Enhanced hydrogen production by hydrolysis of NaBH 4 using “ Co-B nanoparticles supported on Carbon film” catalyst synthesized by pulsed laser deposition

Abstract

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 (NaBH 4) 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 (10–50 Pa) 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 NaBH 4 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 (∼31 kJ (mol) −1) and exceptionally high H 2 generation rate (8.1 L H 2 min −1 (g of catalyst) −1) in the hydrolysis of NaBH 4.