CaF₂-Based Near-Infrared Photocatalyst Using the Multifunctional CaTiO₃ Precursors as the Calcium Source

Abstract

Multistage formation of fluoride upconversion agents from the related-semiconductor precursors provides a promising route for the fabrication of near-infrared (NIR) photocatalysts with high photocatalytic activities. Herein, the cotton templated CaTiO3 "semiconduction" precursors (C-CaTiO3) were used to synthesize the NIR photocatalyst of Er3+/Tm3+/Yb3+-(CaTiO3/CaF2/TiO2) (C-ETYCCT), and the functions of the Ca2+ source for CaF2 and the heterostructure formations were displayed by C-CaTiO3. The generated CaF2 acted as the host material for the lanthanide ions, and the heterostructures were constructed among anatase, rutile, and the remaining CaTiO3. The induced oxygen vacancies and Ti3+ ions enabled the samples to utilize most of the upconversion luminescence for photocatalysis. The NIR driven degradation rate of methyl orange (MO) over C-ETYCCT reached 52.34%, which was 1.6 and 2.5 times higher than those of Er3+/Tm3+/Yb3+-(CaTiO3/TiO2) (C-ETYCT) and Er3+/Tm3+/Yb3+-(CaTiO3/CaF2) (C-ETYCC), respectively. The degradation rates of MO and salicylic acid over C-ETYCCT with UV-vis-NIR light irradiation were also much higher than those of other samples, which were mainly results of the contributions of its high upconversion luminescence and the efficient electron-hole pair separation.

Transparent CaF2 surface crystallized CaO–2B2O3 glass possessing efficient photocatalytic and antibacterial properties

“…As the surface areas of all samples were same (2 cm 2 ), so the photocatalytic activity of etched samples was mainly due to the presence of CaF 2 crystals in them. CaF 2 has already reported having photocatalytic activity . The hydrophilic nature of etched samples helped in giving more contact time between dye and glass sample, due to which the surface photocatalysis reactions occurred for a longer time.…”

“…Also, the fabrication of bigger panels of glass is possible, due to which these glass‐ceramics can be easily used in practical applications . Recently, CaF 2 material has gained attention due to its promising antibacterial properties and photocatalytic behavior . CaF 2 crystallization in glasses evolved as an emerging area.…”

Effect of Cupric Salts (Cu (NO3)2, CuSO4, Cu(CH3COO)2) on Cu2(OH)PO4 Morphology for Photocatalytic Degradation of 2,4-dichlorophenol under Near-infrared light irradiation

“…However, due to the wide band gaps of the semiconductor photocatalysts, a large part of solar energy cannot be utilized, especially the near-infrared (NIR) region, which accounts for about 44% of the incoming solar energy 4 . Over the past 30 years, the search for near-infrared light photocatalysts has focused mainly on upconversion luminescence of rare earth materials [5][6][7] . The rare earth materials can transfer near-infrared light to UV or visible light active photocatalysts to generate the strongly oxidative holes and reductive electrons 8 .…”

Broadband NIR photoelectronic performance for sunlight‐induced photocurrent from (NaYF4:Yb‐Er)/BiOI hybrid films

“…In these UC‐PV designs, UC materials convert a certain wavelength of NIR light to visible emission which is then absorbed by the PV device, resulting in the generation of additional photoelectrons contributing to enhancement of efficiency. Among RE ions, Er 3+ is an ideal choice for UC materials because of its abundant energy cascades of f–f transitions and NaYF 4 is widely regarded as the best host due to its chemical stability and high UC efficiency . Usually, the dominating UC emission converted from NIR light by Er‐doped NaYF 4 is in the visible region.…”

“…Among RE ions, Er 3+ is an ideal choice for UC materials because of its abundant energy cascades of f-f transitions and NaYF 4 is widely regarded as the best host due to its chemical stability and high UC efficiency. [18][19][20][21] Usually, the dominating UC emission converted from NIR light by Er-doped NaYF 4 is in the visible region. A suitable semiconductor used in such hybrid solar cell should have a small bandgap such that most visible emissions can be absorbed.…”