Synthesis Of Nano-sized Mesoporous SiO₂ In Extremely Dilute Solution And Synthesis Of Non-layered Nano-sized Mesoporous Co₃O₄ With Novel Surfactants

Nano-sized mesoporous SiO₂ and the SiO₂ samples with Al doped are advantaged in structure character,such as high BET surface area,ordered pore channels,and controllable mesophases and structural parameters in the nanometer range.These mesoporous materials are widely appied to heterogeneous catalysis, biological fixation,adsorption separation and inorganic functional materials.Co₃O₄ material,an important P-type anti-ferromagnetic semiconductor material, can be applied to a wide range of electronic devices,sensors,magnetic heterostructures,catalyst and fuel Nano-sized Co₃O₄ nano-material shows a higher charge capacity in the charge/discharge cycle process when it was used as anode materials of lithium-ion secondary battery.Co₃O₄ is one of the transition metal oxides. Compared to silicon-based mesoporous materials,the precursor of Co₃O₄ intensively hydrolyze and polycondense,and the pore structure of the product is easy to collapse in calcinations process.Most of mesoporous Co₃O₄ is of layered structure through soft-template method and of small surface area,and small pore volume.All these make the application inconvenient.This paper focuses on the method of the synthesis of nano-sized SiO₂ and Al-doped SiO₂ at extremely low reactant concentration,and the method of nano-sized mesoporous Co₃O₄ through soft-template.First,Synthesis of nano-sized mesoporous silicon dioxide and that with Al doped were preformed at extremely low reactant concentration,and the products were controllable in size(20 nm～70 nm),morphology and pore structure by changing the amount of deionized water or Al source in the reaction.The samples were of higher BET surface area(more than 1000 m²/g) and pore volume(1.1～1.8 cm³/g).The pore structure became less ordered,the particle size decreased,the pore volume increased and a certain accumulation of holes appeared when decreasing reactants concentration or introducing Al source in the reaction.Second,to obtain non-layered structure of surfactant micelles and to achieve non-layered structure of Co₃O₄,We synthesized n-Octadecyl-N-iminodiacetic Acid (SHIDA) and n-Lauroyl-N-(dicarboxymethyl amino ethyl)-N-(carboxymethyl amino ethyl) amine(TCA).The parameter of sodium laurate,SHIDA and TCA decreased gradually.The samples of cobalt oxides were synthesized through the soft-templates of laurate.SHIDA and TCA,separately.The mesoporous Co₃O₄ particles which were synthesized with TCA template were of non-layered structure.These results were aggreed with the theory raised by Israelachvili:the parameter g plays a decisive role of mesostructure.At last,the "controlled calcined" Co₃O₄ sample was applied to the anode materials of lithium-ion secondary battery.The experiment shows the "controlled calcined" Co₃O₄ has enough low potential to be used as an anode material for Li ion batteries and much higher capacity.The cycling performance is not satisfactory and the experiment conditions need to be further optimized.