1. Colloidal metal nanoparticles as a source for the growth of thin filmsSaim Emin, 2022, published scientific conference contribution abstract (invited lecture) Abstract: Synthesis of colloidal nanoparticles (NPs) which offer good colloidal stability is quite important for different applications like spin-coating, dip-coating etc. Having metallic nanoparticles in the form of stable suspension allow the generation of thin films with desired thicknesses. We will present the production of different classes of materials starting from colloidal metal NPs. An example will be given on the preparation of Fe2O3 and WO3 thin films which are used in photoelectrochemical oxidation of water (e.g. water splitting). Another transformation which involves metallic NPs include the preparation of MoSe2 and WSe2 thin films which is achieved in a tube furnace at elevated temperatures. Very recently, the use of metallic NPs were also extended for the preparation of transition metal carbides. We managed to produce W2C and WC phases starting from metallic W NPs. The details of this phase conversion will be discussed. The presentation will provide details on how transition metallic NPs can be used to prepare metal oxide, metal selenide and metal carbides.
Keywords: colloidal metal nanoparticles, thin films, water splitting
Published in RUNG: 16.01.2025; Views: 903; Downloads: 0
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2. 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, original scientific article Abstract: 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.
Keywords: alumina, defect passivation, interface engineering, photoelectrochemical water splitting
Published in RUNG: 11.03.2024; Views: 2247; Downloads: 5
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4. Atomic layer deposition for the photoelectrochemical applicationsNadiia Pastukhova, Andraž Mavrič, Yanbo Li, 2021, review article Abstract: Substantial progress has been made in the photoelectrochemical (PEC) field to understand the photoelectrode behavior, semiconductor‐electrolyte interface, and photocorrosion, enabling new photoelectrode architectures with higher photocurrent, reduced photovoltage losses, and longer lifetime. Nevertheless, for practical PEC applications additional efforts are still needed to optimize all components of the photoelectrodes, including the light absorbing semiconductors, the layers for charge extraction, charge transfer, corrosion protection, and catalysis. In this regard, atomic layer deposition (ALD) offers new opportunities due to the monolayer‐by‐monolayer deposition approach, allowing preparation of conformal films with precisely controlled thickness and composition. As the ALD instruments are becoming widely accessible, this review aims to make an overview of the applications for photoelectrodes fabrication. The deposition of semiconductors onto flat and nano‐textured substrates, the deposition of ultrathin interlayers to ease charge transport by energy band alignment and surface states passivation, the deposition of corrosion protection layers, and finally, the possibilities for high catalyst dispersion is presented.
Keywords: atomic layer deposition, charge recombination, charge transfer, photocorrosion, photoelectrochemical water splitting
Published in RUNG: 25.02.2021; Views: 3695; Downloads: 142
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7. Synthesis of molybdenum carbide thin films for production of hydrogen via electrochemical water splitting : M. Sc. thesisCesur Altinkaya, 2018, master's thesis Keywords: molybdenum, platinum, molybdenum carbide thin films, hydrogen evolution reaction, water splitting, electrolysis, electrochemistry, pyrolysis, thin films
Published in RUNG: 30.08.2018; Views: 6617; Downloads: 0
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8. Photoelectrochemical Water Splitting Studies with nanostructured n and p-type semiconductor electrodesSaim Emin, Matjaž Valant, 2017, published scientific conference contribution abstract (invited lecture) Abstract: Photoelectrochemical water splitting has been demonstrated as a promising way to efficiently split water. Currently, solar-to-hydrogen conversion efficiency using state-of-the-art material combinations in PEC system is in the order of 7%. Fabrication of nanostructured materials with unique morphologies and compositions is an important factor to fully utilize the possibilities in this field. We will present different strategies for the preparation of nanostructured metal oxide thin films by using electrodeposition and wet-chemistry techniques. Focus will be given on the preparation of ZnO and CuO thin films where intermediate phases like Zn(OH)8Cl2.H2O and CuX (X=Br, Cl) were electrodeposited. Wet-chemistry synthesis techniques will be also explored for the preparation of nanostructured WO3 and a-Fe2O3 thin films. Especially, the hot-pyrolysis technique for the preparation of colloidal W and Fe/Fe-oxide nanoparticles will be shown. Spin-coating of W and Fe/Fe-oxide NPs onto optically conductive substrates and subsequent heat treatment of the obtained films was found to be a convenient way for the preparation of nanostructured WO3 and a-Fe2O3 thin films.
Keywords: photoelectrochemical water splitting, colloidal nanoparticles, semiconductor
Published in RUNG: 24.10.2017; Views: 5872; Downloads: 0
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9. Tungsten carbide thin films for electrochemical water splitting studiesSaim Emin, Cesur Altinkaya, Ali Semerci, Matjaž Valant, Hasan Okuyucu, Abdullah Yildiz, 2017, published scientific conference contribution abstract Abstract: We used wet-chemistry techniques to prepare colloidal tungsten (W) nanoparticles (NPs). The synthesis of W NPs was conducted using the so called hot-matrix method in 1-octadecene [1]. The sizes of obtained W NPs are in the order of 2 - 5 nm. These W NPs are coated with hydrophobic molecules which allow their dispersion in organic solvents like choloroform (CHCl3). It was found that the colloidal stability of the dispersions is exceptionally high exceeding several years. The stability of W NPs which prevents coagulation allows the preparation of thin films with uniform thicknesses by spin-coating, inkjet-printing and spray coating.
We have prepared tungsten carbide (W2C, WC) thin films. The preparation of W2C and WC was achieved by spin-coating of pre-synthesized W NPs on graphite substrate and following heat treatment under Ar atmosphere at 1000 and 1450°C.
The obtained W2C and WC films were used both in electrochemical water splitting studies. We also made a composite W2C-Pt films where we used only 5 at.% of Pt. The W2C-Pt composite has shown similar performance as pure Pt-C for hydrogen (H2) evolution. In conclusion, we have developed a procedure for the synthesis of W NPs which can be applied for the preparation of tungsten carbides films and their use for electrochemical water splitting.
Keywords: water splitting, nanoparticles, hot-matrix
Published in RUNG: 09.10.2017; Views: 8431; Downloads: 0
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