| Abstract [eng] |
Research and development of hydrogen (H₂) energy technologies is one of the most promising areas of modern energy research and is being extensively investigated worldwide in response to growing energy and environmental challenges. Although hydrogen is considered one of the most promising clean energy carriers, the safe, efficient and controlled production and storage of hydrogen still remains important scientific and technological challenges. Therefore, this dissertation focuses on the development and investigation of advanced and efficient catalysts for the hydrolysis of NaBH4. The aim of this work was to develop nickel and NiM (M = Co, Mn, Mo, W) alloy coatings on a copper (Cu) surface, characterize their structural and catalytic properties, and evaluate their applicability for hydrogen generation from aqueous sodium borohydride solutions in an alkaline medium. To reduce the use of noble metals while simultaneously enhancing the catalytic activity of pure nickel, various binary, ternary, and quaternary nickel-based alloys containing cobalt (Co), manganese (Mn), molybdenum (Mo), and tungsten (W) were deposited onto a Cu substrate. Optimal coating formation conditions were determined to obtain highly active catalysts for hydrogen generation. The catalytic properties of the prepared coatings were evaluated based on the volume of hydrogen evolved during the NaBH4 hydrolysis reaction and the corresponding kinetic parameters. It was established that using the chemical deposition method and morpholine borane as a reducing agent, mono-, bi-, tri-, and quaternary nickel-based catalytic coatings were formed on the Cu surface. ICP–OES analysis demonstrated that varying the chemical deposition conditions enables the Ni, Co, Mo, and W contents of the coatings to be controlled over a wide concentration range, whereas the incorporation of Mn remains limited. The prepared coatings consisted of particles ranging from 0.1 to 3.5 μm in size, which formed agglomerates, and exhibited a compact and relatively uniform microstructure on the Cu surface. The highest catalytic activity toward the NaBH4 hydrolysis reaction was demonstrated by multicomponent coatings characterized by high hydrogen generation rates and relatively low activation energies. The most active catalysts were Ni70Co19Mo1W10/Cu (HGR – 13,00 mL/min, Ea – 38.22 kJ/mol) and Ni7.95Co84.71Mo7.33Mn0.01/Cu (HGR – 23.57 mL/min, Ea – 45.33 kJ/mol). Their enhanced catalytic activity is attributed to the synergistic interactions between the constituent metals. After five consecutive reuse cycles, the activity of the investigated catalysts remained above 85%, demonstrating that the chemically deposited coatings possess sufficient stability for the NaBH4 hydrolysis reaction. The most promising catalytic coatings developed in this work have potential for application as non-noble-metal catalysts in hydrogen generation systems. |
