Kg-Scale Synthesis of Ultrathin Single‐Crystalline MOF/GO/MOF Sandwich Nanosheets with Elevated Electrochemical Performance

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Summary:
The authors from China University of Petroleum (East China) developed ultrathin single-crystalline MOF/GO/MOF (MGM) sandwich nanosheets with 4 nm thickness, achieving 98.73 % kg-scale yield and record electrochemical performance in sodium-ion batteries (593 mA h g⁻¹), aqueous Zn batteries (159 mA h g⁻¹) and OER catalysis (224 mV @ 10 mA cm⁻²).

Background:
1. To address the low yield and poor stability of 2D MOF nanosheets, previous researchers exfoliated bulk MOFs or used surfactant-assisted growth, yet scalability and active-site exposure remain bottlenecks.
2. The authors propose a GO-directed bottom-up synthesis that lowers surface free energy (−8.06 eV Å⁻²) and prevents Ostwald ripening, producing kg-scale MGM nanosheets with fully exposed Ni/Co active centers.

Research Content:
1. Synthesis: One-pot reflux of Ni(NO₃)₂·6H₂O, Co(NO₃)₂·6H₂O, BDC and GO in DMF/EG/H₂O at 140 °C for 72 h; solvent recycling validated.
2. Characterizations:
   1) BET 14.23 m² g⁻¹; mesopore ~3.8 nm.
   2) SEM/TEM reveal 4.3 µm lateral size, 4 nm thickness; cryo-HRTEM shows 9.9 Å (200) lattice fringes.
   3) Four-probe conductivity 1.03×10⁻⁶ S cm⁻¹; XPS confirms Ni²⁺/Co²⁺; TG shows 7 wt % GO.
3. Application:
   – SIB anode: 406.5 mA h g⁻¹ after 260 cycles @ 0.5 A g⁻¹, 79 % capacitive contribution.
   – Zn-battery cathode: 159.2 mA h g⁻¹ @ 1 A g⁻¹, 57 % capacity retention @ 10 A g⁻¹, 101 Wh kg⁻¹ energy density.
   – OER catalyst: η₁₀ = 224 mV, Tafel 123 mV dec⁻¹, stable after 5000 CV cycles.
4. Mechanism: GO π–π stacks with BDC, directing 2D growth; EG + GO lower surface energy, suppressing ripening; ultrathin structure shortens ion/electron paths and exposes unsaturated Ni/Co-O octahedra for Na⁺ insertion, OH⁻ adsorption and redox catalysis.

Outlook:
The work delivers a scalable, low-cost route to kg-scale 2D MOF nanosheets with tri-functional energy-storage/catalysis superiority, paving the way for industrial MOF-based devices.

Kg-Scale Synthesis of Ultrathin Single‐Crystalline MOF/GO/MOF Sandwich Nanosheets with Elevated Electrochemical Performance
Authors: Ziyi Li, Yongxin Wang, Xiaofei Wei, Mengjia Han, Binggang Li, Fei Zhao, Weidong Fan, Wenmiao Chen, Wenpei Kang, Lili Fan, Ben Xu*, Daofeng Sun*
DOI: 10.1002/adma.202505700
Link: https://onlinelibrary.wiley.com/doi/10.1002/adma.202505700

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