摘要/Abstract

为拓宽TiO₂的光吸收范围以及提高光生载流子的利用率，本工作利用B，N共掺杂改性的方法，通过聚合物前驱体法设计并制备了In₂O₃改性的TiO₂光催化剂.在前驱体合成中引入了聚乙二醇（PEG）作为致孔剂.PEG在前驱体转化为无机氧化物的热处理过程中分解离去、形成介孔等不同尺度的孔隙，提高了样品的比表面积.异质结结构在产物中得到有效构筑，带隙宽度由P25的3.09 eV缩窄至2.71 eV（样品IT-500，500℃退火产物）.B，N掺杂进入TiO₂晶格内，形成了Ti-N-B和Ti-O-B结构，同时也存在N的填隙掺杂，有助于带隙的缩窄、并拓宽可见光吸收范围.In₂O₃/TiO₂异质结结构的构筑，促进了电子-空穴对的分离与转移，提高了光生载流子的利用率.在大于380 nm可见光的照射下，样品IT-500的可见光催化产氢速率达到了5961 μmol·g^-1·h^-1，催化剂经过分离回收后进行循环实验，仍能保持良好的光催化活性.为了进一步提高其回收性，利用气纺丝制备了B，N掺杂的In₂O₃/TiO₂纳米纤维棉，在最佳焙烧温度500℃下，所获得的纤维棉状光催化剂的氢气产生速率达到1186 μmol·g^-1·h^-1，纤维棉简化了回收再利用的过程，经过5次循环实验后仍能达到初始产氢速率的97%.
关键词: 光催化, TiO₂, 非金属元素共掺杂, 异质结, 可见光响应, 纳米纤维
In order to improve light absorption range of TiO₂ and utilization rate of photogenerated carriers, we use B, N co-doping and In₂O₃ blending to modify the TiO₂ photocatalyst. Sample preparation is conducted through polymer precursor method and uniform distribution of the components is ensured. Polyethylene glycol (PEG) is added at the beginning of sample preparation and removed during the annealing process at high temperatures. X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission microscope (HRTEM), specific surface area and pore structure analyzer, X-ray photoelectron spectroscopy (XPS), ultraviolet-visible absorption spectrum and photoluminescence (PL) spectroscopy are used to characterize the products obtained. B and N elements have been detected in the lattice of TiO₂. Heterojunction structure of In₂O₃ and TiO₂ are also observed. Formation of Ti-N-B and Ti-O-B structure is exhibited in this system. Interstitial doping of N is also observed. These factors contribute to narrow the band gap from 3.09 eV of P25 to 2.71 eV of IT-500 (the modified sample annealed at 500℃). With the introduction and pyrolysis of porogen PEG, mesoporous structure is successfully constructed. Visible light absorption range has been greatly broadened in this modified TiO₂ based material. Utilization rate of photogenerated carriers has also been enhanced. When the catalyst is used in the photocatalytic hydrogen production experiment, under the irradiation of visible light (>380 nm), hydrogen production rate of IT-500 reaches 5961 μmol·g^-1·h^-1, which is far superior to commercial TiO₂ and most of the TiO₂ prepared by single modification method. The hydrogen production rate is maintained in the 5-circle test after the catalyst is separated and recycled. When the B, N-In₂O₃/TiO₂ polymer precursor is gas sprayed, which uses polyvinylpyrrolidone as spinning aid, ethanol and acetic acid as solvents, nanofiber sponge can be obtained and used for hydrogen production. Hydrogen production rate of this material reaches 1186 μmol·g^-1·h^-1 and keeps 97% after 5-cycle test, which shows high potential for commercial use of this material.
Key words: photocatalysis, TiO₂, Co-doping of non-metallic elements, heterojunction, visible-light response, nanofiber


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