Abstract
Metal-organic framework (MOF) materials provide an excellent platform to fabricate single-atom catalysts due to their structural diversity, intrinsic porosity, and designable functionality. However, the unambiguous identification of atomically dispersed metal sites and the elucidation of their role in catalysis are challenging due to limited methods of characterization and lack of direct structural information. Here, we report a comprehensive investigation of the structure and the role of atomically dispersed copper sites in UiO-66 for the catalytic reduction of NO2 at ambient temperature. The atomic dispersion of copper sites on UiO-66 is confirmed by high-angle annular dark-field scanning transmission electron microscopy, electron paramagnetic resonance spectroscopy, and inelastic neutron scattering, and their location is identified by neutron powder diffraction and solid-state nuclear magnetic resonance spectroscopy. The Cu/UiO-66 catalyst exhibits superior catalytic performance for the reduction of NO2 at 25 °C without the use of reductants. A selectivity of 88% for the formation of N2 at a 97% conversion of NO2 with a lifetime of >50 h and an unprecedented turnover frequency of 6.1 h-1 is achieved under nonthermal plasma activation. In situ and operando infrared, solid-state NMR, and EPR spectroscopy reveal the critical role of copper sites in the adsorption and activation of NO2 molecules, with the formation of {Cu(I)···NO} and {Cu···NO2} adducts promoting the conversion of NO2 to N2. This study will inspire the further design and study of new efficient single-atom catalysts for NO2 abatement via detailed unravelling of their role in catalysis.
| Original language | English |
|---|---|
| Pages (from-to) | 10977-10985 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 143 |
| Issue number | 29 |
| DOIs | |
| State | Published - Jul 28 2021 |
Funding
The authors would like to thank the EPSRC (EP/I011870), the Royal Society and the University of Manchester for funding, and the EPSRC for funding of the EPSRC National EPR Facility at Manchester. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 742401, NANOCHEM). This work was supported by the Henry Royce Institute for Advanced Materials, funded through EPSRC grants EP/R00661 X/1, EP/S019367/1, EP/P025021/1, and EP/P025498/1. The authors are grateful to the STFC/ISIS Facility for access to Beamlines TOSCA and WISH. The UK 850 MHz solid-state NMR Facility used in this research was funded by the EPSRC and BBSRC (contract reference EP/T015063/1), as well as the University of Warwick including via part funding through Birmingham Science City Advanced Materials Projects 1 and 2 supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF). Collaborative assistance from the 850 MHz Facility Manager (Dinu Iuga, University of Warwick) is acknowledged. A.M.S. was supported by the Royal Society Newton International Fellowship. Y.M. acknowledges financial support from the China Scholarship Council. Computing resources for neutron data analysis were made available through the VirtuES and the ICE-MAN projects, funded by Laboratory Directed Research and Development program and Compute and Data Environment for Science (CADES) at ORNL.
| Funders | Funder number |
|---|---|
| Birmingham Science City Advanced Materials Projects 1 | |
| Compute and Data Environment for Science | |
| Laboratory Directed Research and Development | |
| Horizon 2020 Framework Programme | 742401 |
| Henry Royce Institute | EP/R00661 X/1, EP/S019367/1, EP/P025021/1, EP/P025498/1 |
| Engineering and Physical Sciences Research Council | EP/I011870 |
| Biotechnology and Biological Sciences Research Council | EP/T015063/1 |
| Royal Society | |
| University of Warwick | |
| University of Manchester | |
| European Research Council | |
| China Scholarship Council | |
| European Regional Development Fund |