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Ce(IV)-centered charge-neutral perovskite layers topochemically derived from anionic [CeTa2O7]− layers
Chemical Science ( IF 7.6 ) Pub Date : 2021-10-15 , DOI: 10.1039/d1sc03053a Takuya Hasegawa 1 , Naoki Yamasaki 2 , Yusuke Asakura 1 , Tadaharu Ueda 2, 3 , Shu Yin 1
Chemical Science ( IF 7.6 ) Pub Date : 2021-10-15 , DOI: 10.1039/d1sc03053a Takuya Hasegawa 1 , Naoki Yamasaki 2 , Yusuke Asakura 1 , Tadaharu Ueda 2, 3 , Shu Yin 1
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Layered perovskites have been extensively investigated in many research fields, such as electronics, catalysis, optics, energy, and magnetics, because of the fascinating chemical properties that are generated by the specific structural features of perovskite frameworks. Furthermore, the interlayers of these structures can be chemically modified through ion exchange to form nanosheets. To further expand the modification of layered perovskites, we have demonstrated an advance in the new structural concept of layered perovskite “charge-neutral perovskite layers” by manipulating the perovskite layer itself. A charge-neutral perovskite layer in [CeIVTa2O7] was synthesized through a soft chemical oxidative reaction based on anionic [CeIIITa2O7]− layers. The Ce oxidation state for the charge-neutral [CeIVTa2O7] layers was found to be tetravalent by X-ray absorption fine structure (XAFS) analysis. The atomic arrangements were determined through scattering transmission electron microscopy and extended XAFS (EXAFS) analysis. The framework structure was simulated through density functional theory (DFT) calculations, the results of which were in good agreement with those of the EXAFS spectra quantitative analysis. The anionic [CeIIITa2O7]− layers exhibited optical absorption in the near infrared (NIR) region at approximately 1000 nm, whereas the level of NIR absorption decreased in the [CeIVTa2O7] charge-neutral layer due to the disappearance of the Ce 4f electrons. In addition, the chemical reactivity of the charge-neutral [CeIVTa2O7] layers was investigated by chemical reduction with ascorbic acid, resulting in the reduction of the [CeIVTa2O7] layers to form anionic [CeIIITa2O7]− layers. Furthermore, the anionic [CeIIITa2O7]− layers exhibited redox activity which the Ce in the perovskite unit can be electrochemically oxidized and reduced. The synthesis of the “charge-neutral” perovskite layer indicated that diverse features were generated by systematically tuning the electronic structure through the redox control of Ce; such diverse features have not been found in conventional layered perovskites. This study could demonstrate the potential for developing innovative, unique functional materials with perovskite structures.
中文翻译：
以 Ce(IV) 为中心的电荷中性钙钛矿层，拓扑化学源自阴离子 [CeTa2O7]− 层
由于钙钛矿框架的特定结构特征产生的令人着迷的化学性质，层状钙钛矿已在电子学、催化、光学、能源和磁学等许多研究领域得到广泛研究。此外，这些结构的夹层可以通过离子交换进行化学修饰，形成纳米片。为了进一步扩大层状钙钛矿的改性，我们通过操纵钙钛矿层本身，展示了层状钙钛矿“电荷中性钙钛矿层”新结构概念的进展。通过基于阴离子[Ce III Ta 2 O 7 ] -层的软化学氧化反应合成了[Ce IV Ta 2 O 7 ]中的电荷中性钙钛矿层。通过X射线吸收精细结构(XAFS)分析发现电中性[Ce IV Ta 2 O 7 ]层的Ce氧化态为四价。通过散射透射电子显微镜和扩展 XAFS (EXAFS) 分析确定原子排列。通过密度泛函理论（DFT）计算模拟了骨架结构，其结果与EXAFS光谱定量分析的结果吻合良好。 阴离子[Ce III Ta 2 O 7 ] -层在约1000 nm的近红外（NIR）区域表现出光学吸收，而[Ce IV Ta 2 O 7 ]电荷中性层的NIR吸收水平由于Ce 4f 电子消失。此外，通过抗坏血酸化学还原研究了电荷中性[Ce IV Ta 2 O 7 ]层的化学反应性，导致[Ce IV Ta 2 O 7 ]层还原形成阴离子[Ce III Ta 2 O 7 ] -层。此外，阴离子[Ce III Ta 2 O 7 ] -层表现出氧化还原活性，钙钛矿单元中的Ce可以被电化学氧化和还原。 “电荷中性”钙钛矿层的合成表明，通过对 Ce 的氧化还原控制系统地调整电子结构，可以产生多种特征；在传统的层状钙钛矿中尚未发现如此多样化的特征。 这项研究可以证明开发具有钙钛矿结构的创新、独特功能材料的潜力。
更新日期：2021-10-26
中文翻译：
以 Ce(IV) 为中心的电荷中性钙钛矿层，拓扑化学源自阴离子 [CeTa2O7]− 层
由于钙钛矿框架的特定结构特征产生的令人着迷的化学性质，层状钙钛矿已在电子学、催化、光学、能源和磁学等许多研究领域得到广泛研究。此外，这些结构的夹层可以通过离子交换进行化学修饰，形成纳米片。为了进一步扩大层状钙钛矿的改性，我们通过操纵钙钛矿层本身，展示了层状钙钛矿“电荷中性钙钛矿层”新结构概念的进展。通过基于阴离子[Ce III Ta 2 O 7 ] -层的软化学氧化反应合成了[Ce IV Ta 2 O 7 ]中的电荷中性钙钛矿层。通过X射线吸收精细结构(XAFS)分析发现电中性[Ce IV Ta 2 O 7 ]层的Ce氧化态为四价。通过散射透射电子显微镜和扩展 XAFS (EXAFS) 分析确定原子排列。通过密度泛函理论（DFT）计算模拟了骨架结构，其结果与EXAFS光谱定量分析的结果吻合良好。 阴离子[Ce III Ta 2 O 7 ] -层在约1000 nm的近红外（NIR）区域表现出光学吸收，而[Ce IV Ta 2 O 7 ]电荷中性层的NIR吸收水平由于Ce 4f 电子消失。此外，通过抗坏血酸化学还原研究了电荷中性[Ce IV Ta 2 O 7 ]层的化学反应性，导致[Ce IV Ta 2 O 7 ]层还原形成阴离子[Ce III Ta 2 O 7 ] -层。此外，阴离子[Ce III Ta 2 O 7 ] -层表现出氧化还原活性，钙钛矿单元中的Ce可以被电化学氧化和还原。 “电荷中性”钙钛矿层的合成表明，通过对 Ce 的氧化还原控制系统地调整电子结构，可以产生多种特征；在传统的层状钙钛矿中尚未发现如此多样化的特征。 这项研究可以证明开发具有钙钛矿结构的创新、独特功能材料的潜力。
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