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Silver-doped zinc oxide nanostructures (Ag/ZnO NSs) with Ag content of 0 wt%, 5 wt%, 10 wt%, and 20 wt% were synthesized using a hydrothermal technique. The prepared nanostructures were annealed at 500 °C for 2 h. The samples were characterized by using scanning electron microscopy, FTIR, X-ray diffraction (XRD), and electrical conductivity. FTIR spectra confirms the presence of hydrogen-related shallow donor defects in the Ag/ZnO NSs, which bind to the oxygen vacancy ($${\text{H}}_{\text{O}}$$ H O ) and consequently plays a significant role in the physicochemical properties of the metal oxide nanostructures. The $${\text{H}}_{\text{O}}$$ H O defects are blended to O- and Zn-polar Ag-doped ZnO NSs, depending on their polarity. XRD results verified that Ag/ZnO NSs have a polycrystalline hexagonal structure. Williamson–Hall methods were used to estimate the microstructural properties of polycrystalline nanostructures. The electrical conductivity increased from 0.60 to 1.10 µS/cm, and the bandgap energy decreased from 3.36 to 3.10 eV by increasing the Ag from 0 wt% up to 20 wt%.

The electrical conductivity (σ) and Seebeck coefficient (S) at temperatures from 40 ◦C to 100 ◦C of melt-processed polypropylene (PP) composites filled with 5 wt.% of industrial-grade carbon nanofibers (CNFs) is investigated. Transmission Electron Microscopy (TEM) of the two Pyrograf® III CNFs (PR 19 LHT XT and PR 24 LHT XT), used in the fabrication of the PP/CNF composites (PP/CNF 19 and PP/CNF 24), reveals that CNFs PR 24 LHT XT show smaller diameters than CNFs PR 19 LHT XT. In addition, this grade (PR 24 LHT XT) presents higher levels of graphitization as deduced by Raman spectroscopy. Despite these structural differences, both Pyrograf® III grades present similar σ (T) and S (T) dependencies, whereby the S shows negative values (n-type character). However, the σ (T) and S (T) of their derivative PP/CNF19 and PP/CNF24 composites are not analogous. In particular, the PP/CNF24 composite shows higher σ at the same content of CNFs. Thus, with an additionally slightly more negative S value, the PP/CNF24 composites present a higher power factor (PF) and figure of merit (zT) than PP/CNF19 composites at 40 ◦C. Moreover, while the σ (T) and S (T) of CNFs PR 19 LHT XT clearly drive the σ (T) and S (T) of its corresponding PP/CNF19 composite, the S (T) of CNFs PR 24 LHT XT does not drive the S (T) observed in their corresponding PP/CNF24 composite. Thus, it is inferred in PP/CNF24 composites an unexpected electron donation (n-type doping) from the PP to the CNFs PR 24 LHT XT, which could be activated when PP/CNF24 composites are subjected to that increase in temperature from 40 ◦C to 100 ◦C. All these findings are supported by theoretical modeling of σ (T) and S (T) with the ultimate aim of understanding the role of this particular type of commercial CNFs on the thermoelectrical properties of their PP/CNF composites., A.J.P. gratefully acknowledges support from FCT-Foundation for Science and Technology by the project UID/CTM/00264/2021 of 2C2T under the COMPETE and FCT/MCTES (PIDDAC) co-financed by FEDER through the PT2020 program and “plurianual” 2020–2023 Project UIDB/00264/2020. C.J.T. acknowledges the funding from FCT/PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023. E.M. acknowledges support from Project ANID PIA Anillo ACT/192023.

Pure ZnO and ZnO–Bi2O3 nanocomposites with 5 wt% and 10 wt% of Bi2O3 content were synthesized using the co-precipitation method. Optical properties such as refractive index (n), extinction coefficient (k), bandgap (Eg), and Urbach energies, as well as the band structure, were determined by modeling the experimental transmittance and reflectance UV–Vis spectra. The deduced bandgap and Urbach energies for pure ZnO (3.758 eV) increase with the increase of the doping degree of Bi2O3 in ZnO–Bi2O3 nanocomposite films. X-ray diffraction and scanning electron microscopy (SEM) was used to study the structural and morphological properties of these nanocomposite films. Pure ZnO and nanocomposites with Bi2O3 exhibit crystalline domains with wurtzite hexagonal structures, and as the doping degree of Bi2O3 increases, the crystallite size decreases. Based on SEM micrographs, the ZnO nanoparticles (NPs) structure shows the presence of aggregation. Moreover, Bi2O3 NPs in the nanocomposite film led to the further aggregation in the form of large rods. The elemental and chemical properties of the nanocomposites were investigated using infrared and energy-dispersive X-ray spectroscopy. The charge transfer process in the studied system is between ZnO and Bi2O3 conduction bands. Density-functional theory (DFT) calculations were performed for ZnO, Bi2O3, and ZnO-Bi2O3 compounds to investigate structural, optical, and electronic properties, being in agreement with the experimental results.

The dissipation of heat generation has been one of the largest obstacles in the design of semiconductor devices and reducing the thermal conductivity is vital for improving thermoelectric efficiency. This work focuses on the Bi doping effect on ZnO, and ZnO:Al thin films produced by magnetron sputtering with thickness varying between 500 and 900 nm. The approach introduces Bi ions, a higher mass element, into the ZnO metal-oxide matrix, to hinder phonon-mediated heat conduction and, consequently, reduce thermal conductivity. Atom probe tomography (APT) was employed to survey Bi doping distribution in ZnO:Al:Bi and ZnO:Bi thin films and to study the morphology of the grain boundaries. The thermal properties of the thin films were measured by frequency-domain thermoreflectance. Based on thermal conductivity results, it is concluded that the doping of ZnO films with Al has a significant effect on thermal conductivity, being reduced from 6.0 W m−1 K−1 in its undoped state to 3.3 W m−1 K−1 for ZnO with ∼3 at.% of Al, mainly due to alloy scattering of phonons in the wurtzite cell. Further doping with Bi contributes to a slight reduction in the thermal conductivity of ZnO:Al.Bi films (2.9 W m−1 K−1), due to grain boundary scattering by Bi/Bi2O3 phases. This result is understood as the confluence of two counteracting effects. On the one hand, the thermal conductivity of the film decreases because Bi, unlike Al, is segregated to grain boundaries and does not substitute Zn in the wurtzite crystal lattice, which is unequivocally demonstrated by APT results. On the other hand, the simultaneous presence of Al and Bi triggers a morphological change with the film's microstructure becoming more columnar. This change in microstructure from 3D island growth in ZnO:Al and ZnO:Bi to a more regular columnar structure in ZnO:Al,Bi limits further reduction in the thermal conductivity., Filipe Correia is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. grant SFRH/BD/111720/2015. Joana Ribeiro is grateful to the FCT, Portugal, for the Ph.D. grant SFRH/BD/147221/2019. Funding is also gratefully acknowledged from FCT/PIDDAC through the Strategic Funds project reference UIDB/04650/2020–2023 and from the Spanish Ministerio de Ciencia e Innovación (MICINN) through grants SEV-2015-0496 (FUNMAT) and CEX2019-000917-S (FUNFUTURE) in the framework of the Spanish Severo Ochoa Centre of Excellence program, and grant PID2020-119777 GB-I00 (THERM2MAIN). This work (proposal ID 2018-020-022469) was carried out with the support of the Karlsruhe Nano Micro Facility (KNMFi, www.knmf.kit.edu), a Helmholtz Research Infrastructure at Karlsruhe Institute of Technology (KIT, www.kit.edu)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

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Antibiotics represent one increasingly harmful type of contaminant of emerging concern in treated and non-treated water. They cause the generation of antibiotic-multiresistant organisms, one of the major challenges in current medicine. Plasmonic-photocatalysis using solar energy represents a promising solution for their removal with low energy consumption. Its successful application requires the improvement of photocatalysts' efficiency under sunlight and the development of robust, durable, and efficient substrates for photocatalysts immobilisation. In this work, hybrid TiO

Surface disinfection currently plays a decisive role in the epidemiological situation caused by the SARS-CoV-2 coronavirus. However, most disinfection products available on the market have a high evaporation rate and only an immediate action and not continuous, creating the need for a high frequency of disinfection. To overcome this limitation, in the present work, poly(methyl methacrylate) (PMMA) microcapsules were developed with an active agent (hydrogen peroxide) encapsulated, which has the ability to inactivate/neutralize the SARS-CoV-2 virus. PMMA-H

Nanomaterials can be game-changers in the arena of sustainable energy production because they may enable highly efficient thermoelectric energy conversion and harvesting. For this purpose, doped thin film oxides have been proven to be promising systems for achieving high thermoelectric performances. In this work, the design, realization, and experimental investigation of the thermo electric properties exhibited by a set of five Al:ZnO thin films with thicknesses of 300 nm and Al doping levels ranging from 2 to 8 at.% are described. Using a multi-technique approach, the main structural and morphological features of the grown thin films are addressed, as well as the electrical and thermoelectrical transport properties. The results show that the samples exhibited a Seebeck coefficient absolute value in the range of 22–33 µV/K, assuming their maximum doping level was 8 at.%, while the samples’ resistivity was decreased below 2 × 10−3 Ohm·cm with a doping level of 3 at.%. The findings shine light on the perspectives of the applications of the metal ZnO thin film technology for thermoelectrics., This research was funded by MIUR-PON, scholarship PhD program “Physics and nano sciences”021/22.“Nanotecnologie per la termoelettricità e l’energy harvesting” (Azione IV.5 “Dottorati su tematiche green”) and by project QUANTEP, INFN CSN5. VB was supported by the project “Brosynano”MICINN-FEDER (PID2019-106820RB-C22). C.T. acknowledges the funding from FCT/PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023. A.M., G.P. acknowledge support by the Italian Ministry of University and Research through PRIN UTFROM N. 20178PZCB5. This work was also partially funded under the National Recovery and Resilience Plan (NRRP), Mission 04 Component 2 Investment 1.5 – NextGenerationEU, Call for tender n. 3277 dated 30/12/2021. Award Number: 0001052 dated 23/06/2022.

The determination of the optical band gap energy ( E g ) is important for optimization of the generation of electron/hole pairs in semiconductor materials under illumination. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) has been largely employed for the study of amorphous and polycrystalline materials. In this paper, the authors demonstrate, step by step, how to use the K-M function and apply it thoroughly to the determination of the E g of TiO2 semiconductor powder (pressed at different thicknesses) from diffuse reflectance spectroscopy (DRS) measurements. For the sample thicknesses 1–4 mm, E g values of 3.12–3.14 eV were obtained. With this work it is envisaged a clarification to the procedure of determination of the E g from the K-M theory and DRS data, since some drawbacks, and misconceptions have been identified in the recent literature. In particular, the widely used practice of determining the E g of a material directly from the K-M function is found to be inadequate.

Synthesized PEO:I2 complex composite films with different I2 concentrations were deposited onto fused silica substrates using a dip-coating method. Incorporation of PEO films with I2 increases the electrical conductivity of the composite, reaching a maximum of 46 mS/cm for 7 wt% I2. The optical and optoelectronic properties of the complex composite films were studied using the transmittance and reflectance spectra in the UV-Vis region. The transmittance of PEO decreases with increasing I2 content. From this study, the optical bandgap energy decreases from 4.42 to 3.28 eV as I2 content increases from 0 to 7 wt%. In addition, the refractive index for PEO films are in the range of 1.66 and 2.00.1H NMR spectra of pure PEO film shows two major peaks at 3.224 ppm and 1.038 ppm, with different widths assigned to the mobile polymer chains in the amorphous phase, whereas the broad component is assigned to the more rigid molecules in the crystalline phase, respectively. By adding I2 to the PEO, both peaks (amorphous and crystal) are shifted to lower NMR frequencies indicating that I2 is acting as a Lewis acid, and PEO is acting as Lewis base. Hence, molecular iodine reacts favorably with PEO molecules through a charge transfer mechanism, and the formation of triiodide ($${\mathrm{I}}_{3}^{-}$$ I 3 - ), the iodite ($${\mathrm{IO}}_{2}^{-}$$ IO 2 - ) anion, $${\mathrm{I}}_{2} \cdot \cdot \cdot \mathrm{ PEO}$$ I 2 · · · PEO and $${\mathrm{I}}_{2}^{+} \cdot \cdot \cdot \mathrm{ PEO}$$ I 2 + · · · PEO complexes. PEO:I2 complex composite films are expected to be suitable for optical, electrical, and optoelectronic applications.

Currently, the direct synthesis of faujasite-type (FAU) zeolites with Si/Al ratios greater than 3 depends on organic or inorganic additives. Here, we report the first additive-free synthesis of faujasite with Si/Al ratios greater than 3 using ultraviolet (UV) light assistance. The obtained zeolite shows excellent catalytic performance comparable to the commercial zeolite Y. published

The focus of this work lies on the production of a multifunctional materials that allows the combination of photocatalysis and adsorption in a unique polymeric substrate. For this purpose, Au/TiO2 and Y2(CO3)3 nanoparticles were immobilised on a poly (vinylidene fluoride hexafluoropropylene), (PVDF-HFP), substrate, and the characterisation of these materials was performed, as well as the pollutant removal efficiency. An efficient TiO2 functionalisation with gold nanoparticles was achieved, endowing these particles with the ability to absorb visible radiation. Concerning the membranes, a favourable porous structure was obtained, with an average pore size of 4 µm, and the nanoparticles immobilisation did not alter the physical and chemical properties of the polymeric membrane. The produced hybrid materials, including both Au/TiO2 and Y2(CO3)3 nanoparticles presented an efficiency of 57% in the degradation of norfloxacin (5 mg/L) under ultraviolet radiation for 120 minutes, 80% under visible radiation for 300 minutes, and 58% in arsenic adsorption for 240 minutes. These membranes represent a new platform for the removal of several pollutants, which may allow their incorporation in more efficient and less energy-consuming water treatment processes and favour water treatment in developing countries with low energy resources., This work was supported by the Portuguese Foundation for Science and Technology (Fundação para a Ciência e a Tecnologia - FCT) in the framework of the strategic project UID/QUI/0686/2020 and UID/FIS/04650/2020 by FEDER funds through the COMPETE 2020-Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941, project PTDC/CTM-ENE/5387/2014, 2020–2023 multiannual funding to Centro de Química Estrutural (project UIDB/00100/2020) and Associate Laboratory for Green Chemistry – LAQV (UIDB/50006/2020 and UIDP/50006/2020). Bruno Santos, H. Salazar and P. Martins thanks FCT for the grants 2020.09630.BD, SFRH/BD/122373/2016, and 2020.02802. CEECIND contract. S.C. thanks FCT for Scientific Employment Stimulus - Institutional Call (CEECINST/00102/2018) contract. Finally, authors acknowledge funding from the Basque Government Industry Department under the ELKARTEK program. The authors also acknowledge the contribution of A. Fidalgo-Marijuan and Victor Sebastian for the TEM micrographs.