A research group from the Chinese Academy of Sciences has actually considerably improved visible light absorption in Ce/TiO2 by doping cerium in the TiO2 lattice, resulting in a high photocurrent density and much better separation efficiency of photogenerated electrons and holes. This study presents an useful method for establishing effective noticeable light-activated unusual earth-doped photocatalysts.
Visible Light Absorption of Titanium Dioxide Through Cerium Synchronous Doping in Anatase
The introduction of uncommon earth elements into TiO2 can effectively improve the electron-hole separation of TiO2 and lengthen the noticeable light action of TiO2.
Cerium (Ce) reveals variable valence states Ce3+/ Ce4+ with various electronic structures (4f15d0 and 4f05d0, respectively) among uncommon earth elements, which easily form oxygen jobs. Ce element with distinct electronic structure can be utilized to customize semiconductor photocatalysts to improve their photocatalytic efficiency.
In a study released in the journal Molecule, the research study group led by Prof. LU Canzhong from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences, reported the noticeable light absorption of Ce/TiO2.
The scientists accomplished synchronised doping of Ce in the TiO2 lattice using an easy sol-gel technique which attained Ce concurrent doping in the lattice of TiO2. They observed morphology and structure of the pure TiO2, Ce-doped TiO2 (Ce/TiO2), and CeO2-mixed TiO2 (CeO2-TiO2) samples by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Ce/TiO2 reveals visible light absorption up to 500 nm, while pure TiO2 reveals no obvious reaction in the visible area.
The scientists achieved simultaneous doping of Ce in the TiO2 lattice using a basic sol-gel method which accomplished Ce concurrent doping in the lattice of TiO2. They observed morphology and structure of the pure TiO2, Ce-doped TiO2 (Ce/TiO2), and CeO2-mixed TiO2 (CeO2-TiO2) samples by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). They found that Ce doping in the lattice of anatase TiO2 resulted in a smaller grain size of the sample.
Besides, the scientists exposed the high photocurrent density (10.9 µA × cm-2) of Ce/TiO2 by direct sweep voltammetry (LSV) test, which is 2.5 times that of common TiO2 product (4.3 µA × cm-2). They examined the light absorption variety of Ce/TiO2 using event photo-to-current effectiveness (IPCE) test. Ce/TiO2 reveals visible light absorption approximately 500 nm, while pure TiO2 reveals no apparent action in the noticeable region.
The researchers unveiled that the electron-trapping centers formed by Ce doping into the TiO2 lattice improved the separation performance of photogenerated electrons and holes. The narrow bandgap of Ce-doped TiO2 showed excellent visible light absorption and photocurrent action. Due to the Ce doping, the Ce/TiO2 samples achieved high photocurrent density and event photon present efficiency (IPCE).
This study offers an useful method and an important recommendation for the preparation and understanding of extremely effective visible light-activated uncommon earth-doped photocatalysts.
Reference: “Cerium Synchronous Doping in Anatase for Enhanced Photocatalytic Hydrogen Production from Ethanol-Water Mixtures” by Mei-Hong Tong, Yan-Xin Chen, Tian-Ming Wang, Shi-Wei Lin, Gen Li, Qian-Qian Zhou, Rui Chen, Xia Jiang, Hong-Gang Liao and Can-Zhong Lu, 7 March 2023, Molecule.DOI: 10.3390/ molecules28062433.