In-situ synthesized porphyrin polymer/TiO2 composites as high-performance Z-scheme photocatalysts for CO2 conversion

The promising photocatalytic conversion of CO2 into valuable fuel promotes the development of photocatalyst through various methods. In this work, TiO2 nanoparticle was composited with covalent porphyrin polymers (COP-Ps) to fabricate composite photocatalysts. The resultant COP-Ps/TiO2 composites by in situ hydrothermal method exhibit much improved photocatalytic activity for the conversion of CO2 into CO relative to two components, and it is attributable to improved charge transfer between two moieties led by strong interaction. Especially, TiO2 is composited more evenly with the sulfonated hollow COP-P (sh-COP-P). The resultant composite sh-COP-P/TiO2 performs best with a CO production rate of 5.70 mu mol.g(-1).h(-1) which is approximately 20.4 times as high as that of pure TiO2 and 2.3 times of sh-COP-P polymer. For comparison, the simple physical mixture of sh-COP-P and TiO2 (sm-sh-COP-P/TiO2) was fabricated, and it performs more badly due to poor mixing uniformity. A Z-scheme photocatalytic mechanism was proposed for sh-COP-P/TiO2 composite on the basis of energy band analysis and hydroxyl radical test. This study provides a new in situ strategy to fabricate organic polymer/metal oxide composites of high photocatalytic activity for CO2 reduction. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

In this study, TiO2 nanoparticles were composited with covalent porphyrin polymers to enhance the photocatalytic activity of CO2 conversion. The composite of sulfonated hollow COP-P and TiO2 showed the best performance with a CO production rate of 5.70 μmol.g(-1).h(-1). A Z-scheme photocatalytic mechanism was proposed to explain the working principle of the composite material.