Enhanced activity of AgMgOTiO2 catalyst for photocatalytic conversion of CO2 and H2O into CH4
Enhanced activity of AgMgOTiO2 catalyst for photocatalytic conversion of CO2 and H2O into CH4
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DOI：
10.1016/j.ijhydene.2016.03.194
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发表时间：
2016-06
影响因子：
7.2
通讯作者：
Hai-long Li;Xianying Wu;Jun Wang;Yan Gao;Liqing Li;K. Shih
中科院分区：
文献类型：
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作者：
Hai-long Li;Xianying Wu;Jun Wang;Yan Gao;Liqing Li;K. Shih
利用太阳能回收二氧化碳（CO2）为同时缓解全球气候变化影响和生产含能化合物提供了全新的机会。通过浸渍和光沉积相结合的工艺合成银 (Ag) 和氧化镁 (MgO) 共改性二氧化钛 (TiO2) (AgMgTi)。通过表面积分析、X射线衍射（XRD）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、紫外-可见（UV-vis）漫反射光谱和光致发光光谱（PL）对催化剂进行了表征。 TEM 和 XPS 分析表明 AgMgTi 催化剂上存在 Ag 纳米颗粒 (NP)。 Ag NPs 和 MgO 的协同活性显着促进 CO2 光还原为甲烷 (CH4)。在紫外 (UV) 或紫外-可见光照射下，AgMgTi 催化剂的 CH4 产率比 P25 TiO2 高 20 倍，并且高于单一改性催化剂（MgO 单键 TiO2 或 Ag 单键 TiO2）。 TiO2 表面的 MgO 增强了 CO2 的化学吸附和/或引发了 CO2 还原过程，从而促进了 CO2 转化为 CH4。在紫外光激发下，沉积的银纳米颗粒由于在金属-半导体界面上形成肖特基势垒而促进了电子-空穴的分离。太阳光谱中的可见光通过增强银表面等离子共振（SPR）效应的局域电场，提高了银纳米粒子上捕获电子的能量。具有较高能量的丰富电子有利于CH4的形成。因此，与紫外光照射相比，在紫外可见光照射下获得了更多的CH4。这项研究表明，AgMgTi 催化剂可以有效地利用全光谱太阳能，同时还原二氧化碳和生产含能化合物。
Using solar energy to recycle carbon dioxide (CO2) offers a brand new opportunity for simultaneous mitigation of the global climate change effect and production of energy-bearing compounds. Silver (Ag) and magnesium oxide (MgO) co-modified titania (TiO2) (AgMgTi) synthesized through a combined impregnation and photo-deposition process. The catalysts were characterized through surface area analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy, and photoluminescence spectrum (PL). The TEM and XPS analysis demonstrated the presence of Ag nanoparticles (NPs) on the AgMgTi catalyst. The synergistic activities of Ag NPs and MgO significantly contributed to CO2photoreduction to methane (CH4). CH4yield over the AgMgTi catalyst was 20 times higher than over P25 TiO2, and was higher than over single modified catalysts (MgOsingle bondTiO2or Agsingle bondTiO2) under either ultraviolet (UV) or UV–vis irradiation. MgO on the surface of TiO2enhanced the chemisorption of CO2and/or initiated the CO2reduction process, and hence facilitated the conversion of CO2to CH4. Under UV light excitation, the deposited Ag NPs facilitated the separation of electron–hole due to the formation of Schottky barriers on the metal-semiconductor interface. Visible light in the solar spectrum improved the energy of trapped electrons on Ag NPs through enhanced localized electric field attributed to the Ag surface plasmon resonance (SPR) effect. Abundant electrons with higher energy facilitated CH4formation. Therefore, more CH4was obtained under UV–vis irradiation comparing to that under UV irradiation. This study demonstrated that the AgMgTi catalyst can effectively utilize full spectrum solar energy for simultaneous reduction of CO2and production of energy-bearing compounds.