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Enhanced photocatalytic inactivation of E.coli by natural pyrite in presence of citrate and EDTA as effective chelating agents: Experimental evaluation and kinetic and ANN models
摘要： The effect of chelating agents (citrate and EDTA) on the visible light photocatalytic activity of natural pyrite for the inactivation of Escherichia coli ATCC 25922 (E.coli) was investigated. The influence of various parameters, such as chelating agent and H2O2 concentration, light intensity and aeration rate, was evaluated experimentally and through kinetic models. The presence of a chelating agent enhanced the photocatalytic activity of natural pyrite, and citrate was more effective than EDTA, considerably improving bacteria inactivation in natural pH and reducing the drawbacks of the photocatalytic inactivation system. For both citrate-pyrite and EDTA-pyrite, the inactivation rate went through a maximum for a concentration of the chelating agent of 0.5 mM. The increase of the light intensity (10–60 mW cm-2), H2O2 concentration (10-25 mg L-1) and aeration rate (2-8 L min-1) improved the radical generation, resulting in a high inactivation effect. The low effect of H2O2 on the catalytic activity of pyrite in the presence of EDTA was likely due to the inhibition of the hydrogen peroxide-to-hydroxyl radical conversion by EDTA. On the other hand, degradation of citrate at high aeration rate occurred, decreasing the catalytic activity of the citrate-pyrite system. Scavenging tests indicated that the bulk hydroxyl radicals are the most reactive radical species in the bacterial inactivation, closely followed by valence band holes, while conduction band electrons play a less important role. In addition, in order to generate predictions and to better understand the process, artificial neural networks were used as models for the considered process: the obtained performance indexes indicated a good correlation between experimental and predicted values.
关键词： Pyrite,Photo-Fenton,E.coli,Photocatalytic inactivation,Chelating agents
更新于2025-09-23 15:22:29
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Pyrite thin films on amorphous substrates: Interaction with the substrate and doping effects
摘要： Recent published literature dealing with FeS2 pyrite (thin films and single crystals) faces a few and relevant issues: the low photovoltage presented by pyrite (mainly related to the singular nature of its surface), the not yet clearly defined way of making available n and p type reliable samples and the relevance of their stoichiometry. To address the second and third issues, Fe thin films, Ti/Fe and Co/Fe bilayers deposited on sodalime glass and amorphous quartz substrates have been sulfurated at different temperatures (Ts) (Ts ? 600°C) during 20 h to obtain pyrite thin films. Seebeck coefficient and Hall Effect measurements have been carried out at room temperature with the sulfurated samples. It has been found that sulfurated Ti/Fe on sodalime glass presents a change of the Seebeck coefficient sign (from negative to positive) due to a strong interaction of the Ti layer with the substrate, which is not present in the Ti/Fe samples deposited on amorphous quartz. As a consequence of the interaction, a new TiO2 layer is formed between the sodalime glass substrate and the pyrite layer. Sulfurated Co/Fe bilayers on sodalime glass show a coherent behavior according to the obtained results and previously published works. They all appear to be n-type semiconductors when Ts ? 175°C. Non-intentionally doped Fe thin films on sodalime glass behave in a non-conclusive fashion from the point of view of their electrical transport characterization. The Seebeck coefficient (S) of the sulfurated films appear to be S > 0 for all values of Ts. However, the value and sign of the Hall constant behave in a non-reproducible way. Results are discussed on the light of present knowledge of synthetic pyrite thin films growth and doping.
关键词： Thin films,Hall effect,Seebeck effect,Doping effects,Sodalime glass,Pyrite
更新于2025-09-19 17:15:36
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What Is Limiting Pyrite Solar Cell Performance?
摘要： Iron pyrite (FeS2), an earth-abundant transition metal di-chalcogenide (TMD), has exotic electronic and optical properties suitable for solar cell applications. For example, it has an indirect band gap at (cid:1)0.95 eV and a direct band gap at 1.05–1.10 eV that is comparable to Si (1.1 eV), while absorption coef?cient of FeS2 is almost two orders of magnitudes higher than that of Si. Like Si, FeS2 solar cells also could have almost same theoretical energy conversion ef?ciency up to Shockley-Queisser limit. Additionally, the high absorption coef?cient of FeS2 offers the opportunities to fabricate a very thin absorber layer of thickness < 20 nm, which so far does not seem possible with other thin-?lm solar cell materials. It infers a sharp reduction of the production cost (￠/W) of electricity due to reduction of material cost. Consequently, FeS2 has gained interest as a potential non-toxic super absorber material in lieu of widely used but toxic and rare element containing CdTe and Cu(In, Ga)Se2 for thin-?lm solar cells.
关键词： super absorber,band gap,FeS2,solar cell,non-toxic,Iron pyrite,thin-film,absorption coefficient,photovoltaic
更新于2025-09-19 17:13:59
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Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC <sub/>71</sub> BM-based organic photovoltaic cells
摘要： Herein, we report the synthesis of nontoxic pyrite iron sulfide (FeS2) nanocrystals (NCs) using a two-pot method. Moreover, we study the influence of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC71BM:FeS2/PFN/FM. The Field’s metal (FM) is a eutectic alloy composed of 32.5% Bi, 51% In and 16.5% Sn by weight that melts at 62 °C. It is deposited on the active layer/PFN under atmospheric conditions. Ternary active layers are prepared by adding small amounts of the semiconducting FeS2 NCs at different weight ratios of 0.0, 0.25, 0.5, and 1.0 wt % with respect to the electron donor PTB7. With respect to the reference device (without FeS2), a 21% increase in the power conversion efficiency (PCE) is observed for OPVs with 0.5 wt % FeS2, such that the PCE of the OPVs is enhanced from 5.69 to 6.47%. According to the Kruskal–Wallis and Mann–Whitney statistical tests, all OPV devices follow the same trend.
关键词： iron disulfide,nanoparticles,pyrite,organic photovoltaic cells (OPVs),PTB7
更新于2025-09-16 10:30:52
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Green and simple preparation of carbon-coated iron pyrite thin films for solar cells application
摘要： Carbon-coated iron pyrite (FeS2@C) was prepared by a green and simple method. The utilization of an amorphous carbon-shell layer formed from a glucose source coated on the surface of core-pyrite nanoparticles. The FeS2@C thin film was formed by coating synthesized iron pyrite nanoparticles with a carbon layer and depositing the carbon-coated iron pyrite on a fluorine-doped tin oxide (FTO) substrate by spin-coating. The morphological, structural, and chemical composition properties of FeS2@C film was measured and characterized. Devices with the structure of FTO/TiO2/redox electrolyte/counter electrodes (FeS2@C, pristine FeS2, and Pt)/FTO were fabricated. The power conversion efficiency (PCE) of the FeS2@C-device (PCE ~ 6.94%), the pristine FeS2-device (PCE ~ 5.69%), the Pt-device (PCE ~ 6.48%). The improving of the device performance indicated that the FeS2@C thin film can be a good counter electrode (CE) for the performance of dye-sensitized solar cells (DSSCs).
关键词： Dye-sensitized solar cells,Carbon-coated iron pyrite,FeS2@C,Counter electrode,Power conversion efficiency
更新于2025-09-11 14:15:04
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Theoretical Study of Ternary CoSP Semiconductor: A Candidate for Photovoltaic Applications
摘要： The electronic structure of pyrite-type cobalt phosphosulfide (CoSP) is studied using density-functional theory. The calculated band structure reveals the non-magnetic semiconducting character of the compound. The electronic structure is described using the electronic band structure and the densities of states. A band gap of 1.14 eV is computed within standard GGA, a value which is enhanced using hybrid functional. It separates the upper part of the valence band dominated by Co-3d-t2g states from the lower part of the conduction band made exclusively of Co-3d-eg, above of which lie S-3p and P-3p ones. The obtained values are suitable for applications in solar cells, according to Shockley–Queisser theory of light-to-electric conversion efficiency. The origin of the larger CoSP band gap, with respect to the one of the promising FeS2 compound, is explained and the chemical bonding properties are addressed. A comparative picture is established where several similarities are found, suggesting that CoSP could be of great practical interest in photovoltaics.
关键词： band gaps,pyrite disulfides,photovoltaics,chemical bondings,density-functional theory
更新于2025-09-11 14:15:04
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Na-mediated stoichiometry control of FeS <sub/>2</sub> thin films: suppression of nanoscale S-deficiency and improvement of photoresponse
摘要： Control of the constituent phase and stoichiometry of iron pyrite (FeS2) is a prerequisite for high-performance photovoltaic devices based on this material. If the pyrite contains sulfur-deficiency-related secondary phases, which have a metallic character and a high possibility of coexistence in pyrite films, significant carrier recombination is expected. In this work, the beneficial role of Na in suppressing the formation of nanoscale or amorphous sulfur-deficient secondary phases is reported with experimental evidence, leading to a higher phase purity for solution-processed pyrite films. The potential reduction of charge recombination via these metallic secondary phases results in significant improvements in both the photopotential and photocurrent intensity of Na-modified pyrite films compared with reference samples.
关键词： solar cell,sodium (Na),S deficiency,pyrite (FeS2),secondary phases
更新于2025-09-11 14:15:04
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Ultraviolet Irradiation on a Pyrite Surface Improves Triglycine Adsorption
摘要： We characterized the adsorption of triglycine molecules on a pyrite surface under several simulated environmental conditions by X-ray photoemission spectroscopy. The triglycine molecular adsorption on a pyrite surface under vacuum conditions (absence of oxygen) shows the presence of two different states for the amine functional group (NH2 and NH3+), therefore two chemical species (anionic and zwitterionic). On the other hand, molecular adsorption from a solution discriminates the NH2 as a unique molecular adsorption form, however, the amount adsorbed in this case is higher than under vacuum conditions. Furthermore, molecular adsorption on the mineral surface is even favored if the pyrite surface has been irradiated before the molecular adsorption occurs. Pyrite surface chemistry is highly sensitive to the chemical changes induced by UV irradiation, as XPS analysis shows the presence of Fe2O3 and Fe2SO4—like environments on the surface. Surface chemical changes induced by UV help to increase the probability of adsorption of molecular species and their subsequent concentration on the pyrite surface.
关键词： UV,XPS,triglycine,prebiotic chemistry,surface,adsorption,pyrite,peptide,sulfide mineral
更新于2025-09-10 09:29:36