Heterogenous Photocatalysis, Semiconductors, Physical Chemistry, Water treatment, Polllutant removal, SERS material
14
Scopus Publications
325
Scholar Citations
10
Scholar h-index
11
Scholar i10-index
Scopus Publications
Recyclable TiO2–Fe3O4 Magnetic Composites for the Photocatalytic Degradation of Paracetamol: Comparative Effect of Pure Anatase and Mixed-Phase P25 TiO2 Kata Saszet, Simona Guliman, Lilla Szalma, István Székely, Romulus Tetean, Milica Todea, Ákos Szamosvölgyi, Marieta Mureșan-Pop, Lucian Barbu-Tudoran, Klára Magyari, Lucian-Cristian Pop, Zsolt Pap, Lucian Baia Catalysts, 2025 Magnetically separable TiO2-based composite photocatalysts have gained significant interest in the past two decades; however, the optimization of their synthesis and the stabilization of the magnetic iron oxide within the composite is still an open challenge. The present study investigates the photocatalytic behavior and recyclability of TiO2-Fe3O4 composites, with emphasis on a possible correlation between pollutant degradation efficiency, recyclability, iron oxide stability, and the phase composition of the chosen TiO2 base. Magnetite nanoparticles were synthesized under varied temperature and alkaline conditions to identify optimal parameters for achieving the desirable magnetic properties. The magnetic nanoparticles were integrated into composite systems with either commercial TiO2 (Evonik Aeroxide P25 with anatase–rutile mixed phase) or a hydrothermally synthesized anatase TiO2. The P25-based composite removed 99% paracetamol from aqueous solutions under UV-A irradiation and demonstrated successful recyclability, maintaining 96% paracetamol degradation efficiency after four uses. In contrast, the anatase TiO2-based magnetic composite exhibited a lower performance (70%) and a significantly hindered recyclability (45% after four cycles). The difference in performance was attributed to variations in the phase composition of the employed TiO2 in the composites and, consequently, in their charge separation mechanisms.
Tungsten Oxide Morphology-Dependent Au/TiO2/WO3 Heterostructures with Applications in Heterogenous Photocatalysis and Surface-Enhanced Raman Spectroscopy István Székely, Zoltán Kovács, Mihai Rusu, Tamás Gyulavári, Milica Todea, Monica Focșan, Monica Baia, Zsolt Pap Catalysts, 2023 Developing highly efficient Au/TiO2/WO3 heterostructures with applications in heterogeneous photocatalysis (photocatalytic degradation) and surface-enhanced Raman spectroscopy (dye detection) is currently of paramount significance. Au/TiO2/WO3 heterostructures were obtained via heat or time-assisted synthesis routes developed by slightly modifying the Turkevich–Frens synthesis methods and were investigated by TEM, SEM, XRD, Raman spectroscopy, XPS, photoluminescence, and UV–vis DRS techniques. Structural features, such as WO3 crystalline phases, TiO2 surface defects, as well as the WO3 (220) to TiO2-A (101) ratio, were the key parameters needed to obtain heterostructures with enhanced photocatalytic activity for removing oxalic acid, phenol, methyl orange, and aspirin. Photodegradation efficiencies of 95.9 and 96.9% for oxalic acid; above 96% (except one composite) for phenol; 90.1 and 97.9% for methyl orange; and 81.6 and 82.1% for aspirin were obtained. By employing the SERS technique, the detection limit of crystal violet dye, depending on the heterostructure, was found to be between 10−7–10−8 M. The most promising composite was Au/TiO2/WO3-HW-TA it yielded conversion rates of 82.1, 95.9 and 96.8% for aspirin, oxalic acid, and phenol, respectively, and its detection limit for crystal violet was 10−8 M. Au/TiO2/WO3-NWH-HA achieved 90.1, 96.6 and 99.0% degradation efficiency for methyl orange, oxalic acid, and phenol, respectively, whereas its limit of detection was 10−7 M. The Au/TiO2/WO3 heterojunctions exhibited excellent stability as SERS substrates, yielding strong-intensity Raman signals of the pollutant molecules even after a long period of time.
Structural and flame retardancy properties of GO-DOPO-HAK composite Alin Grig Mihis, Liviu Cosmin Cotet, Calin Cadar, Lucian Cristian Pop, Milica Todea, Mihai Marius Rusu, Adriana Vulpoi, István Székely, Cătălin Alexandru Sălăgean, Klara Magyari, Marieta Muresan-Pop, Oana Cadar, Monica Baia, Ioana Emilia Sofran, Gabriela Lisa, Ion Anghel, Mihaela Baibarac, Virginia Danciu, Lucian Baia Journal of Materials Science, 2023
Rapid Synthesis Method of Ag3PO4 as Reusable Photocatalytically Active Semiconductor Zsejke-Réka Tóth, Diána Debreczeni, Tamás Gyulavári, István Székely, Milica Todea, Gábor Kovács, Monica Focșan, Klara Magyari, Lucian Baia, Zsolt Pap, Klara Hernadi Nanomaterials, 2023 The widespread use of Ag3PO4 is not surprising when considering its higher photostability compared to other silver-based materials. The present work deals with the facile precipitation method of silver phosphate. The effects of four different phosphate sources (H3PO4, NaH2PO4, Na2HPO4, Na3PO4·12 H2O) and two different initial concentrations (0.1 M and 0.2 M) were investigated. As the basicity of different phosphate sources influences the purity of Ag3PO4, different products were obtained. Using H3PO4 did not lead to the formation of Ag3PO4, while applying NaH2PO4 resulted in Ag3PO4 and a low amount of pyrophosphate. The morphological and structural properties of the obtained samples were studied by X-ray diffractometry, diffuse reflectance spectroscopy, scanning electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activity of the materials and the corresponding reaction kinetics were evaluated by the degradation of methyl orange (MO) under visible light. Their stability was investigated by reusability tests, photoluminescence measurements, and the recharacterization after degradation. The effect of as-deposited Ag nanoparticles was also highlighted on the photostability and the reusability of Ag3PO4. Although the deposited Ag nanoparticles suppressed the formation of holes and reduced the degradation of methyl orange, they did not reduce the performance of the photocatalyst.
Sensor surface via inspiration from Nature: The specific case of electron trapping in TiO2/WO3(∙0.33H2O) and reaction center/WO3(∙0.33H2O) systems Bíborka Boga, István Székely, Monica Focșan, Monica Baia, Tibor Szabó, László Nagy, Zsolt Pap Applied Surface Science, 2022 In this work, reaction center protein (RC) isolated from Rhodobacter sphaeroides purple bacteria was coupled with WO3(∙0.33H2O) via physical adsorption, where vectorial electron transfer (from RCs towards the inorganic carrier) was demonstrated using flash kinetics and photoluminescence measurements. The efficiency of the interaction between RCs and WO3(∙0.33H2O) was correlated to the components’ surface charge at the working pH and the structural/morphological and surface properties of the inorganic carrier (e.g., anchoring capacity assured by HO, WO bonds). The role of WO3(∙0.33H2O) as final electron trap and charge separator was proven not only in RCs/WO3(∙0.33H2O) biohybrid systems but also in TiO2/WO3(∙0.33H2O) composites. The charge transfer in the inorganic composites was evaluated by monitoring the reverse process of the color reaction (W5+ → W6+) via diffuse reflectance spectroscopy (DRS) after a previous UV-A (320–400 nm) exposure. The efficiency of the charge transfer process in inorganic systems was correlated to the initial W5+ content of WO3(∙0.33H2O), followed by the photocatalytic efficiency evaluation of these inorganic composites under UV-A irradiation.
Combination of iodine-deficient BiOI phases in the presence of CNT to enhance photocatalytic activity towards phenol decomposition under visible light Nikita Sharma, Zsolt Pap, István Székely, Monica Focsan, Gábor Karacs, Zoltan Nemeth, Seema Garg, Klara Hernadi Applied Surface Science, 2021 In this work, we have prepared BiOI/CNT composites by hydrothermal method and studied the impact of CNT and hydrothermal treatment conditions (temperature and time) simultaneously on phenomena such as crystallization. The samples were studied using X-ray Diffraction (XRD), nitrogen sorption (Brunauer–Emmett–Teller (BET) specific surface areas), Scanning Electron Microscopy assisted with Energy Dispersive X-Ray spectroscopy (SEM-EDX), High Resolution Transmission Electron Microscopy (HRTEM), UV–vis Diffuse Reflectance spectroscopy (DRS), Raman spectroscopy and photoluminescence spectroscopy (PL). The different heat treatments applied and varied amount of CNT was found to have a profound effect on the structural, morphological, compositional and optical properties of the prepared composites. The distinguishable changes in the above-mentioned properties were clearly visible for the samples prepared at higher temperature and longer duration (150 °C, 6.30 h). Surprisingly, the presence of other phases of BiOI, such as Bi7O9I3, Bi4O5I2, Bi5O7I, also co-existed at the same time, although in low amount. Finally, for the study, the photocatalytic efficiency of the prepared samples was tested for phenol and RhB, as model pollutants, under visible light irradiation for 240 min and 120 min, respectively. The results revealed that the composites prepared at higher temperature with longer duration showed superior performance for the photodegradation of phenol and RhB. Additionally, the composites performed better than their respective reference samples in each case. Interestingly, the introduction of CNT promoted the crystallinity in the composites and promising results for the removal of phenol and RhB were achieved by the use of low power ordinary visible lamps.
Synthesis design of electronegativity dependent wo3 and wo3∙0.33h2o materials for a better understanding of tio2/wo3 composites’ photocatalytic activity István Székely, Endre-Zsolt Kedves, Zsolt Pap, Monica Baia Catalysts, 2021 The design of a semiconductor or a composite semiconductor system—with applications in materials science—is complex because its morphology and structure depend on several parameters. These parameters are the precursor type, solvent, pH of the solution, synthesis approach, or shaping agents. This study gives meaningful insight regarding the synthesis design of such WO3 materials. By systematically alternating the precursor (sodium tungstate dihydrate—NWH, or ammonium tungstate hydrate—AMT), subsequently shaping the agents (halide salts—NaX, KX, or hydrohalic acids—HX; X = F−, Cl−, Br−, I−), we have obtained WO3 semiconductors by hydrothermal treatment, which in composite systems can enhance the commercial TiO2 photocatalytic activity. We investigated three sample series: WO3-NWH-NaX/WO3-NWH-KX and, subsequently, WO3-AMT-HX. The presence of W+5 centers was evidenced by Raman and X-ray photoelectron spectroscopy. W+5 and W+6 species affected the band gap values of the NaX and KX series; a higher percentage of W+5 and, subsequently, W+6 caused a redshift, while, regarding the HX series, it led to a blue shift. Increased electronegativity of the halide anions has an unfavorable effect on the composites’ photoactivity. In contrast, in the case of hydrohalic acids, it had a positive impact.
Preparation of TiO2/WO3 composite photocatalysts by the adjustment of the semiconductors' surface charge Lucian Baia, Eszter Orbán, Szilvia Fodor, Boglárka Hampel, Endre Zsolt Kedves, Kata Saszet, István Székely, Éva Karácsonyi, Balázs Réti, Péter Berki, Adriana Vulpoi, Klára Magyari, Alexandra Csavdári, Csaba Bolla, Veronica Coșoveanu, Klára Hernádi, Monica Baia, András Dombi, Virginia Danciu, Gábor Kovács, Zsolt Pap Materials Science in Semiconductor Processing, 2016
Recyclable TiO 2 –Fe 3 O 4 Magnetic Composites for the Photocatalytic Degradation of Paracetamol: Comparative Effect of Pure Anatase and Mixed-Phase P25 TiO 2 K Saszet, S Guliman, L Szalma, I Székely, R Tetean, M Todea, ... Catalysts 15 (9), 839 , 2025 2025 Citations: 5
α-MoO3 with inhibitive properties in Fenton reactions and insights on its general impact on OH radical based advanced oxidation processes EZ Kedves, C Fodor, A Fazekas, I Székely, Á Szamosvölgyi, A Sápi, ... Applied Surface Science 624, 156914 , 2023 2023 Citations: 10
Tungsten Oxide Morphology-Dependent Au/TiO 2 /WO 3 Heterostructures with Applications in Heterogenous Photocatalysis and Surface-Enhanced Raman … I Székely, Z Kovács, M Rusu, T Gyulavári, M Todea, M Focșan, M Baia, ... Catalysts 13 (6), 1015 , 2023 2023 Citations: 18
Experimental data-driven and phenomenological modeling approaches targeting the enhancement of CaTiO3 photocatalytic efficiency B Boga, VM Cristea, I Székely, F Lorenz, T Gyulavári, LC Pop, L Baia, ... Sustainable Chemistry and Pharmacy 33, 101045 , 2023 2023 Citations: 9
Structural and flame retardancy properties of GO-DOPO-HAK composite AG Mihis, LC Cotet, C Cadar, LC Pop, M Todea, MM Rusu, A Vulpoi, ... Journal of Materials Science 58 (16), 7025-7047 , 2023 2023 Citations: 4
Prediction of the Antioxidant Character by Using Photocatalytic Activity of Differently Shaped Cerium-oxide Nanoparticles ZR Tóth, K Magyari, A Feraru, I Székely, L Nánai, A Dreanca, L Baia Studia Universitatis Babes-Bolyai, Physica 68 , 2023 2023
Rapid Synthesis Method of Ag 3 PO 4 as Reusable Photocatalytically Active Semiconductor ZR Tóth, D Debreczeni, T Gyulavári, I Székely, M Todea, G Kovács, ... Nanomaterials 13 (1), 89 , 2022 2022 Citations: 18
How does the structure of pullulan alginate composites change in the biological environment? K Magyari, A Dreancă, I Székely, A Popescu, A Feraru, E Páll, T Gyulavári, ... Journal of Materials Science 57 (40), 19050-19067 , 2022 2022 Citations: 19
Sensor Surface via Inspiration from Nature: The Specific Case of Electron Trapping in TiO2/WO3(∙0.33H2O) and Reaction Center/WO3(∙0.33H2O) Systems B Boga, I Székely, M Focsan, M Baia, T Szabó, L Nagy, Z Pap Applied Surface Science 572, 151139 , 2022 2022 Citations: 3
Suspension Based on a Mixture of Titania-Silica-Functionalized Graphene Oxide for Surface Consolidation of Historical Andesite Stone and Mortar LC COTET, C SALAGEAN, A MIHIS, I SZÉKELY, ZS TOTH, L BAIA, ... Studia Universitatis Babes-Bolyai, Physica 67 , 2022 2022
Combination of iodine-deficient BiOI phases in the presence of CNT to enhance photocatalytic activity towards phenol decomposition under visible light N Sharma, Z Pap, I Székely, M Focsan, G Karacs, Z Nemeth, S Garg, ... Applied Surface Science 565, 150605 , 2021 2021 Citations: 41
Synthesis Design of Electronegativity Dependent WO 3 and WO 3 ∙0.33H 2 O Materials for a Better Understanding of TiO 2 /WO 3 Composites’ Photocatalytic Activity I Székely, EZ Kedves, Z Pap, M Baia Catalysts 11 (7), 779 , 2021 2021 Citations: 20
Mixture of graphene oxide/phosphoric acid/melamine as coating for improved fire protective performance and enhancement of surface electrical properties on wood chipboard LC Cotet, C Cadar, A Mihis, K Magyari, M Muresan-Pop, LC Pop, ... Journal of Nanoscience and Nanotechnology 21 (4), 2312-2322 , 2021 2021 Citations: 6
The effect of alkali and surfactant concentration, temperature and stirring on the cleaning efficiency of the carbon steel surface A Mihiş, V Danciu, CA Salagean, I Székely, MV Racolta-Paina, T S.C., ... Stud Univ Babeș-Bolyai Phys 66 (1-2), 79-90 , 2021 2021 Citations: 2
The effect of the pH adjustment upon the WO3-WO3·0.33H2O-TiO2 ternary composite systems' photocatalytic activity I Székely, M Baia, K Magyari, B Boga, Z Pap Applied Surface Science 490, 469-480 , 2019 2019 Citations: 29
The comparison of the photocatalytic performance shown by TiO2 and TiO2/WO3 composites—a parametric and kinetic study EZ Kedves, I Székely, L Baia, M Baia, A Csavdári, Z Pap Journal of Nanoscience and Nanotechnology 19 (1), 356-365 , 2019 2019 Citations: 13
Detailed Spectroscopic and Structural Analysis of TiO 2 /WO 3 Composite Semiconductors B Boga, I Székely, Z Pap, L Baia, M Baia Journal of Spectroscopy 2018 (1), 6260458 , 2018 2018 Citations: 29
Synthesis of Shape-Tailored WO 3 Micro-/Nanocrystals and the Photocatalytic Activity of WO 3 /TiO 2 Composites I Székely, G Kovács, L Baia, V Danciu, Z Pap Materials 9 (4), 258 , 2016 2016 Citations: 42
Preparation of TiO2/WO3 composite photocatalysts by the adjustment of the semiconductors' surface charge L Baia, E Orbán, S Fodor, B Hampel, EZ Kedves, I Székely, É Karácsonyi, ... Materials Science in Semiconductor Processing 42, 66-71 , 2016 2016 Citations: 57
MOST CITED SCHOLAR PUBLICATIONS
Preparation of TiO2/WO3 composite photocatalysts by the adjustment of the semiconductors' surface charge L Baia, E Orbán, S Fodor, B Hampel, EZ Kedves, I Székely, É Karácsonyi, ... Materials Science in Semiconductor Processing 42, 66-71 , 2016 2016 Citations: 57
Synthesis of Shape-Tailored WO 3 Micro-/Nanocrystals and the Photocatalytic Activity of WO 3 /TiO 2 Composites I Székely, G Kovács, L Baia, V Danciu, Z Pap Materials 9 (4), 258 , 2016 2016 Citations: 42
Combination of iodine-deficient BiOI phases in the presence of CNT to enhance photocatalytic activity towards phenol decomposition under visible light N Sharma, Z Pap, I Székely, M Focsan, G Karacs, Z Nemeth, S Garg, ... Applied Surface Science 565, 150605 , 2021 2021 Citations: 41
The effect of the pH adjustment upon the WO3-WO3·0.33H2O-TiO2 ternary composite systems' photocatalytic activity I Székely, M Baia, K Magyari, B Boga, Z Pap Applied Surface Science 490, 469-480 , 2019 2019 Citations: 29
Detailed Spectroscopic and Structural Analysis of TiO 2 /WO 3 Composite Semiconductors B Boga, I Székely, Z Pap, L Baia, M Baia Journal of Spectroscopy 2018 (1), 6260458 , 2018 2018 Citations: 29
Synthesis Design of Electronegativity Dependent WO 3 and WO 3 ∙0.33H 2 O Materials for a Better Understanding of TiO 2 /WO 3 Composites’ Photocatalytic Activity I Székely, EZ Kedves, Z Pap, M Baia Catalysts 11 (7), 779 , 2021 2021 Citations: 20
How does the structure of pullulan alginate composites change in the biological environment? K Magyari, A Dreancă, I Székely, A Popescu, A Feraru, E Páll, T Gyulavári, ... Journal of Materials Science 57 (40), 19050-19067 , 2022 2022 Citations: 19
Tungsten Oxide Morphology-Dependent Au/TiO 2 /WO 3 Heterostructures with Applications in Heterogenous Photocatalysis and Surface-Enhanced Raman … I Székely, Z Kovács, M Rusu, T Gyulavári, M Todea, M Focșan, M Baia, ... Catalysts 13 (6), 1015 , 2023 2023 Citations: 18
Rapid Synthesis Method of Ag 3 PO 4 as Reusable Photocatalytically Active Semiconductor ZR Tóth, D Debreczeni, T Gyulavári, I Székely, M Todea, G Kovács, ... Nanomaterials 13 (1), 89 , 2022 2022 Citations: 18
The comparison of the photocatalytic performance shown by TiO2 and TiO2/WO3 composites—a parametric and kinetic study EZ Kedves, I Székely, L Baia, M Baia, A Csavdári, Z Pap Journal of Nanoscience and Nanotechnology 19 (1), 356-365 , 2019 2019 Citations: 13
α-MoO3 with inhibitive properties in Fenton reactions and insights on its general impact on OH radical based advanced oxidation processes EZ Kedves, C Fodor, A Fazekas, I Székely, Á Szamosvölgyi, A Sápi, ... Applied Surface Science 624, 156914 , 2023 2023 Citations: 10
Experimental data-driven and phenomenological modeling approaches targeting the enhancement of CaTiO3 photocatalytic efficiency B Boga, VM Cristea, I Székely, F Lorenz, T Gyulavári, LC Pop, L Baia, ... Sustainable Chemistry and Pharmacy 33, 101045 , 2023 2023 Citations: 9
Mixture of graphene oxide/phosphoric acid/melamine as coating for improved fire protective performance and enhancement of surface electrical properties on wood chipboard LC Cotet, C Cadar, A Mihis, K Magyari, M Muresan-Pop, LC Pop, ... Journal of Nanoscience and Nanotechnology 21 (4), 2312-2322 , 2021 2021 Citations: 6
Recyclable TiO 2 –Fe 3 O 4 Magnetic Composites for the Photocatalytic Degradation of Paracetamol: Comparative Effect of Pure Anatase and Mixed-Phase P25 TiO 2 K Saszet, S Guliman, L Szalma, I Székely, R Tetean, M Todea, ... Catalysts 15 (9), 839 , 2025 2025 Citations: 5
Structural and flame retardancy properties of GO-DOPO-HAK composite AG Mihis, LC Cotet, C Cadar, LC Pop, M Todea, MM Rusu, A Vulpoi, ... Journal of Materials Science 58 (16), 7025-7047 , 2023 2023 Citations: 4
Sensor Surface via Inspiration from Nature: The Specific Case of Electron Trapping in TiO2/WO3(∙0.33H2O) and Reaction Center/WO3(∙0.33H2O) Systems B Boga, I Székely, M Focsan, M Baia, T Szabó, L Nagy, Z Pap Applied Surface Science 572, 151139 , 2022 2022 Citations: 3
The effect of alkali and surfactant concentration, temperature and stirring on the cleaning efficiency of the carbon steel surface A Mihiş, V Danciu, CA Salagean, I Székely, MV Racolta-Paina, T S.C., ... Stud Univ Babeș-Bolyai Phys 66 (1-2), 79-90 , 2021 2021 Citations: 2
Prediction of the Antioxidant Character by Using Photocatalytic Activity of Differently Shaped Cerium-oxide Nanoparticles ZR Tóth, K Magyari, A Feraru, I Székely, L Nánai, A Dreanca, L Baia Studia Universitatis Babes-Bolyai, Physica 68 , 2023 2023
Suspension Based on a Mixture of Titania-Silica-Functionalized Graphene Oxide for Surface Consolidation of Historical Andesite Stone and Mortar LC COTET, C SALAGEAN, A MIHIS, I SZÉKELY, ZS TOTH, L BAIA, ... Studia Universitatis Babes-Bolyai, Physica 67 , 2022 2022
