramatically enhanced photoactivity as a catalyst for photocatalytic carbon dioxide conversion at the formation rates of 20.9 and 3.7 μmol h⁻¹ g⁻¹ for CH₄ and CO, respectively. The selectivity of methane production by the catalytic reaction is as high as 85%. Moreover, the Zn-Bim-His-1@GQD heterostructures also exhibit high photocatalytic stability and good reusability for the carbon dioxide reduction. The enhanced photocatalytic activity of Zn-Bim-His-1@GQDs can be attributed to the synergistic effect of the intimate contact between Zn-Bim-His-1 and GQDs and the rich active sites on the defective MOF surface. Specifically, the Zn-Bim-His-1@GQDs can effectively promote the spatial separation of the photogenerated electron–hole pairs in the catalytic conversion process. This study is anticipated to provide new opportunities to utilize carbon dot materials and porous MOF crystals in photocatalytic applications.