Efficient CO2 reduction over a Ru-pincer complex/TiO2 hybrid photocatalyst via direct Z-scheme mechanism?

Catalysis Science & Technology Pub Date: 2022-01-17 DOI: 10.1039/D1CY01840J

Abstract

Solar-driven CO2 conversion to hydrocarbon fuels is a feasible way to solve the increasingly serious energy problem and greenhouse effect. Herein, we fabricate a novel hybrid photocatalyst for CO2 reduction reaction (CO2RR) by immobilizing the Ru-pincer complex [Ru(N3)(ONO)] on TiO2 nanoparticles. The resultant Ru(N3)(ONO)/TiO2 hybrid photocatalyst achieves maximum CO/CH4 yields of 122.9/12.4 μmol g?1 h?1, corresponding to an overall photoactivity of 344.8 μmol g?1 h?1, which is ～20.0 times higher than that of pristine TiO2 nanoparticles. The characterization results of quasi in situ X-ray photoelectron spectroscopy, reactive oxygen species quantification experiment, and femtosecond transient absorption spectroscopy demonstrate that a direct Z-scheme charge transfer mechanism proceeds in the hybrid material, in which the two components can be excited, and the photoexcited electrons of TiO2 nanoparticles combine with the holes of the Ru(N3)(ONO) complex at their interface. In this Z-scheme hybrid photocatalyst, the Ru-pincer complex is a rare example of both the photoabsorber and active unit for catalyzing CO2RR, and the high oxidation capacity of the holes in the TiO2 nanoparticles and the high reduction ability of the electrons in the Ru(N3)(ONO) complex can be maintained, thus significantly boosting the CO2RR activity. These results demonstrate that the hybridization of the semiconductor with the Ru-based complex would be an effective strategy for artificial photosynthesis with high-performance solar-driven CO2 conversion.

Graphical abstract: Efficient CO2 reduction over a Ru-pincer complex/TiO2 hybrid photocatalyst via direct Z-scheme mechanism
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