【摘要】：半導(dǎo)體光催化材料用于光催化降解有機(jī)污染物和光解水制氫氣是當(dāng)前研究的熱點(diǎn)。與二氧化鈦(～3.1 eV)相比,鐵酸鉍材料具有較小的禁帶寬度(2.1-2.5eV),能夠有效的吸收見光,從而受到越來越多的人的關(guān)注。但是,合成單相的鐵酸鉍材料比較困難,因此,本論文主要研究單相鐵酸鉍的合成,探討不同制備工藝條件對合成鐵酸鉍的物相、形貌和可見光催化性能的影響,并分析提出了其光催化機(jī)理。主要結(jié)論如下：1.水熱合成：首次在反應(yīng)過程中加入分散劑PVP合成了分散性良好的立方形單相的鈣鈦礦結(jié)構(gòu)的鐵酸鉍(-2 um)。研究發(fā)現(xiàn)：PVP作為分散劑不僅改變合成的鐵酸鉍的分散度和形貌,還可以促進(jìn)合成的鐵酸鉍的結(jié)晶。研究這些不同尺寸和形狀的BiFe03樣品的光吸收和光催化性能可知：PVP作為分散劑合成的立方形的分散性良好的鐵酸鉍具有較好的可見光催化效果；對于顆粒尺寸相當(dāng)?shù)蔫F酸鉍而言,顆粒的形貌對鐵酸鉍光催化性能的影響比顆粒尺寸對光催化性能的影響更明顯。2.溶膠-凝膠合成：在較低的煅燒溫度(500℃)不加入任何螯合劑和分散劑的條件下,合成了～50 nm的單相的鐵酸鉍納米顆粒。研究發(fā)現(xiàn)：前驅(qū)體溶膠的濃度過低或過高都不利于合成單相的BiFeO3顆粒；在相同煅燒溫度下,前驅(qū)體溶膠的濃度越低合成的單相BiFe03顆粒的尺寸越�。粚τ诩{米尺寸的BiFeO3顆粒而言,尺寸越大光吸收性能越好,但是可見光催化性能卻越差。因此,比較光吸收性能和顆粒尺寸對光催化性能的影響,BiFeO3顆粒的尺寸是影響光催化性能的主要的因素。3.微波水熱合成：同樣實(shí)驗(yàn)條件下,微波水熱法合成單相鐵酸鉍的反應(yīng)時間遠(yuǎn)比水熱法快,并且合成的鐵酸鉍顆粒的分散性更好。研究不同反應(yīng)時間合成的鐵酸鉍發(fā)現(xiàn)：微波水熱反應(yīng)過程中BiFeO3和Bi25FeO40兩相會相互轉(zhuǎn)化；單相的鐵酸鉍的顆粒尺寸會隨著反應(yīng)時間的增加而增大。對于顆粒尺寸相當(dāng)?shù)蔫F酸鉍而言,鐵酸鉍的光吸收性能隨著顆粒增大而減小。
[Abstract]:Semiconductor photocatalytic materials used in photocatalytic degradation of organic pollutants and photolysis of water to produce hydrogen are the current research hotspot. Compared with titanium dioxide (~ 3.1 eV), bismuth ferrate material has a smaller band gap (2.1-2.5eV), which can effectively absorb light, which has attracted more and more attention. However, it is difficult to synthesize single phase bismuth ferrate material. Therefore, the synthesis of single phase bismuth ferrate is studied in this paper, and the effects of different preparation conditions on the phase, morphology and visible light catalytic performance of bismuth ferrate are discussed. The photocatalytic mechanism is also analyzed. The main conclusions are as follows: 1. Hydrothermal synthesis: bismuth ferrate (-2 um).) with good dispersion of square single phase perovskite structure was synthesized by adding dispersant PVP in the reaction process for the first time. It is found that PVP can not only change the dispersity and morphology of bismuth ferrate, but also promote the crystallization of bismuth ferrate. The photoabsorption and photocatalytic properties of these BiFe03 samples with different sizes and shapes were studied. The results showed that bismuth ferrate with good dispersion of square synthesized by PVP as dispersant had better visible light catalytic effect. For bismuth ferrate whose particle size is the same, the effect of particle morphology on the photocatalytic performance of bismuth ferrate is more obvious than that of particle size. 2. Sol-gel synthesis: single phase bismuth ferrate nanoparticles with ~ 50 nm were synthesized without any chelating agent and dispersant at lower calcination temperature (500 鈩，

本文編號：2293284