中文摘要：

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛，并在其悬浮体系中将CO2光催化还原合成甲醇．采用XRD，TEM，物理吸附，UV—Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究．结果表明：添加氧化硅后，氧化硅和二氧化钛之间形成Si—O—Ti键，抑制了TiO2晶粒生长，提高了锐钛型TiO2的比表面积，且随着含硅量的增加，SiO2／TiO2的UV吸收逐步蓝移，禁带宽度增加．还原反应结果表明：SiO2／TiO2具有光催化还原活性，且随着含硅量的增加先增加后减小，当SiO2质量分数为3．5％时，SiO2／TiO2复合催化剂反应活性最强，5h内甲醇产量可达到21．0mg／L，并有少量甲醛生成．

英文摘要：

Silica-modified anatase titanium dioxide was prepared by the hydrothermal method, with large surface area and high photocatalytic activity. Photocatalytic reduction of CO2 was carried out to synthesize methanol in the aqueous suspension system of nano TiO2. The catalyst was characterized by XRD, TEM, BET, UV-Vis diffuse reflectance and FTIR spectroscopy methods. The results showed formation of Si-- O---Ti bond on the silica-modified titanium dioxide surfaces. The addition of silica to TiO2 could restrain the growth of TiO2 crystalline grain and enhance the surface area. The silica-modified titanium dioxides had significant blue shift in UV absorption compared to the bulk TiO2. The reductive results of CO2 showed that the nano SiO2/TiO2 already obtained obvious photocatalytic reduction activity. When the addition of silica to TiO2 reached w（silica）=3.5%, it gave the highest activity, producing 21.0 mg/L of methanol during 5 h reaction under the irradiation of 365 nm UV light.