Defect-Driven Dynamics in Gas-Phase Photocatalytic CO₂ Conversion to Solar Fuels Using Ti³⁺/Ti⁴⁺ Containing TiO₂ and Nonstoichiometric Ag₂S Nanowires
Creators
-
1.
Daegu Gyeongbuk Institute of Science and Technology
-
2.
California Institute of Technology
Abstract
We studied CO2 photoreduction on nonstoichiometric surface photocatalysts using a comprehensive approach combining materials design, advanced spectroscopy, and Quantum Mechanics (QM) calculations. We developed a direct Z-scheme heterostructure, A-TiO2/Ag2S NWs, composed of amorphous TiO2 and nonstoichiometric Ag2S nanowires. This structure promotes defect-rich characteristics and a strong internal electric field (IEF), enhancing charge separation and minimizing electron–hole recombination. Employing in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and QM-simulated IR spectra revealed the CO2-to-CH4 conversion mechanism which involves H2COH* intermediate. Ti3+/Ti4+ and Ag+ defect environments were precisely characterized through X-ray photoelectron spectroscopy (XPS) and in situ extended X-ray absorption fine structure (EXAFS). Under concentrated solar illumination, this heterostructure achieved a CH4 production rate of 30.31 μmol/g, a 5-fold enhancement over conventional 1-sun conditions. These findings provide valuable insights into solar-driven fuel synthesis through targeted defect engineering and strategic heterostructure design.
Copyright and License
© 2025 American Chemical Society.
Acknowledgement
The authors acknowledge financial support from the Ministry of Science and ICT in Korea (2021R1A2C2009459). W.A.G. received support from the Liquid Sunlight Alliance, which is supported by the US Department of Energy (Fuels from Sunlight Hub, Office of Basic Energy Sciences, Office of Science) under award number DE-SC0021266. The EXAFS experiments were conducted at the BL10C beamline in the Pohang Accelerator Laboratory . This work used Stampede3 at the Texas Advanced Computing Center through allocation DMR160114 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by the National Science Foundation grants 2138259, 2138286, 2138307, 2137603, and 2138296.
Contributions
N.S.P. and S.K. contributed equally to this work. S.I. conceived the idea and supervised and directed the project. N.S.P. designed the experimental studies, performed the experiments, and analyzed the data. S.K. performed the QM calculations and analyzed the DFT data. S.I., W.A.G., N.S.P., and S.K. wrote the manuscript. C.B.H., J.L., E.G., H.K., and D.K. conducted the formal analysis. All authors discussed the results and commented on the paper.
Supplemental Material
Detailed experimental procedures, characterization data, XAFS fitting, and additional DFT results (PDF)
Files
cs5c05258_si_001.pdf
Additional details
Funding
- Ministry of Science and ICT
- 2021R1A2C2009459
- United States Department of Energy
- DE-SC0021266
- National Science Foundation
- 2138259
- National Science Foundation
- 2138286
- National Science Foundation
- 2138307
- National Science Foundation
- 2137603
- National Science Foundation
- 2138296
Dates
- Submitted
-
2025-07-28
- Accepted
-
2025-10-10
- Available
-
2025-10-23Published online
Caltech Custom Metadata
- Caltech groups
- Division of Chemistry and Chemical Engineering (CCE) , Liquid Sunlight Alliance , Materials and Process Simulation Center
- Publication Status
- Published