Modulating interfacial charges in CTF-based metal-insulator-semiconductor promotes selective CO2 reduction to CH4

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 482; p. 149027
• Main Authors: Chen, Qiaoshan, Chen, Yueling, Yu, Mingfei, Xu, Bin, Wu, Houyi, Li, Liuyi, Bi, Jinhong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2024
• Subjects: Carbon dioxide reduction; Covalent triazine-based frameworks; Metal–insulator-semiconductor; Methane evolution; Visible-light photocatalysis; Methane evolution; Carbon dioxide reduction; Metal–insulator-semiconductor; Visible-light photocatalysis; Covalent triazine-based frameworks
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2024.149027

[Display omitted] •Excellent activity and selectivity of CO2-to-CH4 conversion is realized by MIS.•The ultrathin insulator layer significantly expedites the interfacial electrons tunneling.•The MIS promotes rate-determining step from *COOH to *CO to produce CH4. A metal–insulator-semiconductor (MIS) ternary photo-system was intricately crafted through precise amalgamation polyvinylpyrrolidone (PVP)-capped metal Cu with typical covalent triazine framework CTF-1 via electrostatic self-assembly. The 2 % Cu-PVP-CTF exhibited an impressive CH4 yield of 80.7 μmol·g−1·h−1 with selectivity of 96.8 % under visible light, representing a 2.3-fold and 112-fold improvement over Schottky-type Cu-CTF and pristine CTF-1, respectively. In-situ XPS and VASP-diff calculations unfolded that the ultrathin PVP insulating layer significantly expedited interfacial charges tunneling, corroborated by smaller lifetime τ2 determined via femtosecond transient absorption spectroscopy. The intermediates of paramount importance in CO2 reduction like *COOH and *HCHO were meticulously monitored by in-situ Fourier infrared spectroscopy. DFT calculations elucidated that Cu-PVP-CTF was notably more adept at facillitating the rate-determining step (*COOH → *CO) to produce CH4 than Cu-CTF. This work tamps the groundwork for conceptional roadmap in designing novel MIS photo-system for CO2 conversion.