Preparation Of Ni-based Amorphous Alloy And Evaluation Of Catalytic Activity For Hydrolysis Of NaBH₄Solution

As a new kind of nickel based amorphous alloy, NiB alloy possesses uniquephysicochemical properties and special applications owing to the long-range disorderwhile short-range order microstructure, in which the arrangement of Ni and B atomsin three dimensional space is isotropic and fairly similar to glassy state. The NiB alloyhas exhibited excellent catalytic performance, becoming a new kind of catalyticmaterials, which is especially useful for the catalytic hydrolysis of NaBH₄solution.As a part of the project supported by the Natural Science Foundation of China（No.21076063）, this work mainly focuses on the fabrication and characterization, aswell as the evaluation of catalytic activity, of the Ni-based catalysts with differentshapes and compositions. The main contents of the work are as follows:1. A series of NiB amorphous alloy powders have been prepared using threedifferent synthesizing methods, such as micro-emulsion method, complexing reductionmethod and surfactant assisted hydrothermal method.（1）. The multi-shaped NiB nano/micro powders were synthesized in severalmicroemulsion systems comprised of different content of cetyl-trimethyl-ammoniumbromide （CTAB）, n-amylalcohol and water. The results show that with the increase ofwater concentration, the morphologies of the obtained amorphous alloy NiB particleschange from sphere to dendritic shape, and average diameter of the NiB particlesreduces with the increase of n-amylalcohol content.（2）. NiB nano/micro powders with different sizes have been prepared bycomplexing-reduction method in the presence of such complexants as ammonia,salicylic acid and EDTA, which have in-turn increasing complexation ability. It isverified that the amorphous alloy NiB powders prepared by EDTA, possessing the best dispersity, has the strongest catalytic ability for the hydrolysis of NaBH₄.（3）. The NiB microspheres have been prepared with the help of three types ofsurfactants of CTAB、SDS and OP-10. The results show that the amorphous alloyNiB obtained under assistance of OP-10has the strongest catalytic ability for thehydrolysis of NaBH₄.2. A kind of bi-metallic catalysts, i.e. NiFeB, with different Fe/（Fe+Ni） molar ratios,were prepared by surfactant assisted reduction method.（1）. Different iron salts is selected as the Fe resource, through adjusting Fe/（Fe+Ni）molar ratios, and the NiFeB alloys with various phase compositions and morphologieshave been prepared and in detail investigated. The catalytic activity of as-preparedNiFeB powders has been comparatively studied for the hydrolysis of NaBH₄. It can befound that the hydrogen generation rate markedly increases with the molar content ofFe components, but excess amount of Fe may result in reduction of the rate ofhydrogen generation.（2）. The NiFeB catalyst powders have been prepared with the help of three differenttypes of surfactants, i.e. CTAB、SDS and OP-10. The results show that the amorphousalloy NiFeB powders prepared from nonionic surfactant （OP-10） have the strongestcatalytic ability for the hydrolysis of NaBH₄.3. Carbon nano-tube （CNTs）, active carbon （AC） and SiO2were employed assupports to fabricate supported oxide catalysts. The contrastive analysis shows that theamorphous alloy NiB supported on CNTs has the strongest catalytic ability for thehydrolysis of NaBH₄solution.4. The hydrolysis reaction rate of NaBH₄solution increases with the temperaturerising. The lesser impact caused by the NaBH₄concentration on hydrogen productionrate infers to the kinetic characteristics of zero-order reaction. Keeping the NaOHconcentration at5%in the solution could inhibit the hydrolysis of NaBH₄, but themaintenance of the NaOH concentration from10%to15%will significantly promotethe hydrolysis rate of NaBH₄solution.