Engineering high-coordinated cerium single-atom sites on carbon nitride nanosheets for efficient photocatalytic amine oxidation and water splitting into hydrogen

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-04, Vol.462, p.142084, Article 142084
• Main Authors: Sun, Dan, Chen, Yajie, Yu, Xinyan, Yin, Yuejia, Tian, Guohui
• Format: Article
• Language: English
• Subjects: Amine oxidation; Carbon nitride; Cerium single atom; Hydrogen evolution; Photocatalysis
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.142084

[Display omitted] •A single-atom catalyst with atomically dispersed Ce on C3N4 nanosheets was fabricated.•High-coordinated Ce single atom (Ce-N4/O6) was proved by experimental and theoretical evidences.•The Ce-N4/O6 can greatly improve charge separation and photoinduced electron lifetime.•The catalyst exhibits high photocatalytic amine oxidation and hydrogen evolution performances. Developing highly-active rare-earth single atom photocatalysts have attracted extensive attention due to their excellent catalytic properties. Herein, we prepared a single-atom Ce-SA-C3N4 catalyst composed of atomically dispersed rare-earth cerium (Ce) on C3N4 nanosheets by the pyrolysis of cerium-incorporated layered precursor. The atomic distribution and high-coordinated environment of Ce sites were disclosed by aberration-corrected scanning transmission electron microscopy, electron energy-loss spectra, X-ray absorption spectroscopy, and theoretical calculations. In Ce-SA-C3N4, Ce single atoms are coordinated by four N atoms and six O atoms (Ce-N4/O6). The cooperation of single-atom Ce-N4/O6 active sites in C3N4 nanosheets tunes the electronic structure and the surface trap states, resulting in accelerated charge transfer/separation and extended lifetime of photoinduced electrons. Meanwhile, the high-coordinated Ce-N4/O6 active sites could promote the production of superoxide radicals (•O2−) and C = N bond, thus, the optimized single-atom Ce-SA-C3N4 photocatalyst exhibits highly efficient photocatalytic oxidation of amines under visible light irradiation. Furthermore, the fabricated single-atom Ce-SA-C3N4 photocatalysts are applied to split water into hydrogen, producing the maximum hydrogen yield of 33.5 mmol h−1 g−1. The apparent quantum efficiency for hydrogen evolution achieves 32.6% at 420 nm. This study provides a guideline for rationally designing efficient high-coordinated rare-earth single-atom active sites for efficient solar energy conversion and utilization.