Li Feng-Rui, Ji Tuo, Chen Wei-Chao, Du Wei, Hao Yi-Jia, Sun Yan-Li, Chen Wei-Lin
Department of Applied Chemistry, College of Arts and Sciences, Northeast Agricultural University, Harbin 150030, China.
Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024, China.
Inorg Chem. 2024 Jan 8;63(1):593-601. doi: 10.1021/acs.inorgchem.3c03472. Epub 2023 Dec 16.
In nature, biological nitrogen fixation is accomplished through the π-back-bonding mechanism of nitrogenase, which poses significant challenges for mimic artificial systems, thanks to the activation barrier associated with the N≡N bond. Consequently, this motivates us to develop efficient and reusable photocatalysts for artificial nitrogen fixation under mild conditions. We employ a charge-assisted self-assembly process toward encapsulating one polyoxometalate (POM) within a dehydrated Zr-based metal-organic framework (d-UiO-66) exhibiting nitrogen photofixation activities, thereby constructing an enzyme-mimicking photocatalyst. The dehydration of d-UiO-66 is favorable for facilitating nitrogen chemisorption and activation via the unpaired d-orbital electron at the [ZrO] cluster. The incorporation of POM guests enhanced the charge separation in the composites, thereby facilitating the transfer of photoexcited electrons into the π* antibonding orbital of chemisorbed N for efficient nitrogen fixation. Simultaneously, the catalytic efficiency of SiWFe@d-UiO-66 is enhanced by 9.0 times compared to that of d-UiO-66. Moreover, SiWFe@d-UiO-66 exhibits an apparent quantum efficiency (AQE) of 0.254% at 550 nm. The tactics of "working-in-tandem" achieved by POMs and d-UiO-66 are extremely vital for enhancing artificial ammonia synthesis. This study presents a paradigm for the development of an efficient artificial catalyst for nitrogen photofixation, aiming to mimic the process of biological nitrogen fixation.
在自然界中，生物固氮是通过固氮酶的π-反馈键合机制完成的，由于与N≡N键相关的活化能垒，这对模拟人工系统提出了重大挑战。因此，这促使我们开发在温和条件下用于人工固氮的高效且可重复使用的光催化剂。我们采用电荷辅助自组装过程，将一种多金属氧酸盐（POM）封装在具有氮光固定活性的脱水锆基金属有机框架（d-UiO-66）中，从而构建一种模拟酶的光催化剂。d-UiO-66的脱水有利于通过[ZrO]簇处未配对的d轨道电子促进氮的化学吸附和活化。POM客体的掺入增强了复合材料中的电荷分离，从而促进光激发电子转移到化学吸附氮的π*反键轨道中以实现高效固氮。同时，SiWFe@d-UiO-66的催化效率比d-UiO-66提高了9.0倍。此外，SiWFe@d-UiO-66在550 nm处表现出0.254%的表观量子效率（AQE）。POM和d-UiO-66实现的“串联工作”策略对于增强人工合成氨极为重要。本研究提出了一种开发用于氮光固定的高效人工催化剂的范例，旨在模拟生物固氮过程。
