Recent Advances in MOF‐Based Materials for Photocatalytic Nitrogen Fixation

Abstract

Solar‐driven photocatalytic nitrogen fixation is a low‐energy and environmentally friendly strategy for NH3 synthesis, which is considered as a possible alternative to the Haber‐Bosch (HB) process. Considering the extremely high bond energy of N2, the choice of photocatalysts is essential for nitrogen reduction reaction (NRR). As a class of porous materials with high crystallinity and adjustable organic ligands, metal‐organic frameworks (MOFs) have been proven to exhibit high photocatalytic activity for a lot of reactions. Recently, MOFs and MOF‐based functional materials have become a kind of promising photocatalysts for NRR. In this minireview, we provide a comprehensive overview of the work reported so far on the MOF and MOF‐derived photocatalysts for the nitrogen fixation. Through the comprehensive analysis of the structures, nitrogen fixation performances and mechanisms of these photocatalysts, this minireview provides a reference for the design of new photocatalysts based on MOF materials.

Research Progress and Perspectives on Active Sites of Photo- and Electrocatalytic Nitrogen Reduction

“…Therefore, ion chromatography is a more accurate and convenient method for ammonia detection and quantitative measurement. Nevertheless, the reliability of IC is still not sufficient when the concentration of NH 4 + is <100 μg·L –1 under alkaline condition, although the pH limit of IC is extended to 12. ,, …”

“…Accordingly, it is crucial to explore green, economical, and energy-saving techniques for ammonia synthesis under ambient conditions . Photocatalysis (PC) and electrocatalysis (EC) are emerging as promising strategies and have been rapidly developed over the past few years due to their low-cost and abundant raw materials (air and water) as well as mild reaction conditions. − …”

Advances in Semiconductor-Based Nanocomposite Photo(electro)catalysts for Nitrogen Reduction to Ammonia

“…At present, heterojunction electrocatalysts are mainly concentrated on type-II catalysts. Hu et al [ 57 ] have proven that compared with g–C 3 N 4 or ternary metal sulfide, the construction of g–C 3 N 4 with ternary metal sulfide could significantly improve the nitrogen fixation efficiency. When the mass fraction of ZnMoCdS was 80%, the heterojunction system had the highest nitrogen fixation capacity.…”

Recent progress of photocatalysts based on tungsten and related metals for nitrogen reduction to ammonia

“…MOFs are micro-mesoporous hybrid materials composed of metal ion nodes connected with organic linkers together or clusters and organic frameworks. Similar excitation characteristics of electron-hole pairs endow MOFs and their derivatives with intriguing semiconductor-like properties in various photochemical reactions ( Hu et al, 2022 ). High microporosity and diverse functionalities enable the introduction of defined and highly exposed metal nodes onto the larger surfaces to promote or catalyze targeted reactions ( Hao et al, 2021 ; Lin Wang et al, 2022 ).…”

“…The dehydration opened a “gate” for the entry of N 2 molecules into the [Zr 6 O 6 ] cluster, of which three active cage modes strongly bound with N 2 molecules and drive the cleavage of N≡N bond by the photoelectrons ( Figure 13E ). However, most MOF-related photocatalysts focused either on the coordination environment around the metal nodes, or the role of photosensitive ligands or single transition metals ( Hu et al, 2022 ). Gao and co-authors presented photo-excited cluster defects and linker defects to revamp the photocatalytic NRR performance of UiO-66 ( Gao et al, 2021 ).…”