Controllable Synthesis Of Cobalt,Nickel Micro/Nanoparticles Assisted By Plant Phenolic Acid

Due to their unusual physical and chemical properties of the micro/nano metallic Co,Ni particles which have potential application value,these materials have attracted much attention in drug carrier,catalysis,information storage etc.During the recent years,the preparation of micro/nano Co,Ni particles has made great progress,however,there are still challenges in synthesis of the controllable size,morphology and composition of nanoparticles from the perspective of chemical preparation technology.Therefore,the study of novel green,controllable and efficient preparation of micro/nano Co,Ni particles is of great significance.In this paper,a green eco-friendly gallic acid(GA)had been used as crystal growth aid to synthesize a series of micro/nano Co,Ni particles with different structures and morphologies using hydrothermal and solvent-thermal by controlling reactant temperature and time,urea content,raw salt type and surfactant.The products were characterized by the combined techniques of XRD,FE-SEM,HR-TEM,TEM and VSM analysis.The main innovative results included:The ultrathin flake Co were synthesized by precipitation combined with hydrothermal method in which the reactants was using halide salt and sodium hydroxide as precursor.The results showed that two-dimensional flower-like Co particles were prepared by adding surfactant AOT,and the coercivity was significantly increased.The fluffy spherical Co particles were prepared by two-step hydrothermal method,and the precursors were synthesized using urea and halide salts.At the urea content of 0.0025 mol,and the hydrothermal temperature of 150℃ for 12 h was favorable to obtain fluffy spherical Co particles.Magnetic characterization of fluffy spherical Co particles coercivity was 46.94 Oe,suitable for making soft magnetic materials.The sea urchin-like Ni particles were prepared by hydrothermal plus solvent-thermal method using the reactants urea and metal salts as precursors.By adding GA,crystal structure of Ni particles changed from the mixed state of hexagonal phase and cubic phase to single cubic phase.The coercivity of sea urchin-like Ni particles prepared with a urea content of 0.0015 mol reached 255.14 Oe,which was much higher than that of block Ni.