Enhanced hydrogen production by hydrolysis of NaBH₄ using “Co-B nanoparticles supported on Carbon film” catalyst synthesized by pulsed laser deposition

• Published in: Catalysis today 2011-07, Vol.170 (1), p.20-26
• Main Authors: Patel, N, Fernandes, R, Bazzanella, N, Miotello, A
• Format: Article
• Language: English
• Subjects: activation energy; carbon; catalysts; catalytic activity; chemical reduction; cobalt; hydrogen; hydrogen production; hydrolysis; nanoparticles; powders; salts; sodium; surface area; temperature; transmission electron microscopy; X-ray diffraction
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2010.11.077

Co-B nanoparticles supported over carbon films were synthesized by using pulsed laser deposition (PLD) and used as catalysts in the hydrolysis of sodium borohydride (NaBH₄) to produce molecular hydrogen. Amorphous Co-B-based catalyst powders, produced by chemical reduction of cobalt salts, were used as target material for nanoparticles-assembled Co-B film catalysts preparation through PLD. Various Ar pressures (10–50Pa) were used during deposition of carbon films to obtain extremely irregular and porous-carbon support with high surface area prior to Co-B film deposition. Surface morphology of the catalyst films was studied using scanning and transmission electron microscopy, while structural characterizations were carried out using X-ray diffraction. The hydrogen generation rate attained by carbon-supported Co-B catalyst film is significantly higher as compared to unsupported Co-B film and to conventional Co-B powder. Morphological analysis along with NaBH₄ hydrolysis tests showed that the Co-B nanoparticles produced with PLD act as active catalytic centers for hydrolysis while the carbon support provides high initial surface area for the Co-B nanoparticles with better dispersion and tolerance against aggregation. The hydrogen generation rate obtained by the present catalyst film was also investigated as a function of Co-B loading, carbon morphology, and solution temperature. The high performance of our carbon-supported Co-B film is well supported by the obtained very low activation energy (∼31kJ (mol)⁻¹) and exceptionally high H₂ generation rate (8.1LH₂min⁻¹ (gofcatalyst)⁻¹) in the hydrolysis of NaBH₄.