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Improving the low charge separation efficiency, poor light absorption capacity, and insufficient active sites of photocatalysts are the important challenges for CO 2 photoreduction. In this study, a Mo modified InOOH/In(OH) 3 heterojunction with enhanced CO 2 reduction efficiency was synthesized in situ by using an In(OH) 3 monatomic lamellar material with isolated In atom sites exposed on its surface. And bandgap tuning via the energy levels formed by Mo doping and vacancy defect engineering can simultaneously improve visible light absorption and photogenerated charge separation. The results of experimental characterization and DFT calculation show that the Mo impurity energy levels, O defect energy levels, and surface Mo atoms existing in the InOOH phase can act as an electron transfer ladder in cooperation with the In defect energy levels in the In(OH) 3 phase, thereby promoting electron transfer between heterogeneous interfaces. Under visible light irradiation, the evolution rates of CH 4 and CO of the Mo modified InOOH/In(OH) 3 photocatalyst are more than ∼11 and ∼8 times higher than those of InOOH, respectively. This work provides new insights into the design of the CO 2 photoreduction platform through a collaborative strategy of bandgap tuning, transition metal doping, and heterostructure construction.
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Dual functions of CO 2 molecular activation and 4f levels as electron transport bridges in erbium single atom composite photocatalysts therefore enhancing visible-light photoactivities
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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- Award ID(s):
- 1945558
- PAR ID:
- 10317152
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 9
- Issue:
- 28
- ISSN:
- 2050-7488
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1039/D1TA02926F
