Abstract

Na₂Ti₆O₁₃ (NTO) and K₂Ti₆O₁₃ (KTO) catalysts were prepared by the sol–gel method by adjusting the pH during hydrolysis. Both the prepared catalysts exhibited a rod-like morphology, demonstrating some microstructural changes such as changes in their rod length, surface area, pore volume, and crystallinity as a result of the pH conditions during synthesis. It is assumed that these changes and the presence of impurities (TiO₂) were responsible for the different behaviors observed in the CO₂ photocatalytic reduction to formaldehyde and methanol under UV irradiation without any cocatalyst. For example, the NTO sample synthesized without catalyst (neutral media; N-NTO) showed the highest formaldehyde production (93 μmol g⁻¹), which may be due to the presence of TiO₂ in both the anatase and rutile phases (up to 10 w%). On the contrary, the neutral synthesized KTO sample (N-KTO), a purer catalyst than NTO (anatase concentration below 5 w%), enhanced methanol production (95 μmol g⁻¹) because of its more favorable physicochemical properties and band position.

中文翻译：

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通过不同pH催化的溶胶-凝胶合成的A 2 Ti 6 O 13（A = Na和K）钛酸酯上的光催化CO 2还原

摘要

Na ₂ Ti ₆ O ₁₃（NTO）和K ₂ Ti ₆ O ₁₃（KTO）催化剂是通过溶胶-凝胶法通过调节水解过程中的pH值制备的。两种制备的催化剂均显示出棒状形态，证明了一些微观结构变化，例如由于合成过程中的pH条件，其棒长，表面积，孔体积和结晶度的变化。假定这些变化和杂质（TiO ₂）的存在是造成CO _2中观察到的不同行为的原因。在没有任何助催化剂的情况下，在紫外线照射下光催化还原为甲醛和甲醇。例如，在没有催化剂的情况下合成的NTO样品（中性介质； N-NTO）显示出最高的甲醛生成量（93μmolg ^-1），这可能是由于锐钛矿相和金红石相中都存在TiO ₂（最高10 w％）。相反，中性合成的KTO样品（N-KTO）比NTO纯度更高（锐钛矿型催化剂浓度低于5 w％），由于其更有利的理化性质和能带位置，提高了甲醇的产量（95μmolg ^-1）。