Visible light responsive metalloporphyrin-sensitized TiO 2 nanotube arrays for artificial photosynthesis of methane

• Published in: Reaction chemistry & engineering 2022-03, Vol.7 (4), p.917-928
• Main Authors: Xiao, Tongxin, Chen, Ying, Liang, Yuning
• Format: Article
• Language: English
• ISSN: 2058-9883; 2058-9883
• DOI: 10.1039/D1RE00442E

The conversion of CO 2 and water into valuable chemicals under sunlight irradiation is of great significance for solving the widespread problems of both limited energy sources and global warming. In this work, new artificial photosynthesis was established through a photocatalysis process of reducing CO 2 to CH 4 . A photocatalyst compounded from a porphyrin (metalloporphyrin) and TiO 2 nanotube arrays (TiO 2 NTs) was prepared, and its photocatalytic performance for CO 2 reduction under Xe lamp irradiation was studied. Compared with the pure TiO 2 NTs, the photocatalytic CO 2 reduction activity of metalloporphyrin-sensitized TiO 2 NTs is significantly enhanced. The amount of methane produced with the cobalt tetra(4-carboxyphenyl)porphyrin/TiO 2 NTs (CoTCPP/TiO 2 NTs) photocatalyst is about 5.5 times higher than that produced with TiO 2 NTs alone. The improvement of photocatalytic activity can be ascribed to the enhancement of light absorption ability of CoTCPP/TiO 2 NTs and the inhibition of electron–hole recombination. Furthermore, according to the results of the photocatalytic and photo(electro)chemical experiments, a probable mechanism for the photoreduction of CO 2 over CoTCPP/TiO 2 NTs is presented.