Abstract
Electrochemical CO2 reduction is a potential approach to convert CO2 into valuable chemicals using electricity as feedstock. Abundant and affordable catalyst materials are needed to upscale this process in a sustainable manner. Nickel-nitrogen-doped carbon (Ni-N-C) is an efficient catalyst for CO2 reduction to CO, and the single-site Ni−Nx motif is believed to be the active site. However, critical metrics for its catalytic activity, such as active site density and intrinsic turnover frequency, so far lack systematic discussion. In this work, we prepared a set of covalent organic framework (COF)-derived Ni-N-C catalysts, for which the Ni−Nx content could be adjusted by the pyrolysis temperature. The combination of high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure evidenced the presence of Ni single-sites, and quantitative X-ray photoemission addressed the relation between active site density and turnover frequency.
| Original language | English |
|---|---|
| Article number | e202114707 |
| Journal | Angewandte Chemie - International Edition |
| Volume | 61 |
| Issue number | 15 |
| DOIs | |
| State | Published - Apr 4 2022 |
Funding
The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 851441, SELECTCO2. Partial funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy—EXC 2008/1 (UniSysCat)—390540038 is acknowledged. We also acknowledge the financial support from the China Scholarship Council (CSC). We thank VILLUM Centre for the Science of Sustainable Fuels and Chemicals (no. 9455) from VILLUM FONDEN. We thank Christina Eichenauer for assisting in N2 sorption and TGA measurements and Maria Unterweger for conducting XRD measurements. A portion of this research was conducted at ORNL's Center for Nanophase Materials Sciences, a DOE Office of Science User Facility. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA-III and we would like to thank Dr. Vadin Murzin and Dr. Wolfgang Caliebe for assistance in using P64 beamline. Open Access funding enabled and organized by Projekt DEAL. The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 851441, SELECTCO2. Partial funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy—EXC 2008/1 (UniSysCat)—390540038 is acknowledged. We also acknowledge the financial support from the China Scholarship Council (CSC). We thank VILLUM Centre for the Science of Sustainable Fuels and Chemicals (no. 9455) from VILLUM FONDEN. We thank Christina Eichenauer for assisting in N sorption and TGA measurements and Maria Unterweger for conducting XRD measurements. A portion of this research was conducted at ORNL's Center for Nanophase Materials Sciences, a DOE Office of Science User Facility. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA‐III and we would like to thank Dr. Vadin Murzin and Dr. Wolfgang Caliebe for assistance in using P64 beamline. Open Access funding enabled and organized by Projekt DEAL. 2
Keywords
- Active Site Density
- CO2 Reduction
- Covalent Organic Framework
- Single-Site Ni-N-C
- Turnover Frequency