Dehydrated UiO‐66(SH)2: The Zr−O Cluster and Its Photocatalytic Role Mimicking the Biological Nitrogen Fixation. (9th February 2022)

• Record Type: Journal Article
• Authors: Guo, Binbin; Cheng, Xiyue; Tang, Yu; Guo, Wei; Deng, Shuiquan; Wu, Ling; Fu, Xianzhi
• Is Part Of: Angewandte Chemie. Volume 134:Number 13(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-09
• Subjects: First-Principles Calculations -- MOFs -- Nitrogen Fixation -- Photocatalysis -- UiO-66(SH)2; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202117244
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: This work reports the dehydrated Zr‐based MOF UiO‐66(SH)2 as a visible‐light‐driven photocatalyst to mimic the biological N2 fixation process. The 15 N2 and other control experiments demonstrated that the new photocatalyst is highly efficient in converting N2 to ammonia. In‐situ TGA, XPS, and EXAFS as well as first‐principles simulations were used to demonstrate the role of the thermal treatment and the changes of the local structures around Zr due to the dehydration. It was shown that the dehydration opened a gate for the entry of N2 molecules into the [Zr6 O6 ] cluster where the strong N≡N bond was broken stepwise by μ‐N−Zr type interactions driven by the photoelectrons aided by the protonation. This mechanism was discussed in comparison with the Lowe–Thorneley mechanism proposed for the MoFe nitrogenase, and with emphasis on the [Zr6 O6 ] cluster effect and the leading role of photoelectrons over the protonation. The results shed new light on understanding the catalytic mechanism of biological N2 fixation and open a new way to fix N2 under mild conditions. Abstract : A dehydrated Zr‐based MOF, UiO‐66(SH)2, was found to show efficient conversion of N2 into NH3 under visible light. The revealed synergetic action of the photoelectron supported by the proton was analogous to that in molybdenum nitrogenase, however, with characteristic μ‐N−Zr type interactions inside the [Zr6 O6 ] cluster, which sheds new light on understanding the mechanism of nitrogenase.