Multiphoton ultraviolet upconversion through selectively controllable energy transfer in confined sensitizing sublattices towards improved solar photocatalysis

作者：Liu, Songbin; Huang, Jinshu; Yan, Long; Song, Nan; Zhang, Peng; He, Junshan; Zhou, Bo^*

来源：Journal of Materials Chemistry A, 2021, 9(7): 4007-4017.

DOI：10.1039/d0ta11387e

Multiphoton ultraviolet (UV) upconversion has recently gained remarkable attention because of its promising applications ranging from biomedicine to nanophotonics. However, it is still a challenge to realize intense UV upconversion in conventional lanthanide-doped materials. Herein, we report a mechanistic strategy to achieve the UV upconversion emission by selectively controlling the ionic interactions in a modified core-shell nanostructure through spatial confinement of lanthanide emitters inside a sensitizing lattice. This design ensures the entire surrounding of emitters (e.g., Tm3+, Er3+ and Gd3+) by the sensitizers, which is able to increase the localized excitation energy density and further accelerate the population of intermediate energy levels as well as the higher-lying UV emitting level by sequential energy transfer upconversion processes. 980/808 nm dual-wavelength responsive UV upconversion has also been enabled by incorporating Nd3+ into inert shells. More importantly, the UV upconversion is easily available upon excitation by a commercial 940 nm NIR light-emitting diode (LED), which can be used to expand the spectral response towards improved solar photocatalysis through fabricating a nanocomposite of upconversion nanoparticles/g-C3N4. Our results offer a conceptual model to achieve intense UV emission of lanthanides, showing great promise in frontier fields such as photocatalysis, upconversion lasers, and bioimaging-guided therapeutics.