• Energy Research

Abstract The two-step postsynthesis method (creation of vacant T-sites and associated SiOH groups by dealumination of BEA zeolite with nitric acid followed by incorporation of copper in the resulting SiBEA by impregnation with an aqueous solution of copper nitrate) allows to obtain a CuSiBEA zeolite which contains 0.8 Cu wt%. The incorporation of Cu(II) into the lattice of SiBEA is evidenced by XRD while the concomitant consumption of SiOH groups is monitored by FTIR. The presence of mainly isolated mononuclear Cu(II) in D 2d -distorted tetrahedral symmetry is evidenced by diffuse reflectance UV–vis-NIR, EXAFS and XANES. The CuSiBEA zeolite is active in the selective catalytic reduction (SCR) of NO with ethanol or propane with maximum NO conversion of 40 and 20% and selectivity toward N 2 close to 80–90 and 90–100%, respectively. These results suggest that the SCR process occurs on isolated mononuclear Cu(II) in D 2d -distorted tetrahedral symmetry after Al atoms have been removed from the zeolite structure. Thus, Cu(II) ions do not need Al atoms in their environment to be catalytically active. The lack of correlation between the SCR activity in presence of ethanol and the oxidation of NO to NO 2 suggests that the two reactions are more competitive than sequential. The higher activity of CuSiBEA with ethanol than with propane may be due to different activation energies and/or reaction mechanisms.

AbstractIn this paper we present a new composite (CuXX) of pastes for formation electrodes in crystalline silicon solar cells. The CuXX composite is obtained by chemical processing of copper particles and added to commercially available paste used for front electrode deposition on Si solar cell. The CuXX offers a possibility to exchange over 50wt. % Ag into Cu, which significantly decreases the material cost and therefore overall solar cell price. Solar cells with 50% wt. share of Cu as front electrode pastes were fabricated. The cells were characterized by current-voltage and spectral response techniques. Despite the non-optimized fabrication process, Cz-Si based solar cells with an efficiency approaching 14% were obtained.

The growing demand for sustainable energy solutions requires the development of safe and efficient systems for hydrogen utilization. Hydrogen, with its high energy density and clean combustion characteristics, has become a promising alternative for heating applications. However, conventional combustion technologies often suffer from inefficiencies and safety concerns, such as NOx emissions and explosion risks. To address these challenges, this study aimed to design and evaluate a catalytic heat generator utilizing hydrogen–air mixtures under controlled conditions to eliminate the need for pure oxygen and mitigate associated risks. A single-bed catalytic system was developed using palladium-based catalysts supported on ceramic fibers, followed by its heating, activation, and further characterization using the SEM-EDS technique. A multi-bed generator was later constructed to enhance scalability and performance. Thermal imaging and temperature monitoring were employed to optimize activation processes and assess system performance under varying hydrogen flow rates. The experimental results demonstrated efficient heat transfer and operational stability.

Abstract This paper shows an experimental attempt to approach plasmonic structure of silver nanoparticles (NPs) for photovoltaic application optimized previously for front side of thin film silicon solar cells. For that purpose the synthesis of high concentration of 100 and 140 nm Ag nanoparticles suspensions and layer-by-layer deposition method was applied. The results of electrical and optical studies of silicon solar cells with Ag nanoparticles as well as the microstructure of nanoparticles assemblies examined by SEM are presented. The results of these measurements are compared with theoretically predicted ones for optimized case and are the basis for further simulation analysis of the influence of the microstructure of actual nanoparticles assemblies. The simulations cover particles size distribution, the presence of agglomerates and arrangement. The results of these simulations show that the microstructure parameters decide on the plasmonic properties leading to the limited cell performance enhancement. Here we present more than 12% increase of short circuit current density and perspectives for further improvement. The outcomes of these studies have a general character and should be considered for optimization of other plasmonic structures used in photovoltaic and optoelectronic devices.

Thin films of tin (II) sulfide (SnS) were deposited onto a 500 µm thick copper substrate by a chemical bath method. The effect of sodium (Na) doping in these films was studied. The synthesis of the films was performed at temperatures of 60, 70, and 80 °C for 5 min. The microstructure of the SnS films analyzed by scanning electron microscopy (SEM) showed a compact morphology of the films deposited at 80 °C. The edges of the SnS grains were rounded off with the addition of a commercial surfactant. The thickness of different SnS layers deposited on the copper substrate was found to be 230 nm from spectroscopic ellipsometry and cross-section analysis using SEM. The deposition parameters such as temperature, surfactant addition, and sodium doping time did not affect the thickness of the layers. From the X-ray diffraction (XRD) analysis, the size of the SnS crystallites was found to be around 44 nm. Depending on the process conditions, Na doping affects the size of the crystallites in different ways. A study of the conductivity of SnS films provides a specific conductivity value of 0.3 S. The energy dispersive analysis of X-rays (EDAX) equipped with the SEM revealed the Sn:S stoichiometry of the film to be 1:1, which was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. The determined band-gap of SnS is equal to 1.27 eV and is in good agreement with the literature data.

Abstract The direct carbon fuel cells with solid oxide electrolyte (DC-SOFC) and anodes deposited by inject printing (EM/DCIJP) were studied. The cells were fed with carbon fuel obtained by the direct RF plasma splitting of methane. Since the (EM/DCIJP)M/DCIJP technology allows easy modification of electrode material, the effect of Cu addition to the Ni–YSZ anode was investigated. The significant improvement of the cell performance with the new anode was observed.

AbstractIn this article, we present the results of aging tests of silicon photovoltaic modules with a copper‐containing electrode deposited in one‐step screen printing method. For front metallization, a mixture of commercial silver paste with copper filler was used, where copper constituted 30% of total paste volume. The filler is based on copper particles about 1 μm of diameter covered with a protective coating layer based on nickel (CCu1) or nickel–silver (CCu2). For the first time, Si solar cells with screen‐printed front electrode containing massive copper with efficiency over 20% are reported. Aging tests included 2000 h of damp heat (DH) and 400 times of thermal cycling (TC) tests. TC results are very promising and provide slight deterioration of the electrical parameters of the modules with both CCu1 and CCu2. Greater decreases were found when performed DH tests, but it is worth pointing out that mainly fill factor (FF) and η have fallen while Voc and Isc did not change by more than 5% for both pastes. After 2000 h of the test, FF decreased by 28% for CCu1 and 37.4% for CCu2, whereas the efficiency deteriorated by 32% and 42.6% for CCu1 and CCu2. The electroluminescence (EL) and X‐ray photoelectron spectroscopy (XPS) measurements suggest that decrease in electrical parameters is a consequence of Cu corrosion caused by harmful products of the decomposed EVA laminating film.

Abstract The speciation of iron in FeSiBEA zeolites is investigated in order to evidence the “structure–properties” relationship in the selective catalytic reduction (SCR) of NO by ethanol. FexSiBEA zeolites are prepared in acidic (pH 2.5) (x = 0.3, 0.9 and 4.2 Fe wt%) or basic (pH 10) (x = 3.6 Fe wt%) conditions by a two-step postsynthesis method which allows to incorporate Fe into zeolite, as evidenced by XRD. For low Fe content (Fe0.3SiBEA, Fe0.9SiBEA), iron incorporated as Fe(III) ions generates Bronsted acidic sites as shown by FTIR of pyridine. Framework tetrahedral Fe(III) ions are evidenced by diffuse reflectance UV–vis, XANES and EXAFS. For higher Fe content (Fe4.2SiBEA), beside tetrahedral Fe(III) ions which are dominant, octahedral Fe(III) species are also present as shown by DR UV–vis, XPS and EXAFS. In contrast, for Fe3.6SiBEA prepared in basic condition (pH 10), an extra-framework Fe(III) oxide phase is mainly observed. The catalytic activity of FexSiBEA in the SCR of NO by ethanol strongly depends on the speciation of iron and a structure–properties relationship has been evidenced. Fe0.3SiBEA and Fe0.9SiBEA which mainly contain framework tetrahedral Fe(III) ions are active, with selectivity toward N2 exceeding 90% for NO conversion from 25% to 55%. When additional octahedral Fe(III) species are present (Fe4.2SiBEA), the full oxidation of ethanol and NO by O2 becomes important, with CO2 and NO2, respectively, appearing at the expenses of N2. The NO conversion linearly depends on Fe concentration assuming a first order reaction, suggesting that tetrahedral and octahedral Fe(III) species are well dispersed, as confirmed by XRD. The iron oxide phase is quite inactive, the activity and selectivity of Fe3.6SiBEA being governed by the small amount of tetrahedral Fe(III) ions.