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Preparation of novel protonated forms of the ion-exchangeable layered perovskite via selective reaching of bismuth oxide sheets and their application to photocatalytic activities

通过选择性到达氧化铋片制备新型质子化形式的离子交换层状钙钛矿及其在光催化活性中的应用

基本信息

批准号：
14350462
负责人：
SUGAHARA Yoshiyuki
金额：
$ 9.73万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Photocatalytic activities of the protonated forms of ion-exchangeable layered perovskites.We investigated the photocatalytic activities of the Aurivillius phases Bi_2ANaNb_3O_<12> (A=Ca or Sr,Bi_2CaNaTa_3O_<12> and the protonated forms of ion-exchangeable layered perovskite prepared from these Aurivillius phases via selective leaching of bismuth oxide sheets by acid treatment. Photocatalytic activities were estimated based on H_2 evolution behavior from aqueous ethanol solutions (containing 20% ethanol) under UV irradiation. Aurivillius phases showed no activities for H_2 evolution, while the protonated forms exhibited the photocatalytic activities. UV-Vis diffuse reflectancee spectra indicated that selective leaching of bismuth oxide sheets led to the change in electric structure. XRD patterns of the protonated forms after H_2 evolution showed the increase in the interlayer distance, indicating the effective use of the interlayer space during H_2 evolution. Therefore, the difference i … More n the photocatalytic activity behavior between the Aurivillius phases and the protonated forms is attributable to the change in the position of the bottom of the conduction bands and/or the increases in surface area caused by the selective leaching of bismuth oxide sheets.Preparation of novel double-layered tungstic acid.We conducted acid treatment of an Aurivillius phase, Bi_2W_2O_9, whose structure was similar to that of ion-exchangeable layered perovskite. XRD,ICP and TG analyses as well as TEM observation showed the selective leaching of the bismuth oxide sheets, indicating the formation of the novel tungstic acid, H_2W_2O_7・nH_2O, which could potentially exhibit the photocatalytic activities.Reaction of the protonated forms of layered perovskite and alcohols.Since the n-alcohol is generally used as a sacrificial reagent for photocatalytic H_2 evolution from water, we investigated the interaction between the protonated forms of ion-exchangeable layered perovskite HCa_2Nb_2O_<10>・xH_2O and n-alcohol. The reaction of HCa_2Nb_2O_<10>・xH_2O with n-alcohols led to the formation of alkoxy-derivatives of HCa_2Nb_2O_<10>・xH_2O.To achieve high photocatalytic activities, we explored the new pillaring method using organic derivatives of layered perovskite. When we conducted the reaction of CH_2=CH(CH_2)_nO- derivatives (n=3,8) of HLaNb_2O_7・xH_2O with hydrochlorosilanes and oligosiloxanes, XRD,IR and NMR analyses showed the occurrence of hydrosilylation in the interlayer space, indicating that hydrosily lation is utilizable for pillaring. Less

研究了质子化形式的离子可交换型层状钙钛矿的光催化活性。我们研究了Aurivillius相Bi2ANaNb3O&lt；12&gt；(A=Ca或Sr，Bi2CaNaTa_3O_2&gt；12&gt；)的光催化活性，以及由这些Aurivillius相通过酸处理选择性地浸出氧化铋片而制备的质子化形式的离子交换型层状钙钛矿。根据乙醇水溶液(含20%乙醇)在紫外光照射下的析氢行为评价了其光催化活性。Aurivillius相不具有析氢活性，而质子化形式具有光催化活性。UV-Vis漫反射光谱表明，氧化铋片的选择性浸出导致了电子结构的变化。氢析出后质子化产物的X射线衍射谱表明，氢析出后质子化产物的层间距增大，说明氢析出过程中有效地利用了层间距。因此，不同的是I…Aurivillius相和质子化形式之间的光催化活性更多地归因于导带底部位置的改变和/或氧化铋片选择性浸出导致比表面积的增加。制备了新型双层钨酸。我们对结构类似于离子交换层状钙钛矿的Aurivillius相Bi2W2O9进行了酸处理。X射线衍射仪、电感耦合等离子体发射光谱、热重分析以及透射电子显微镜观察表明，氧化铋片被选择性地浸出，生成了可能具有光催化活性的新型钨酸H_2W_2O_7·nH_2O。层状钙钛矿的质子化形式与醇的反应。由于正醇通常被用作光催化从水中析出氢的牺牲剂，我们研究了质子化形式的层状钙钛矿HCa_2Nb_2O&lt；10&gt；·xH_2O与正醇之间的相互作用。HCa_2Nb_2O_10&gt；·xH_2O与正醇反应生成了烷氧基的HCa_2Nb_2O_10&gt；·xH_2O。为了获得较高的光催化活性，我们探索了层状钙钛矿有机衍生物的柱化方法。当HLaNb_2O_7·xH_2O的CH_2=CH(CH_2)_NO-衍生物(n=3，8)与氢氯硅烷和低聚硅氧烷反应时，X-射线衍射仪、红外光谱和核磁共振谱分析表明，氢硅化反应发生在层间空间，表明氢硅化反应是可行的。较少