Abstract
? 2022 Elsevier B.V.With the emergence of issues such as global warming and glaciers melting, reducing carbon emissions cannot be ignored. Ammonia can participate in the N element cycle in nature and has a huge market demand. In modern industry, the preparation of ammonia mainly relies on the Haber-Bosch process with huge energy consumption. Using clean photocatalytic method to prepare ammonia can alleviate the above problems. Here, the core-shell structure of MIL-125 @TiO2 was prepared by post solvothermal method for photocatalytic nitrogen fixation. Linker defects can appear as active sites in the residual MIL-125, which forms an obvious mesoporous structure that accelerates the exchange of electron/mass and promotes the activation of N2. The shell structure constructed by thin TiO2 nanosheets possesses a large specific surface area. And the oxygen vacancies active sites could be highly exposed for nitrogen adsorption and activation, so as to promote the occurrence of the photocatalytic reaction. The O?Ti?N covalent bond is established between the titanium-oxygen clusters in the peripheral of TiO2 and the linker in MIL-125, which improves the effective separation of electron-hole pairs. The ammonia formation rate of MIL-125 @TiO2-2 h is 102.7 μmol g?1 h?1 under simulated sunlight, which is 8 times higher than that of MIL-125. This work provides a novel idea for the preparation of photocatalytic nitrogen fixation materials with controllable structure and multiple active sites.
NSTL
Elsevier