Amorphous MOF / Crystalline Bi2MoO6 Heterojunction Interfaces: Engineering Quantum Dots and Electron Bridges for Synergistic High-Efficiency Photocatalytic Nitrogen Fixation.

Conventional photocatalysts pronounced electron-hole recombination and a limited number of active sites. To address these challenges, Bi-N bridged bonds were interlinked at the interface of the heterojunction via coating crystalline Bi2MoO6 with amorphous MOF (Bi2MoO6@ZIF-Fe). Simultaneously, Bi metal vacancies (VM) and MoO3 quantum dots (QDs) were formed to accelerate the transfer of electrons (e-). This system facilitates the formation of an S-scheme heterojunction, in which photogenerated holes (h+) are attracted by metal vacancies, thereby suppressing the recombination of photogenerated charge carriers. Meanwhile, electrons (e-) in the amorphous ZIF-Fe valence band (VB) and the Bi2MoO6 conduction band (CB) were involved in the photocatalytic reaction. The highest visible light catalytic activity for nitrogen fixation in pure water was measured at 4551.38 µmol L-1 g-1 h-1. A nitrogen fixation performance of 6309.1 µmol L-1 g-1 h-1 was attained using methanol as a sacrificial agent (water/methanol = 95/5, v/v). Density functional theory (DFT) calculations, including ab initio molecular dynamics (AIMD) simulations of amorphous ZIF-Fe, reveal that the presence of Bi-N bridges facilitates the formation of rapid electron transfer pathways. Concurrently, the inclusion of MoO3 quantum dots significantly enhances the capabilities of electron transfer and accelerates the process in amorphous ZIF-Fe-based heterojunctions.