Enhanced artificial nitrogen fixation efficiency induced by construction of ternary TiO2/MIL-88A(Fe)/g-C3N4 Z-scheme heterojunction

Abstract

Herein, a ternary TiO₂/MIL-88A(Fe)/g-C₃N₄ heterojunction is successfully constructed through a facile hydrothermal strategy for enhancing solar energy harvesting and efficiency of catalytic nitrogen reduction induced by enlarged light absorption range, increasing interfacial charge transfer ability and desirable stability. Under the simulated sunlight irradiation, the N₂ fixation experiment shows that the yield of NH₃ reaches 1084.31 μmol/(g·h) over the TiO₂/MIL-88A(Fe)/g-C₃N₄ photocatalyst, and the yield is significantly enhanced, which is 33.68 and 13.94 times that is higher than the pure TiO₂ and g-C₃N₄, respectively. In a mean time, the excellent performance of the photocatalytic N₂ fixation over the ternary TiO₂/MIL-88A(Fe)/g-C₃N₄ is verified based on density function theory calculation and the decisive step over the composite is investigated by calculating Gibbs free energies of nitrogen reduction paths. The performance enhancement mechanism of TiO₂/MIL-88A(Fe)/g-C₃N₄ is speculated, which indicates that the hybridized three-component system presents a desirable Z-scheme band alignment, resulting in the improvement of separation and transfer efficiency of photoinduced charge carriers. The article shows a new and high-efficiency TiO₂/MIL-88A(Fe)/g-C₃N₄ photocatalysis for excellent nitrogen reduction ability.