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| 2. |
- Concina, Isabella
(författare)
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An Old Material for a New World: Prussian Blue and Its Analogues as Catalysts for Modern Needs
- 2024
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Ingår i: Inorganics. - : Multidisciplinary Digital Publishing Institute (MDPI). - 2304-6740. ; 12:4
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Forskningsöversikt (refereegranskat)abstract
- Prussian blue analogues (PBAs) have recently emerged as effective materials in different functional applications, ranging from energy storage to electrochemical water splitting, thence to more “traditional” heterogeneous catalysis. Their versatility is due to their open framework, compositional variety, and fast and efficient internal charge exchange, coupled with a self-healing ability that makes them unique. This review paper presents and discusses the findings of the last decade in the field of the catalytic and photocatalytic application of PBAs in water remediation (via the degradation of organic pollutants and heavy metal removal) and the catalytic oxidation of organics and production or organic intermediates for industrial synthesis. Analysis of the catalytic processes is approached from a critical perspective, highlighting both the achievements of the research community and the limits still affecting this field.
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| 3. |
- Di Mauro, Alessandro, et al.
(författare)
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Visible Light Photodegradation of Dyes and Paracetamol by Direct Sensitization Mechanism onto Metallic MoO2 Nanocrystals
- 2021
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Ingår i: Journal of Photochemistry and Photobiology A. - : Elsevier. - 1010-6030 .- 1873-2666. ; 413
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Tidskriftsartikel (refereegranskat)abstract
- MoO2 nanocrystals were prepared by solvothermal treatment of a Mo chloromethoxide at 250 °C in oleic acid. The monoclinic MoO2 phase, with a mean crystallite size of 29 nm, formed through reduction of molybdenum bronzes. The as-prepared MoO2 nanocrystals were free from organics, allowing their use in photodegradation tests of organic pollutants (methylene blue, rhodamine B, paracetamol), without any preliminary purification treatment of the nanocrystals. It was found that MoO2 was an efficient adsorbent of methylene blue (43 mg g-1 for 1.5 × 10−4 M concentration) in the dark and an efficient photodegradation catalyst under visible light (all methylene blue removed from the solution after 240 min). From the analysis of the combined photodegradation tests of rhodamine B and paracetamol, it was clarified that direct sensitization was responsible for photodegradation. This finding was related to the work function value of metallic MoO2, placed at more negative values if compared with other metallic materials.
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| 4. |
- Dobryden, Illia, et al.
(författare)
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Nanoscale characterization of an all-oxide core-shell nanorod heterojunction using intermodulation atomic force microscopy (AFM) methods
- 2021
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 3:15, s. 4388-4394
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Tidskriftsartikel (refereegranskat)abstract
- The electrical properties of an all-oxide core-shell ZnO-Co3O4nanorod heterojunction were studied in the dark and under UV-vis illumination. The contact potential difference and current distribution maps were obtained utilizing new methods in dynamic multifrequency atomic force microscopy (AFM) such as electrostatic and conductive intermodulation AFM. Light irradiation modified the electrical properties of the nanorod heterojunction. The new techniques are able to follow the instantaneous local variation of the photocurrent, giving a two-dimensional (2D) map of the current-voltage curves and correlating the electrical and morphological features of the heterostructured core-shell nanorods.
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| 5. |
- Epifani, Mauro, et al.
(författare)
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Rhodium as efficient additive for boosting acetone sensing by TiO2 nanocrystals : Beyond the classical view of noble metal additives
- 2020
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 319
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Tidskriftsartikel (refereegranskat)abstract
- Anatase TiO2 nanocrystals were prepared by solvothermal synthesis and modified by in- situ generated Rh nanoparticles, with a starting nominal Rh:Ti atomic concentration of 0.01 and 0.05. After heat-treatment at 400 °C the TiO2 host was still in the anatase crystallographic phase, embedding Rh nanoparticles homogeneously distributed and whose surface had been oxidized to Rh2O3, as established by X-ray diffraction, Transmission Electron Microscopy and X-ray Photoelectron spectroscopy. Moreover, Rh seemed also homogeneously distributed in elemental form or as Rh2O3 nanoclusters. The acetone sensing properties of the resulting materials were enhanced by Rh addition, featuring a response increase of one order of magnitude at the best operating temperature of 300 °C. Moreover, Rh addition enlarged the detection range down to 10 ppm whereas pure TiO2 was not able of giving an appreciable response already at a concentration as high as 50 ppm. From the sensing data, the enhancement of the sensor response was attributed to the finely dispersed Rh species and not to the oxidized Rh nanocrystals.
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| 6. |
- Gilzad Kohan, Mojtaba, et al.
(författare)
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All-oxide solar cells
- 2020
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Ingår i: Solar Cells and Light Management. - : Elsevier. ; , s. 229-246
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- One of the most intensively investigated directions in the field of photovoltaics is the development of technologies able to provide vacuum-free and low-cost solar cells with decent efficiency, based on earth-abundant and environmentally friendly materials. Solar cells based on oxide materials are a promising candidate for the purpose, being most of the investigated oxides comparatively more stable than most of solar cell technologies alternative to silicon, and composed of harmless materials. While oxides can exhibit high extinction coefficient in the visible and near-infrared spectral region, guaranteeing full absorption of sunlight, the main factor limiting efficiency in such kind of p–n junction devices is the low hole mobility in the p-type oxide, which represents the main challenge to be overcome to make this technology competitive. This chapter illustrates the latest results in the field, including integration of nanowire geometries as viable solution toward fast charge transport and collection.
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| 7. |
- Gilzad Kohan, Mojtaba, et al.
(författare)
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In-depth photocarrier dynamics in a barrier variable iron-oxide and vertically aligned reduced-graphene oxide composite
- 2022
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Ingår i: NPJ 2D MATERIALS AND APPLICATIONS. - : Springer Nature. - 2397-7132. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- A key requirement for semiconductors operating in light-harvesting devices, is to efficiently convert the absorbed photons to electronic excitations while accommodating low loss pathways for the photogenerated carrier’s transport. The quality of this process corresponds to different relaxation phenomena, yet primarily it corresponds to minimized thermalization of photoexcited carriers and maximum transfer of electron-hole pairs in the bulk of semiconductor. However, several semiconductors, while providing a suitable platform for light-harvesting applications, pose intrinsic low carrier diffusion length of photoexcited carriers. Here we report a system based on a vertical network of reduced graphene oxide (rGO) embedded in a thin-film structure of iron oxide semiconductor, intended to exploit fast electron transport in rGO to increase the photoexcited carrier transfer from the bulk of the semiconductor to rGO and then to the external circuit. Using intermodulation conductive force microscopy, we locally monitored the fluctuation of current output, which is the prime indication of successful charge transfer from photoexcited semiconductor to rGO and efficient charge collection from the bulk of the semiconductor. We reveal the fundamental properties of vertical rGO and semiconductor junction in light-harvesting systems that enable the design of new promising materials for broad-band optical applications.
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| 8. |
- Gilzad Kohan, Mojtaba, et al.
(författare)
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Optical field coupling in ZnO nanorods decorated with silver plasmonic nanoparticles
- 2021
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 9:43, s. 15452-15462
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Tidskriftsartikel (refereegranskat)abstract
- Characterizing carrier redistribution due to optical field modulation in a plasmonic hot-electron/semiconductor junction can be used to raise the framework for harnessing the carrier decay of plasmonic metals in more efficient conversion systems. In this work we comprehensively studied the carrier redistribution mechanisms of a 1-dimensional (1D) metal-semiconductor Schottky architecture, holding the dual feature of a hot-electron plasmonic system and a simple metal/semiconductor junction. We obtained a strongly enhanced external quantum efficiency (EQE) of the plasmonic Ag decorated ZnO semiconductor in both the band-edge region of ZnO and the corresponding plasmonic absorption profile of the Ag NPs (visible region). Simultaneously, the insertion of an insulating Al2O3 intermediate layer between Ag NPs and ZnO resulted in a parallel distinction of the two main non-radiative carrier transfer mechanisms of plasmonic NPs, i.e. direct electron transfer (DET) and plasmonic induced resonance energy transfer (PIRET). The multi-wavelength transient pump-probe spectroscopy indicated the very fast plasmonic radiative transfer dynamics of the system in <500 fs below 389 nm. We demonstrate a 13% increase of photogenerated current in ZnO upon visible irradiation as a result of non-radiative plasmonic hot-electron injection from Ag NPs. Overall, our device encompasses several effective solutions for designing a plasmonic system featuring non-radiative electron-electron plasmonic dephasing and high photoconversion efficiencies.
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| 9. |
- Gilzad Kohan, Mojtaba, et al.
(författare)
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Vertically aligned Co3O4 nanorods as a platform for inverted all‐oxide heterojunctions
- 2021
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Ingår i: Nano Select. - : John Wiley & Sons. - 2688-4011. ; 2:5, s. 967-978
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Tidskriftsartikel (refereegranskat)abstract
- Direct stacking of n‐type and p‐type metal oxide (MOx) semiconductors is one of the appealing directions toward low cost and environmentally friendly photovoltaics (PVs). However, the main shortcoming, hindering the PV performance of MOx heterojunction devices is attributed to the tradeoff between light absorption and maximized carrier extraction in p‐type MOx. In this work, we demonstrate that the nanorod (NR) geometry of Co3O4 light absorber with a nearly ideal bandgap of ∼1.48 eV, can remove this hurdle through strong internal light trapping of adjacent one‐dimensional (1D) structure and enhanced carrier mobility. The inverted n‐on‐p configuration of the core‐shell 1D heterojunction, obtained by depositing a thin TiO2 n‐type layer, resulted in enlarged charge generation compared to the typical p‐on‐n counterpart device. Fine‐tuning of Co3O4 NRs length, permits PV investigation of the heterojunctions with respect to absorber layers thickness. The optimized Co3O4 NRs/TiO2 heterojunction (30 nm Co3O4 NR length) presented a record high open circuit photovoltage (Voc) of (0.52 ± 0.03) V under 1 sun irradiation. Impedance analysis of the heterojunctions, indicates formation of the p+‐p depletion. The presented work can highlight some vital venues to enhance photoconversion efficiency of the all‐oxide heterojunctions while introducing a pioneer contender as inverted (n‐on‐p) MOx heterojunction.
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| 10. |
- Khasevani, Sepideh Gholizadeh, et al.
(författare)
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Empowering Adsorption and Photocatalytic Degradation of Ciprofloxacin on BiOI Composites: A Material-by-Design Investigation
- 2023
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:46, s. 44044-44056
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Tidskriftsartikel (refereegranskat)abstract
- Binary and ternary composites of BiOI with NH2-MIL-101(Fe) and a functionalized biochar were synthesized through an in situ approach, aimed at spurring the activity of the semiconductor as a photocatalyst for the removal of ciprofloxacin (CIP) from water. Experimental outcomes showed a drastic enhancement of the adsorption and the equilibrium (which increased from 39.31 mg g–1 of bare BiOI to 76.39 mg g–1 of the best ternary composite in 2 h time), while the kinetics of the process was not significantly changed. The photocatalytic performance was also significantly enhanced, and the complete removal of 10 ppm of CIP in 3 h reaction time was recorded under simulated solar light irradiation for the best catalyst of the investigated batch. Catalytic reactions supported by different materials obeyed different reaction orders, indicating the existence of different mechanisms. The use of scavengers for superoxide anion radicals, holes, and hydroxyl radicals showed that although all these species are involved in CIP photodegradation, the latter play the most crucial role, as also confirmed by carrying out the reaction at increasing pH conditions. A clear correlation between the reduction of BiOI crystallite sizes in the composites, as compared to the bare material, and the material performance as both adsorbers and photocatalyst was identified.
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