TY - JOUR

T1 - Amorphous ferromagnetic cobalt-boron composition reduced by sodium borohydride

T2 - Phase transformation at heat-treatment and its influence on the catalytic properties

AU - Netskina, O. V.

AU - Kellerman, D. G.

AU - Ishchenko, A. V.

AU - Komova, O. V.

AU - Simagina, V. I.

PY - 2018/1/20

Y1 - 2018/1/20

N2 - The cobalt-boron composition by reduction of cobalt chloride in an aqueous solution of sodium borohydride is an amorphous ferromagnetic black powder consisting of spherical particles covered with a shell. Transformations of cobalt-boron composition upon its heat treatment from 20 to 1000 °С in an inert atmosphere have been studied by thermal analysis, magnetic susceptibility and HR TEM. On the basis of the obtained results the heating process was divided into five temperature intervals characterized by considerable changes in the structure of cobalt-boron composition. The end products of chemical and structural transformations are cobalt metal and cobalt borates – Co2B2O5, Co3BO5, Co3(BO3)2. In our study it was shown for the first time that the metallic phase with a face-centered cubic lattice forms from the amorphous core while the cobalt borates form as a result of transformation of an oxygen-containing shell under an inert atmosphere. The study of the effect of physicochemical properties of the calcined cobalt-boron composition on the rate of NaBH4 hydrolysis has shown that it decreases with decline specific surface area of the sample and its phase composition determines the rate of formation of the catalytic active component in the reaction medium.

AB - The cobalt-boron composition by reduction of cobalt chloride in an aqueous solution of sodium borohydride is an amorphous ferromagnetic black powder consisting of spherical particles covered with a shell. Transformations of cobalt-boron composition upon its heat treatment from 20 to 1000 °С in an inert atmosphere have been studied by thermal analysis, magnetic susceptibility and HR TEM. On the basis of the obtained results the heating process was divided into five temperature intervals characterized by considerable changes in the structure of cobalt-boron composition. The end products of chemical and structural transformations are cobalt metal and cobalt borates – Co2B2O5, Co3BO5, Co3(BO3)2. In our study it was shown for the first time that the metallic phase with a face-centered cubic lattice forms from the amorphous core while the cobalt borates form as a result of transformation of an oxygen-containing shell under an inert atmosphere. The study of the effect of physicochemical properties of the calcined cobalt-boron composition on the rate of NaBH4 hydrolysis has shown that it decreases with decline specific surface area of the sample and its phase composition determines the rate of formation of the catalytic active component in the reaction medium.

KW - Amorphous material

KW - Catalysis

KW - Cobalt

KW - Phase transition

KW - Sodium borohydride

KW - Thermal analysis

KW - BORIDE CATALYSTS

KW - HYDROGEN GENERATION

KW - HYDROLYSIS

KW - NANOPARTICLES

KW - EFFICIENT CATALYST

KW - TEMPERATURE

KW - METAL

KW - ALLOY

KW - IN-SITU SYNTHESIS

KW - CO-B

UR - http://www.scopus.com/inward/record.url?scp=85032332563&partnerID=8YFLogxK

U2 - 10.1016/j.colsurfa.2017.10.052

DO - 10.1016/j.colsurfa.2017.10.052

M3 - Article

AN - SCOPUS:85032332563

VL - 537

SP - 485

EP - 494

JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects

JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects

SN - 0927-7757

ER -