Slightly hydrogenated TiO2 with enhanced photocatalytic performance
Slightly hydrogenated TiO2 with enhanced photocatalytic performance
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DOI：
10.1039/c4ta02192d
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发表时间：
2014-07
影响因子：
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通讯作者：
Yong Yan;Moyan Han;A. Konkin;Tristan Koppe;Dong Wang;T. Andreu;Ge Chen;U. Vetter;J. Morante
中科院分区：
文献类型：
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作者：
Yong Yan;Moyan Han;A. Konkin;Tristan Koppe;Dong Wang;T. Andreu;Ge Chen;U. Vetter;J. Morante
氢化TiO 2（H-TiO 2）由于其显著改善的太阳能吸收和优异的上级活性而引发了人们对纳米TiO 2的强烈研究兴趣。然而，导致H-TiO 2的光催化性能增强的主要因素仍然存在争议。为了澄清这个问题，H-TiO 2的结构特性，以及它们对光生电荷的影响，在这项研究中进行了全面的调查。采用H2等离子体处理法在几分钟内快速合成了不同氢化度的H-TiO 2纳米粒子，并分别以亚甲基蓝（MB）降解和CO2还原为目标，评价了其光催化活性。结果表明，与未还原的TiO 2（pristine-TiO 2）相比，具有原始白色的轻度氢化的TiO 2（s-H-TiO 2）纳米粒子表现出更高的光催化活性，尤其是对CO2的还原;而具有更高氢化度的灰色或黑色的H-TiO 2纳米粒子（h-H-TiO 2）表现出更差的催化性能。进一步的研究表明，s-H-TiO 2的高活性可能是由于表面缺陷的增加而导致的较高的空穴（O−中心）比率和较低的复合速率;相反，h-H-TiO 2纳米颗粒具有高浓度的体缺陷，导致O−中心的数量显著减少，非辐射复合增强，这强烈抑制了它们的光活性。这些结果可能为H-TiO 2的光催化活性提供新的见解，并为进一步研究其他氢化金属氧化物的光催化应用铺平了道路。
Hydrogenated TiO2 (H-TiO2) has triggered intense research interest in photocatalysis due to its substantially improved solar absorption and superior activity. However, the main factors that induce the enhanced photocatalytic performance of H-TiO2 are still under debate. In order to clarify this issue, the structural properties of H-TiO2, and their effects on photo-generated charges are comprehensively investigated in this study. H-TiO2 nanoparticles with different hydrogenation degrees are rapidly synthesized through H2 plasma treatment in several minutes; and their photocatalytic activities are evaluated by methylene blue (MB) degradation and CO2 reduction in aqueous and gaseous media, respectively. The slightly hydrogenated TiO2 (s-H-TiO2) nanoparticles with the original white color exhibit enhanced photoactivity compared with the pristine TiO2 (pristine-TiO2) nanoparticles especially for CO2 reduction; while the gray or black H-TiO2 nanoparticles with higher hydrogenation degrees (h-H-TiO2) display much worse catalytic performances. Further investigations reveal that the higher ratio of trapped holes (O− centers) and a lower recombination rate induced by the increase of surface defects might be the critical factors for the high activity of s-H-TiO2; in contrast, h-H-TiO2 nanoparticles possess high concentration of bulk defects, leading to a significantly decreased amount of O− centers and enhanced non-radiative recombination, which strongly inhibit their photoactivity. These results might provide new insights into the photoactivity of H-TiO2, and pave the way for further studies of other hydrogenated metal oxides for photocatalytic applications.