Efficient Electron Transfer from an Electron‐Reservoir Polyoxometalate to Dual‐Metal‐Site Metal‐Organic Frameworks for Highly Efficient Electroreduction of Nitrogen

• Published in: Advanced functional materials 2023-07, Vol.33 (28), p.n/a
• Main Authors: Yang, Mengle, Wang, Xinming, Gómez‐García, Carlos J., Jin, Zhongxin, Xin, Jianjiao, Cao, Xixian, Ma, Huiyuan, Pang, Haijun, Tan, Lichao, Yang, Guixin, Kan, Yuhe
• Format: Article
• Language: English
• Subjects: Ammonia; bimetallic strategy; Bimetals; Catalysts; Chemical reduction; Density functional theory; DFT calculations; directional electron‐transfer; electrocatalytic nitrogen reduction reaction; Electron transfer; Electrons; Fourier transforms; Materials science; Metal-organic frameworks; polyoxometalate‐based metal‐organic frameworks; Polyoxometallates; Reduction (electrolytic)
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202214495

Precise design and construction of catalysts with satisfied performance for ambient electrolytic nitrogen reduction reaction (e‐NRR) is extremely challenging. By in situ integrating an electron‐rich polyoxometalates (POMs) into stable metal organic frameworks (MOFs), five POMs‐based MOFs formulated as [FexCoy(Pbpy)9(ox)6(H2O)6][P2W18O62]·3H2O (abbreviated as FexCoyMOF‐P2W18) are created and directly used as catalysts for e‐NRR. Their electrocatalytic performances are remarkably improved thanks to complementary advantages and promising possibilities of MOFs and POMs. In particular, NH3 yield rates of 47.04 µg h−1 mgcat.−1 and Faradaic efficiency of 31.56% by FeCoMOF‐P2W18 for e‐NRR are significantly enhanced by a factor of 4 and 3, respectively, compared to the [Fe0.5Co0.5(Pbpy)(ox)]2·(Pbpy)0.5. The cyclic voltammetry curves, density functional theory calculations and in situ Fourier‐transform infrared spectroscopy confirm that there is a directional electron channel from P2W18 to the MOFs unit to accelerate the transfer of electrons. And the introduction of bimetals Fe and Co in the P2W18‐based MOFs can reduce the energy of the *N2 to *N2H step, thereby increasing the production of NH3. More importantly, this POM in situ embedding strategy can be extended to create other e‐NRR catalysts with enhanced performances, which opens a new avenue for future NH3 production for breakthrough in the bottleneck of e‐NRR. Five polyoxometalate‐based metal‐organic frameworks (POMOFs) crystal materials based on {P2W18O62}6‐ with different Fe/Co ratios are precisely designed and synthesized by a simple hydrothermal method, which own the directional electron transfer from P2W18 to FexCoy‐MOFs. Especially, Fe1Co1‐P2W18 shows more excellent NH3 yield rate (47.04 µg h–1 mgcat.–1), FE (31.76 %) and long electrocatalytic stability compared other FexCoy‐P2W18.