Design of an alkaline pyridyl acceptor-based calix[4]arene dye and synthesis of stable calixarene–TiO 2 porous hybrid materials for efficient photocatalysis

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-05, Vol.8 (18), p.8883-8891
• Main Authors: Zhong, Yu-Hui, Lei, Yang, Huang, Jian-Feng, Xiao, Li-Min, Chen, Xin-Lun, Luo, Teng, Qin, Su, Guo, Jing, Liu, Jun-Min
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D0TA00754D

A porous organic–inorganic hybrid material consisting of calix[4]arene dye C4BTP with pyridine as an acceptor and titanium dioxide, denoted as C4BTP –TiO 2 , has been prepared by a facile sol–gel method. The C4BTP –TiO 2 materials show expandable photocatalytic activities for H 2 evolution from water and CO 2 reduction to CO when they are loaded with Pt nanoparticles or rhenium complex ReCl(bpy) (CO) 3 ( ReP ) as co-catalysts, respectively. The optimized Pt/ C4BTP –TiO 2 (5.0 wt%) catalyst exhibits a high H 2 production activity (11.99 mmol g −1 h −1 based on catalyst mass) and excellent recyclable durability (a turnover number of 12 981 within 50 h after 10 rounds) under visible-light ( λ > 420 nm), presenting one of the best performances among all the heterogeneous photocatalytic systems based on metal-free sensitizers. As a contrast, the surface sensitized catalyst Pt/gel-TiO 2 / C4BTP only shows far lower activities than hybrid Pt/ C4BTP –TiO 2 under the same conditions. In addition, the optimized ReP / C4BTP –TiO 2 (5.0 wt%) catalyst obtained by loading ReP exhibits a selective photoactivity for CO 2 reduction to CO, giving a turnover number of 112 after 25 h of visible-light irradiation. The good photoactivity and durability of the as-prepared hybrid materials can be attributed to the firm Ti–N linkage and efficient electron transfer between metal-free dye C4BTP and the substrate TiO 2 , while the alkaline-stable Ti–N bond improves the stability of the photocatalysts under basic aqueous conditions. This study offers a good example for the design and preparation of stable organic/inorganic hybrid materials applied in solar energy-solar fuel conversion.