Browsing by Author "Sahin, Omer"

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Citation - WoS: 3
Citation - Scopus: 3
Core-Shell Doping of Cerium Oxide With (Cr-Fe/Co)-b Catalyst for Enhanced Hydrogen Evolution in Borohydride Hydrolysis Systems: Performance and Catalytic Efficiency
(Springer, 2025) Sahin, Omer; Ceyhan, Ayhan Abdullah; Lakhali, Houssem
Herein, we successfully synthesized a CeO2@(Cr-Fe/Co)-B catalyst for hydrogen generation via NaBH4 and KBH4 hydrolysis using a hydrothermal method. To investigate the catalytic activity and hydrogen generation rate (HGR) of the catalyst, various parameters, including the catalyst amount, temperature, reusability, and the concentrations of MOH and MBH4 (M = Na, K), were tested. The catalyst was comprehensively characterized using FE-SEM, EDX, XRD, BET, TEM, XPS, and FTIR. The CeO2@(Cr-Fe/Co)-B catalyst exhibited a non-uniform, highly agglomerated, spherical morphology. TEM analysis revealed a core-shell structure with CeO2 as the core and an 8-16 nm (Cr-Fe/Co)-B shell. BET analysis confirmed the mesoporous nature of the catalyst, with a 27.19 nm pore diameter enabling efficient diffusion and interaction during reactions. The catalyst demonstrated excellent performance, achieving an HGR of 13.05 L g(metal)(-)(1) min(-)(1) for NaBH4 hydrolysis with an activation energy of 18.59 kJ mol(-)(1) and 9.06 L g(metal)(-)(1) min(-)(1) for KBH4 hydrolysis with an activation energy of 30.02 kJ mol(-)(1). Five consecutive experiments were conducted to evaluate the reusability of CeO2@(Cr-Fe/Co)-B for catalytic hydrolysis of NaBH4 and KBH4.
Citation - WoS: 2
Citation - Scopus: 2
Highly Efficient and Reusable CeVO4@Fe3O4/(Cr-Fe/Co) Magnetic Nanocatalyst for Sustainable Hydrogen Generation From NaBH4 Hydrolysis
(Elsevier Ltd, 2025) Sahin, Omer; Lakhali, Houssem; Ceyhan, Ayhan Abdullah
This study presents the hydrothermal synthesis of CeVO4@Fe3O4/(Cr-Fe/Co) and its catalytic performance in NaBH4 hydrolysis for hydrogen generation. Key parameters, including NaOH and NaBH4 concentrations, catalyst amount, and reaction temperature, were systematically optimized. Comprehensive characterization via SEM, EDX, XRD, BET, and FTIR revealed the structural and surface properties of the catalyst. The optimized catalyst exhibited an outstanding hydrogen generation rate of 19.65 L gmetal-1 min-1 at 30 degrees C with an activation energy of 34.43 kJ mol-1. FE-SEM analysis indicated particle agglomeration with a size distribution of approximately 60-70 nm, whereas the BET data demonstrated a moderate surface area and pore diameter of 46.34 m2 g-1 and 38.97 nm, respectively. Kinetic analysis using the Langmuir-Hinshelwood model revealed a moderate turnover frequency (TOF) of 2114.47 mol H2 mol cat-1 h-1. Thermodynamic parameters further supported the catalytic efficiency, with Delta S degrees = 0.0103 +/- 0.01 kJ mol-1 K-1, Delta Hads = 0.12 +/- 0.01 kJ mol-1, and Delta G degrees(30 degrees C) =-3.00 kJ mol-1. Remarkably, the catalyst maintained moderate efficiency after five reuse cycles, emphasizing its industrial viability and long-term stability. These findings suggest that CeVO4@Fe3O4/(Cr-Fe/Co) is a promising candidate for scalable hydrogen generation.
Citation - WoS: 5
Citation - Scopus: 5
A Novel Core-Shell Fe3O4@SiO2/Co-Cr-B Magnetic Catalyst for Efficient and Reusable Hydrogen Evolution From NaBH4 Hydrolysis
(Royal Soc Chemistry, 2025) Lakhali, Houssem; Sahin, Omer; Ceyhan, Ayhan Abdullah
This study presents a novel core-shell magnetic catalyst, Fe3O4@SiO2/Co-Cr-B, engineered for efficient and reusable hydrogen generation from NaBH4 hydrolysis, offering significant advancement in sustainable hydrogen production technologies. The innovation lies in the synergistic integration of a magnetic Fe3O4@SiO2 core with a bimetallic Co-Cr-B shell, which enhances catalytic activity, structural stability, and facile magnetic recovery. Field emission scanning electron microscopy (FE-SEM) revealed a distinctive grape-like morphology resulting from nanoparticle agglomeration, which increased the surface area and active site accessibility. Transmission electron microscopy (TEM) confirmed a well-defined core-shell architecture with a uniform Co-Cr-B shell thickness of 40-50 nm and a consistent particle distribution. These structural features directly contribute to the catalyst's high hydrogen generation rate of 22.2 L gmetal(-1) min(-1) at 30 degrees C with a turnover frequency (TOF) of 2110.61 mol(H2) molcat(-1) h(-1). The catalyst demonstrated remarkable stability and maintained >90% of its initial activity after six consecutive reusability tests. These findings highlight the potential of this catalyst for large-scale hydrogen production and offer a promising route for industrial applications with improved efficiency and durability.
Citation - WoS: 6
Citation - Scopus: 6
Novel Fe3O4@SiO2/Co-mo-b Core-Shell Magnetic Nanocatalyst: a Reusable System for High-Performance Hydrogen Evolution in Borohydride Hydrolysis
(Elsevier, 2025) Lakhali, Houssem; Ceyhan, Ayhan Abdullah; Sahin, Omer
The present study focuses on the synthesis of a Fe3O4@SiO2/Co-Mo-B core-shell nanocatalyst, designed as a high-performance and reusable system optimized for hydrogen evolution in borohydride hydrolysis reactions. The catalytic activity and hydrogen generation rate were evaluated by varying the catalyst amount, temperature, reusability, and MOH/MBH4 wt% (M = Na, K). A range of characterization techniques, including FE-SEM, EDX, XRD, BET, XRF, TEM, XPS, and FTIR, were used to analyze the structure and composition of the samples. The Fe3O4@SiO2/Co-Mo-B nanocatalyst demonstrated exceptional catalytic performance, achieving a hydrogen generation rate of 22.6 L gmetal -1 min-1 with an activation energy of 23.72 kJ mol-1 for KBH4 hydrolysis at 50 degrees C. For NaBH4 hydrolysis, the HGR was 27.5 L gmetal -1 min-1, with an activation energy of 32.18 kJ mol-1, demonstrating its high catalytic efficiency. Reusability studies over six successive cycles confirmed the stability of the catalyst, maintaining high hydrogen yields of 99.84 %-97.29 % for NaBH4 and 95.25 %-99.09 % for KBH4 across varying concentrations, further supporting its strong potential for industrial hydrogen storage and on-demand hydrogen generation. FE-SEM analysis revealed a grape-like morphology, while TEM confirmed a uniform CoMo-B coating (18-20 nm) on the SiO2 shell, forming a robust core-shell structure that enhanced stability and durability. Additionally, the successful silica coating of Fe3O4 and effective adsorption of Co-Mo-B were validated, both of which contributed to the sustained catalytic activity of the catalyst. The remarkable performance of Fe3O4@SiO2/Co-Mo-B in NaBH4 and KBH4 hydrolysis, combined with its low activation energy and high reusability, make it as a promising candidate for sustainable and scalable hydrogen generation.