Excited State Calculations of Cu-Doped Anatase TiO2 (101) and (001) Nanofilms

This study was financially supported by Flag-ERA JTC To2Dox project. E.N. and D.B. thank the Latvian Scientific Council grant No. LZP-2021/1-0464 for support. H.B. and S.Z. are thankful for support from the State Program for Scientific Research of Belarus «Photonics and electronics for innovations». Y.-P.L. thanks the M-ERA.NET project “Multiscale computer modelling, synthesis and rational design of photo(electro)catalysts for efficient visible-light-driven seawater splitting” (CatWatSplit) for financial support. The Institute of Solid State Physics, University of Latvia, as the Center of Excellence, has received funding from the European Union’s Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under Grant Agreement No. 739508, project CAMART2. The calculations were performed at the Latvian SuperCluster (LASC), located at the Institute of Solid State Physics, University of Latvia.Excited state calculations are performed to predict the electronic structure and optical absorption characteristics of Cu-doped anatase TiO2 nanofilms, focusing on their (101) and (001) surface terminations. Using model structures that successfully represent the equilibrium positions of deposited Cu atoms on the TiO2 surface, a comprehensive analysis of the absorption spectra for each considered model is made. The proposed modeling reveals phenomena when photogenerated electrons from TiO2 tend to accumulate in the vicinity of the deposited Cu atoms exposed to photon energies surpassing the band gap of TiO2 (approximately 3.2 eV). The crucial transition states that are essential for the creation of potential photocatalytic materials are identified through detailed calculations of the excited states. These insights hold substantial promise for the strategic design of advanced photocatalytic materials. The obtained results provide a base for subsequent analyses, facilitating the determination of heightened surface reactivity, photostimulated water splitting, and antibacterial properties.--//-- This is an open-access article: Lin, Y.-P.; Neilande, E.; Bandarenka, H.; Zavatski, S.; Isakoviča, I.; Piskunov, S.; Bocharov, D.; Kotomin, E.A. Excited State Calculations of Cu-Doped Anatase TiO2 (101) and (001) Nanofilms. Crystals 2024, 14, 247. https://doi.org/10.3390/cryst14030247 published under the CC BY 4.0 licence.Flag-ERA JTC To2Dox project; Latvian Council of Science grant No. LZP-2021/1-0464; State Program for Scientific Research of Belarus «Photonics and electronics for innovations»; M-ERA.NET project CatWatSplit; the Institute of Solid State Physics, University of Latvia, as the Center of Excellence, has received funding from the European Union’s Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under Grant Agreement No. 739508, project CAMART2

3D Silver Dendrites for Single-molecule Imaging by Surface-enhanced Raman Spectroscopy

Discovery of surface-enhanced Raman scattering (SERS) followed by evolution of optical systems and nanoengineering approaches has paved a path to detection of essential organic molecules on solid SERS-active substrates from solutions at concentrations attributed to single-molecule ones, i. e. below 10(-15) M. However, in practical terms confident SERS-imaging of single molecules is still quite a challenge. In present work, we fabricated and comprehensively characterized tightly-packed 3D silver dendrites with prevalent chevron morphology that demonstrated ultrahigh sensitivity as SERS-active substrates resulted in 10(-18) M detection limit. Using these substrates we achieved SERS-imaging of single 5-thio-2-nitrobenzoic acid (TNB) molecule released from the attomolar-concentrated solution of of 5,5 '-dithio-bis-[2-nitrobenzoic acid] (DTNB), which is vital compound for chemical and biomedical analysis. In contrast to generally accepted belief about adsorption of only uniform monomolecular TNB layer on surface of silver nanostructures, we showed formation of a coating constituted by TNB layer and DTNB nanoclusters on the dendrites' surface at 10(-6)-10(-12) M DTNB concentrations confirmed by presence/absence of disulfide bonds signature in the SERS-spectra and by scanning electron microscopy. DTNB concentrations below 10(-14) M resulted in adsorption of TNB molecules in separated spots on the surface of silver nanostructures