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Single‐Atom Electrocatalysts from Multivariate Metal–Organic Frameworks for Highly Selective Reduction of CO₂ at Low Pressures
Summary:
The authors from the University of Science and Technology of China and Argonne National Laboratory developed a series of single-atom electrocatalysts (M₁–N–C, M = Fe, Co, Ni, Cu) derived from multivariate metal–organic frameworks (MTV-MOFs), achieving highly selective CO₂ reduction to CO even under low CO₂ pressures (15–30%).
Background:
1. To address the challenge of identifying intrinsic catalytic activity in single-atom catalysts (SACs), previous researchers synthesized various M–N–C materials, but differences in support structures obscured metal-specific performance.
2. The authors proposed a general method using isostructural MTV-MOFs to create M₁–N–C catalysts with identical supports, enabling direct comparison of metal activity.
Research Content:
1. Synthesis:
The authors synthesized M₁–N–C (M = Fe, Co, Ni, Cu) via pyrolysis of porphyrinic MTV-MOFs (M-PCN-222), followed by ZrO₂ removal.
2. Characterizations:
1) BET results show similar surface areas and pore size distributions across all M₁–N–C samples.
2) SEM/TEM images reveal rod-like morphology (~200 nm) with no visible metal nanoparticles; HAADF-STEM confirms atomically dispersed metal sites.
3) XPS and XAS confirm M–N₄ coordination; Ni K-edge EXAFS shows Ni–N₄ structure with no Ni–Ni bonding.
3. Application:
Ni₁–N–C exhibited the highest CO Faradaic efficiency (96.8%) at −0.8 V vs. RHE in pure CO₂, and maintained >80% CO selectivity even at 15% CO₂ concentration.
4. Mechanism:
DFT calculations show that Ni₁–N–C has the lowest energy barrier for *COOH formation and the most positive limiting potential difference (U_L(CO₂) − U_L(H₂)), explaining its superior selectivity for CO₂ reduction over hydrogen evolution.
Outlook:
This work provides a general platform for constructing SACs with identical supports, unambiguously revealing the superior intrinsic activity of Ni₁–N–C for CO₂ reduction, even under industrially relevant low CO₂ concentrations.
Single‐Atom Electrocatalysts from Multivariate Metal–Organic Frameworks for Highly Selective Reduction of CO₂ at Low Pressures
Authors: Long Jiao, Weijie Yang, Gang Wan, Rui Zhang, Xusheng Zheng, Hua Zhou, Shu-Hong Yu, Hai-Long Jiang
DOI: 10.1002/anie.202008787
Link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202008787
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