COPPER – BASED SILICATES: SYNTHESIS AND OPTOELECTRONIC PROPERTIES

Alkaline earth copper silicates with the general formula ACuSi₄O₁₀ (where A = Ca2+ and Ba2+) represent a family of materials known since antiquity.[1] In particular, CaCuSi₄O₁₀ and BaCuSi₄O₁₀ traced back in 2500 BC and 1200 BC, and are known as Egyptian blue and Han blue, respectively; they are characterized by an intense blue color and high stability over time.[2] Besides historical interest, the peculiar layered crystalline structure and their emission in the near infrared region (NIR) makes them interesting new materials for optoelectronic applications.[3] The chromophore group is characterized by a [CuO4] in a square planar geometry surrounding by [SiO₄] tetrahedra.[4] Recent studies have demonstrated the possibility of obtaining them in nanometric dimensions through exfoliation. This opportunity opens a new class of two-dimensional nanomaterials with potential applications in the field of biomedical imaging, solar light-to-electricity conversion devices, and IR light-emitting devices, and telecommunications.[5] Herein, we show our recent results on the preparation of 2D nanosheets based on the aforementioned compounds and the SrCuSi4O10. Playing with the exfoliation conditions (e.g. temperature, solvents, surfactants) it is possible to govern the exfoliation processes. Moreover, we tried the first attempt synthesis of alkaline earth copper nano-silicates through a bottom-up strategy, following hydrothermal or colloidal synthesis. [1] P. AM Triolo et al. Archaeol Anthropol Sci 11, 5001–5008 (2019). [2] H. Berke et al. Chemical Society Reviews , 2007, 36.1: 15-30. [3] A. Martinelli et al Chem. Mater. 2023, 35, 22, 9572–9580 [4] EM. Hughes et al. An. Quim. Int. Ed. 1997, 93, 233– 236 [5] D. Johnson et al. J. Am. Chem. Soc. 2013, 135, 5, 1677–1679