Preparation And Catalytic Properties Of Ni-B Amorphous Alloy Nanoparticles

Direct methanol fuel cell(DMFC) has become a very attractive option because of the advantages of energy efficient and environmentally friendly in today’s urgent demand for clean energy. With the gradual depletion of natural resources, especially rare metals such as platinum, palladium and so on, how to develop efficient and affordable catalysts has been become the focus of this area.Amorphous materials have the special structures:short-range-disorder, long-range-order. Unsaturated sites with high concentrations of ligand leads to excellent catalytic activity, selectivity and easy reaction. Nano-materials has large specific surface area, high surface density and surface activity center. Amorphous combined with nano-material can cause higher electrochemical activity of capacity and stronger electro-chemically active, also can be used as effective means of improving the catalytic activity of the catalyst. In this paper, a series of amorphous Ni-B alloy nano-particles with different proportion of Ni/B atoms is synthesized by chemical reduction method. Using HRTEM, SAED, XRD, DSC, and XPS to do the characterizations. Using cyclic voltammetry to test electrochemical performance of amorphous alloy nanoparticles.Physical characterization of the results shows that:By XRD measurement, characteristics peak of Ni-B alloy Crystal metal were not found. By SAED and HRTEM to determine the alloys have amorphous long range disorder, short range ordered structure characteristic, and observed that the preparation of amorphous Ni-B alloy Nano particle is spherical or class, it’s average particle diameter is4-7nm, the aggregation is not evident. DSC test results showed that the earliest radiated peak of amorphous Ni-B alloy nano-particles appeared at342.8℃. With the increasing of proportion of B atoms in Ni-B alloy, the peak temperature of alloy radiated-peak first increased and then decreased, which Ni1B4start with the highest crystallization temperatures. That means its amorphous structure have better thermal stability than other catalysts and harder crystal into metallic Ni and B element. XPS analysis of the results shows that in the Ni-B amorphous alloy, B lost some electronics, and Ni got surplus electronic, Ni-B have electronic effects. Particle Ni atoms on the surface concentration first increased and then decreased with the increasing of B proportion. Among them, the Ni1B3had the minimal concentration. The atomic concentration of oxidation state nickel increased not clearly compared with the increasing of B percentage in alloy. Ni concentrations in the reactant increased and the Ni oxidation States concentration decreases, while the concentrations of Ni atoms increases.Cyclic voltammetry was studied for the first time in alkaline medium non-amorphous Ni-B alloy nano-particle on the electrocatalytic reaction of methanol. Results showed that the amorphous Ni-B alloy nano-particles on had a high activity in electrocatalytic oxidation of methanol. Based on the analysis of the curve of cyclic voltammetric of Ni-B amorphous alloy nanoparticles for in NaOH solution of different concentrations of methanol, found that the more concentrations of methanol, the larger peak of oxidation current density. With the increasing of B in alloy, its electrocatalytic oxidation of methanol by first weakening and then enhancement. Among them, Ni1B4had the weakest oxidizing ability.With the increasing of the Ni concentration as a reactant, the catalytic performance for methanol of the amorphous Ni1B2alloy nanoparticles increased as well. Through50scans of the catalyst, the peak current density in amorphous alloys declined26.8%percent. Comparison of crystalline Ni1B4and amorphous Ni1B4electro-catalytic oxidation of methanol showed that:Amorphous alloys have a lower starting voltage and Spike, but the peak oxidation current density is lower than crystalline alloys.