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分别采用Na Bi O3和Bi(NO3)3为Bi源制备了Bi掺杂Na Ta O3光催化剂,研究了Bi离子的价态对Na Ta O3光催化分解水制氢性能的影响.采用X射线衍射(XRD)、拉曼光谱、X射线光电子能谱(XPS)和紫外-可见吸收光谱研究了催化剂的晶体结构、Bi离子的化学状态和催化剂的光学吸收性能.以光催化分解水制氢反应研究了Bi离子掺杂Na Ta O3的催化性能.XRD结果表明,对于两个不同Bi源掺杂的Na Ta O3样品,Bi离子的掺杂没有改变催化剂的单斜相结构,但拉曼光谱证实Bi离子的掺杂致使Ta–O–Ta键角偏离了180o.XPS结果表明,以Bi(NO3)3为Bi源时,Bi离子以Bi3+掺杂于Na Ta O3的A位;当以Na Bi O3为原料时,Bi3+和Bi5+共掺杂于Na Ta O3的A位.两种不同Bi源掺杂得到的样品在紫外-可见吸收光谱中给出了相似的光学吸收,但Bi3+的掺杂对Na Ta O3光催化性能影响不大,而Bi3+和Bi5+共掺杂大大提高了Na Ta O3的光解水制氢性能.Bi离子取代Na离子在A位的掺杂,在Na Ta O3结构中引入了能够促进载流子分离的空位和缺陷;与此同时,Bi的掺杂导致Ta–O–Ta键角偏离180o而不利于载流子迁移.对于Bi3+掺杂的Na Ta O3样品,这两种作用相互抵消,使得其催化性能与Na Ta O3相比没有变化;而Bi3+和Bi5+的共掺杂和高价态Bi5+的掺杂引入了更多的空位和缺陷,提高了光生电子-空穴的分离效率,从而提高了光催化产氢性能.研究表明,光催化过程中载流子的迁移是影响催化性能的重要因素,而在ABO3钙钛矿结构的A位引入高价态离子是促进光生载流子分离的有效途径.
Bi-doped Na Ta O3 photocatalysts were prepared by using Na BiO3 and Bi (NO3) 3 as Bi sources, respectively. The effect of the valence of Bi ions on the photocatalytic decomposition of Na Ta O3 to produce hydrogen was investigated. XRD, (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectroscopy were used to study the crystal structure, the chemical state of Bi ions and the optical absorption of the catalyst. XRD results show that for two different Bi source doped Na Ta O3 samples, the doping of Bi ions did not change the monoclinic phase structure of the catalyst, but the Raman spectrum confirmed that Bi The doping angle of Ta-O-Ta was 180o.XPS results showed that when Bi (NO3) 3 was used as Bi source, the Bi ions were doped with Bi3 + in the A site of Na Ta O3. When Na BiO3 As raw materials, Bi3 + and Bi5 + were co-doped at the A site of Na Ta O3.The samples doped with two different Bi sources gave similar optical absorption in UV-Vis absorption spectra, but the doping of Bi3 + Ta O3 photocatalytic performance has little effect, and Bi3 + and Bi5 + co-doped Na Ta O3 greatly enhance the hydrogen production of photolysis water.Bi ions The substitution of Na ions at A site introduces vacancies and defects in Na Ta O3 structure that facilitate the carrier separation. Meanwhile, the doping of Bi causes the Ta-O-Ta bond angle to deviate from 180o, which is detrimental to Carrier mobility. For Bi3 + -doped Na Ta O3 samples, the two functions cancel each other out, so that their catalytic properties do not change compared with those of Na Ta O3. However, co-doping of Bi3 + and Bi5 + and doping of high-valence Bi5 + More vacancies and defects are introduced and the photo-electron-hole separation efficiency is improved, thereby improving the photocatalytic hydrogen evolution performance. The results show that the carrier mobility during photocatalysis is an important factor affecting the catalytic performance, and The introduction of high valent ions into the A site of the ABO3 perovskite structure is an effective way to promote the separation of photogenerated carriers.