Ultrasmall C-TiO2−x nanoparticle/g-C3N4 composite for CO2 photoreduction with high efficiency and selectivity

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2018, Vol.6 (43), p.21596-21604
• Main Authors: Zhou, Jie, Wu, Han, Chun-Yi, Sun, Cheng-Ying, Hu, Xin-Long, Wang, Zhen-Hui, Kang, Zhong-Min, Su
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon monoxide; Carbon nitride; Chemical bonds; Clean energy; Coupling (molecular); Irradiation; Light irradiation; Nanoparticles; Organic chemistry; Oxidation; Photocatalysts; Photochemistry; Photons; Photooxidation; Photoreduction; Protons; Selectivity; Titanium dioxide
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c8ta08091g

The photoreduction of CO2 to CO offers a promising sustainable and clean approach for a global new energy program. Coupling this reductive process with a matched water photo-oxidation pathway is an attractive avenue to accelerate the half-reaction of CO2 reduction. Herein, we propose a three-component photocatalyst design strategy for reducing CO2 to CO coupled with water oxidation via a two-electron/two-step pathway. Employing polyoxotitanium ([Ti17O24(OPri)20]) as a titanium source, ultrasmall TiO2−x nanoparticles coated with ultrathin carbon layers (C-TiO2−x) were fabricated and loaded on to a g-C3N4 matrix through chemical bonding (C-TiO2−x@g-C3N4) for the first time. The optimized C-TiO2−x@g-C3N4 photocatalyst showed a very high activity of 12.30 mmol g−1 (204.96 mmol gTiO2−1) CO generation within 60 h visible-light irradiation, which represents the highest CO production rate to date among the reported TiO2-based materials under similar conditions. The excellent adsorption capability of C-TiO2−x@g-C3N4 for photons, H+ protons, and CO2 molecules together with efficient charge separation and the two-electron/two-step oxidative pathway lead to the high reactivity.