Well-Defined Iron Sites in Crystalline Carbon Nitride

作者：Alexandre Genoux, Magnus Pauly, Conor L. Rooney, Chungseok Choi, Bo Shang, Scott McGuigan, Majed S. Fataftah, Yves Kayser, Simon Suhr, Serena DeBeer, Hailiang Wang, Paul A. Maggard, Patrick L. Holland · 发表于：Journal of the American Chemical Society · 年份：2023 · DOI：10.1021/jacs.3c05417 · 被引用次数：35 · 研究领域：Advanced Photocatalysis Techniques、Ammonia Synthesis and Nitrogen Reduction、MXene and MAX Phase Materials

Carbon nitride materials can be hosts for transition metal sites, but Mössbauer studies on iron complexes in carbon nitrides have always shown a mixture of environments and oxidation states. Here we describe the synthesis and characterization of a crystalline carbon nitride with stoichiometric iron sites that all have the same environment. The material (formula C 6 N 9 H 2 Fe 0.4 Li 1.2 Cl, abbreviated PTI/FeCl 2 ) is derived from reacting poly(triazine imide)·LiCl (PTI/LiCl) with a low-melting FeCl 2 /KCl flux, followed by anaerobic rinsing with methanol. X-ray diffraction, X-ray absorption and Mössbauer spectroscopies, and SQUID magnetometry indicate that there are tetrahedral high-spin iron(II) sites throughout the material, all having the same geometry. The material is active for electrocatalytic nitrate reduction to ammonia, with a production rate of ca . 0.1 mmol cm –2 h –1 and Faradaic efficiency of ca . 80% at −0.80 V vs RHE.