Only when the interfacial charge separation is enhanced and the CO 2 activation is improved, can the heterojunction nanocomposite photocatalyst be brought into full play for the CO 2 reduction reaction (CO 2 RR). Here, Er 3+ single atom composite photocatalysts were successfully constructed based on both the special role of Er 3+ single atoms and the special advantages of the SrTiO 3 :Er 3+ /g-C 3 N 4 heterojunction in the field of photocatalysis for the first time. As we expected, the SrTiO 3 :Er 3+ /g-C 3 N 4 (22.35 and 16.90 μmol g −1 h −1 for CO and CH 4 ) exhibits about 5 times enhancement in visible-light photocatalytic activity compared to pure g-C 3 N 4 (4.60 and 3.40 μmol g −1 h −1 for CO and CH 4 ). In particular, the photocatalytic performance of SrTiO 3 :Er 3+ /g-C 3 N 4 is more than three times higher than that of SrTiO 3 /g-C 3 N 4 . From Er 3+ fluorescence quenching measurements, photoelectrochemical studies, transient PL studies and DFT calculations, it is verified that a small fraction of surface doping of Er 3+ formed Er single-atoms on SrTiO 3 building an energy transfer bridge between the interface of SrTiO 3 and g-C 3 N 4 , resulting in enhanced interfacial charge separation. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and adsorption energy calculations demonstrated that the exposed Er single-atoms outside the interface on SrTiO 3 preferentially activate the adsorbed CO 2 , leading to the high photoactivity for the CO 2 RR. A novel enhanced photocatalytic mechanism was proposed, in which Er single-atoms play dual roles of an energy transfer bridge and activating CO 2 to promote charge separation. This provides new insights and feasible routes to develop highly efficient photocatalytic materials by engineering rare-earth single-atom doping.
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Effect of Carbon Doping on CO 2 ‐Reduction Activity of Single Cobalt Sites in Graphitic Carbon Nitride
Single‐atom catalysts have demonstrated interesting activity in a variety of applications. In this study, we prepared single Co2+sites on graphitic carbon nitride (C3N4), which was doped with carbon for enhanced activity in visible‐light CO2reduction. The synthesized materials were characterized with a variety of techniques, including microscopy, X‐ray powder diffraction, UV‐vis spectroscopy, infrared spectroscopy, photoluminescence spectroscopy, and X‐ray absorption spectroscopy. Doping C3N4with carbon was found to have profound effect on the photocatalytic activity of the single Co2+sites. At relatively low levels, carbon doping enhanced the photoresponse of C3N4in the visible region and improved charge separation upon photoactivation, thereby enhancing the photocatalytic activity. High levels of carbon doping were found to be detrimental to the photocatalytic activity of the single Co2+sites by altering the structure of C3N4and generating defect sites responsible for charge recombination.
more » « less- NSF-PAR ID:
- 10250173
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemNanoMat
- Volume:
- 7
- Issue:
- 9
- ISSN:
- 2199-692X
- Page Range / eLocation ID:
- p. 1051-1056
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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