Amorphous MOF / Crystalline Bi₂MoO₆ Heterojunction Interfaces: Engineering Quantum Dots and Electron Bridges for...

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 (V_M) 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.