Journal
ACS NANO
Volume 15, Issue 7, Pages 12006-12018Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.1c03293
Keywords
CO2RR; syngas; undercoordinated; single atom; defects; holey graphene; electrolyzer
Categories
Funding
- Australian Research Council (ARC) Research Hub on Integrated Energy Storage Solutions [IH180100020]
- ARC Training Centre for Global Hydrogen Economy [IC200100023]
- UNSW Digital Grid Futures Institute, UNSW Sydney
- Ministry of Science and Technology of Taiwan [MOST 107-2113-M002-008-MY3, MOST 110-2113-M-003-008-MY3]
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In this study, a top-down approach was proposed for the controlled preparation of undercoordinated Ni-N-x and Fe-N-x catalysts within a holey graphene framework, for the electrochemical CO2 reduction reaction to synthesis gas. The findings demonstrated that these catalysts can be combined in any proportion to produce a desired syngas ratio, necessary for the Fischer-Tropsch synthesis of liquid fuels and chemicals. The results also showed the potential of these catalysts for scale up, with high mass-normalized activity and stability in a high-throughput gas diffusion electrolyzer.
In this study, we propose a top-down approach for the controlled preparation of undercoordinated Ni-N-x (Ni-hG) and Fe-N-x (Fe-hG) catalysts within a holey graphene framework, for the electrochemical CO2 reduction reaction (CO2RR) to synthesis gas (syngas). Through the heat treatment of commercial-grade nitrogendoped graphene, we prepared a defective holey graphene, which was then used as a platform to incorporate undercoordinated single atoms via carbon defect restoration, confirmed by a range of characterization techniques. We reveal that these Ni-hG and Fe-hG catalysts can be combined in any proportion to produce a desired syngas ratio (1-10) across a wide potential range (-0.6 to -1.1 V vs RHE), required commercially for the Fischer-Tropsch (F-T) synthesis of liquid fuels and chemicals. These findings are in agreement with our density functional theory calculations, which reveal that CO selectivity increases with a reduction in N coordination with Ni, while unsaturated Fe-N-x sites favor the hydrogen evolution reaction (HER). The potential of these catalysts for scale up is further demonstrated by the unchanged selectivity at elevated temperature and stability in a high-throughput gas diffusion electrolyzer, displaying a high-mass-normalized activity of 275 mA mg(-1) at a cell voltage of 2.5 V. Our results provide valuable insights into the implementation of a simple top-down approach for fabricating active undercoordinated single atom catalysts for decarbonized syngas generation.
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