1. Single crystal synthesis and surface electronic structure of Bi_{1.993}Cr_{0.007}Se_{3}Sandra Gardonio, Zipporah Rini Benher, Mattia Fanetti, Paolo Moras, Polina M. Sheverdyaeva, Matjaž Valant, 2024, izvirni znanstveni članek Ključne besede: topological insulators, magnetic atoms, crystal synthesis, formation of clusters, surface electronic structure
Objavljeno v RUNG: 21.08.2024; Ogledov: 361; Prenosov: 3
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2. Understanding the in-situ transformation of ▫$Cu_xO$▫ interlayers to increase the water splitting efficiency in NiO/n-Si photoanodesChao Feng, Zhi Liu, Huanxin Ju, Andraž Mavrič, Matjaž Valant, Jie Fu, Beibei Zhang, Yanbo Li, 2024, izvirni znanstveni članek Opis: The buried interface tens of nanometers beneath the solid-liquid junction is crucial for photocarrier extraction, influencing the overall efficiency of photoelectrochemical devices. Precise characterization of the interfacial properties is essential for device optimization but remains challenging. Here, we directly probe the in situ transformation of a CuxO interlayer at the NiO/n-Si interface by hard X-ray photoelectron spectroscopy. It is found that Cu(I) in the CuxO interlayer gradually transforms to Cu(II) with air exposure, forming an energetically more favorable interface and improving photoanode’s efficiency. Based on this finding, a reactive e-beam evaporation process is developed for the direct deposition of a CuO interlayer, achieving a half-cell solar-to-hydrogen efficiency of 4.56% for the optimized NiO/CuO/n-Si heterojunction photoanode. Our results highlight the importance of precision characterization of interfacial properties with advanced hard X-ray photoelectron spectroscopy in guiding the design of efficient solar water-splitting devices.
Ključne besede: photo anode, energy harvesting, nickel oxide, interface
Objavljeno v RUNG: 01.08.2024; Ogledov: 554; Prenosov: 8
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3. Back to the future with emerging iron technologiesAndreea Oarga-Mulec, Uroš Luin, Matjaž Valant, 2024, pregledni znanstveni članek Opis: Here is a comprehensive overview of iron's potential in low-carbon energy technologies, exploring applications like metal fuel combustion, iron-based batteries, and energy-carrier cycles, as well as sustainable approaches for production and recycling with a focus on reducing environmental impact. Iron, with its abundance, safety, and electrochemical characteristics, is a promising material to contribute to a decarbonized future. This paper discusses the advancements and challenges in iron-based energy storage technologies and sustainable iron production methods. Various innovative approaches are explored as energy storage solutions based on iron, like advancements in thermochemical Fe–Cl cycles highlight the potential of iron chloride electrochemical cycles for long-term high-capacity energy storage technology. Additionally, the utilization of iron as a circular fuel in industrial processes demonstrates its potential in large-scale thermal energy generation. Sustainable iron production methods, such as electrolysis of iron chloride or oxide and deep eutectic solvent extraction, are investigated to reduce the carbon footprint in the iron and steel industry. These findings also show the importance of policy and technology improvements that are vital for the widespread use and recycling of iron-based tech, stressing the need for collaboration toward a sustainable future.
Ključne besede: iron's potential, low-carbon energy technologies
Objavljeno v RUNG: 02.07.2024; Ogledov: 559; Prenosov: 6
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4. Covalent-organic frameworks for luminescent sensorsTina Škorjanc, Matjaž Valant, 2024, samostojni znanstveni sestavek ali poglavje v monografski publikaciji Opis: In summary, this chapter discussed the richness of COFs that have been utilized in luminescence-based sensing of various analytes. Literature reports were classified based on the analyte type and a section was dedicated to each explosive compounds, metal cations, biological molecules, pH, VOCs, amines and water, anions, and enantiomers. Different design strategies implemented to develop sensors for each analyte were highlighted as were the detection mechanisms and key parameters of the performance, such as
LODs. In comparison to the state-of-the-art prior to 2020, we note several changes in the most recent developments of luminescent COF sensors.
Ključne besede: ensors, covalent organic frameworks, fluorescence, biosensor, explosives
Objavljeno v RUNG: 01.07.2024; Ogledov: 538; Prenosov: 2
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8. Designing atomic interface in ▫$Sb_2S_3/CdS$▫ heterojunction for efficient solar water splittingMinji Yang, Zeyu Fan, Jinyan Du, Chao Feng, Ronghua Li, Beibei Zhang, Nadiia Pastukhova, Matjaž Valant, Matjaž Finšgar, Andraž Mavrič, Yanbo Li, 2024, izvirni znanstveni članek Opis: In the emerging Sb2S3‐based solar energy conversion devices, a CdS buffer layer prepared by chemical bath deposition is commonly used to improve the separation of photogenerated electron‐hole pairs. However, the cation diffusion at the Sb2S3/CdS interface induces detrimental defects but is often overlooked. Designing a stable interface in the Sb2S3/CdS heterojunction is essential to achieve high solar energy conversion efficiency. As a proof of concept, this study reports that the modification of the Sb2S3/CdS heterojunction with an ultrathin Al2O3 interlayer effectively suppresses the interfacial defects by preventing the diffusion of Cd2+ cations into the Sb2S3 layer. As a result, a water‐splitting photocathode based on Ag:Sb2S3/Al2O3/CdS heterojunction achieves a significantly improved half‐cell solar‐to‐hydrogen efficiency of 2.78% in a neutral electrolyte, as compared to 1.66% for the control Ag:Sb2S3/CdS device. This work demonstrates the importance of designing atomic interfaces and may provide a guideline for the fabrication of high‐performance stibnite‐type semiconductor‐based solar energy conversion devices.
Ključne besede: alumina, defect passivation, interface engineering, photoelectrochemical water splitting
Objavljeno v RUNG: 11.03.2024; Ogledov: 1068; Prenosov: 3
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9. Chemistry of the iron-chlorine thermochemical cycle for hydrogen production utilizing industrial waste heatMatjaž Valant, Uroš Luin, 2024, izvirni znanstveni članek Opis: This research presents an inventive thermochemical cycle that utilizes a reaction between iron and HCl acid for hydrogen production. The reaction occurs spontaneously at room temperature, yielding hydrogen and a FeCl2 solution as a by-product. Exploring the thermal decomposition of the FeCl2 by-product revealed that, at conditions suitable for utilization of low-temperature industrial waste heat (250 °C), chlorine gas formation can be circumvented. Instead, the resulting by-product is HCl, which is readily soluble in water, facilitating direct reuse in subsequent cycles. The utilization of low-temperature industrial heat not only optimizes resource utilization and reduces operational costs but also aligns with environmentally sustainable production processes. From the kinetic studies the activation energy was calculated to be 45 kJ/mol and kinetics curves were constructed. They showed significant kinetics at room temperature and above but rapid decrease towards lower temperatures. This is important to consider during real-scale technology optimization. The theoretical overall energy efficiency of the cycle, with 100% and 70% heat recuperation, was calculated at 68.8% and 44.8%, respectively. In practical implementation, considering the efficiency of DRI iron reduction technology and free waste heat utilization, the cycle achieved a 41.7% efficiency. Beyond its energy storage capabilities, the Iron-chlorine cycle addresses safety concerns associated with large-scale hydrogen storage, eliminating self-discharge, reducing land usage, and employing cost-effective storage materials. This technology not only facilitates seasonal energy storage but also establishes solid-state energy reserves, making it suitable for balancing grid demands during winter months using excess renewable energy accumulated in the summer.
Ključne besede: chemical cycles, hydrogen production, thermal decomposition, reaction kinetics, iron, chlorine
Objavljeno v RUNG: 12.01.2024; Ogledov: 1397; Prenosov: 43
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10. The role of lattice defects on the optical properties of TiO[sub]2 nanotube arrays for synergistic water splittingManel Machreki, Takwa Chouki, Georgi Tyuliev, Mattia Fanetti, Matjaž Valant, Denis Arčon, Matej Pregelj, Saim Emin, 2023, izvirni znanstveni članek Opis: In this study, we report a facile one-step chemical method to synthesize reduced titanium dioxide (TiO2) nanotube arrays (NTAs) with point defects. Treatment with NaBH4 introduces oxygen vacancies (OVs) in the TiO2 lattice. Chemical analysis and optical studies indicate that the OV density can be significantly increased by changing reduction time treatment, leading to higher optical transmission of the TiO2 NTAs and retarded carrier recombination in the photoelectrochemical process. A cathodoluminescence (CL) study of reduced TiO2 (TiO2–x) NTAs revealed that OVs contribute significantly to the emission bands in the visible range. It was found that the TiO2 NTAs reduced for a longer duration exhibited a higher concentration of OVs. A typical CL spectrum of TiO2 was deconvoluted to four Gaussian components, assigned to F, F+, and Ti3+ centers.
Ključne besede: TiO2 nanotubes, defects, cathodoluminescence
Objavljeno v RUNG: 13.12.2023; Ogledov: 1004; Prenosov: 9
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