多种纳米结构Fe掺杂TiO2光热耦合水分解制氢研究

氧空位是材料缺陷工程的重要组成. 基于光生氧空位的直接热利用, 实现纯水分解制氢的光热耦合实验, 被认为是太阳能综合利用的有效途径. 以多种制备方法合成的TiO₂纳米材料为基础, 研究了多种形貌纳米TiO₂及其Fe掺杂改性材料的光热耦合反应能力. 通过高分辨透射电子显微镜(HRTEM)、 X射线衍射(XRD)和电子顺磁共振(EPR)对晶体特征进行表征, 利用漫反射光谱(DRS)、 光致发光(PL)和三电极测试法表征了材料的性能, 并结合密度泛函理论(DFT)计算了产氢反应路径. 研究结果表明, 溶胶-凝胶法制备的纳米颗粒相比水热法制备的纳米片及纳米线, 体相内缺陷较多, 载流子强度高, 光热耦合产氢效果较差. Fe掺杂改性扩展了光响应, 增强了载流子分离和寿命, 降低了电子传输阻抗, 利于光反应过程中光生氧空位的形成, 克服了制氢反应中的关键能垒. 同时, 纳米材料中的缺陷促进了Fe离子的有效掺杂, Fe掺杂TiO₂纳米颗粒的光热耦合平均产氢量为9.73 μmol/g, 性能提升达13倍.

Photo-thermal Coupling Water Splitting over Fe-doped TiO2 with Various Nanostructures

Oxygen vacancy（V_O） is an important part of the defect engineering. The direct thermal application of reductive photo-induced V_O has been regarded as an effective way for solar utilization in the field of hydrogen production from pure water splitting. Based on TiO₂ nanomaterials synthesized by various preparation me-thods， the performance of pure water splitting in photo-thermal coupling was tested on a variety of topography TiO₂ samples and its promoted form with Fe ions doping. The high resolution transmission electron microscopy（HRTEM）， X-ray diffraction（XRD） and electron paramagnetic resonance（EPR） were utilized for the observation of crystal characteristics. The diffuse reflectance spectroscopy（DRS）， photoluminescence（PL） and electrochemical characterization were applied to compare the materials properties. Moreover， the whole water splitting reaction pathway was performed via density functional theory（DFT）. Compared with hydrothermal nanosheets and nanowires， the nanoparticles prepared by sol-gel own abundant defects， resulting in a decline in hydrogen yield. To increase the photo-induced V_O generation during the photo reaction， which takes the highest energy barriers， the Fe doping was introduced into the nanomaterials， with the advantages of extended photoresponse， enhanced electron-hole pairs separation， prolonged carriers lifetime and decreased impe-dance. Meanwhile， defects in nanomaterials promote effective doping of Fe atoms， the average hydrogen yield on Fe-doped TiO₂ nanoparticles is 9.73 μmol/g in photo-thermal coupling reaction， which is almost 13 times to the bare TiO₂. The comparison and modification of nano TiO₂ with various morphologies provide a new approach for the solar functional materials.