Surface-plasmon-enhanced photocatalytic H2 generation and CO2 conversion over metal nanoparticles

本研究的主要目的是设计和开发能有效捕获和利用现有太阳能转化为化学能的可见光敏感光催化剂。为了进一步扩展等离子体纳米催化剂的研究，我们在不同形貌的TiO2载体材料上合成了金纳米粒子。采用NaOH、KOH和LiOH等碱水化物在400 K下水热处理30 h，制备了不同形态的TiO2（纳米管、纳米棒和微孔）。这些TiO2纳米管/纳米棒/微孔颗粒因其高表面积和大孔容而被用于容纳Au NPs进行光催化反应。从反应结果可以看出，在可见光照射下，Au纳米粒子的等离子体激发显著增强了苯甲醇的有氧氧化反应，特别是在TiO2纳米管和纳米棒作为载体材料的情况下。光谱分析表明，金纳米粒子的局部表面等离子体共振引起的电荷分离效应导致底物（电子供体）和O2（电子受体）在不同位置同时发生氧化和还原。虽然利用Au/TiO2等离子体催化剂生产H2和还原CO2的深入研究尚未完成，但我们预测，利用太阳能设计新型催化剂的这一进展必将促进清洁光催化系统的发展。

The main purpose of this research is to design and develop visible-light sensitive photocatalysts which can efficiently capture and utilize the available solar energy to chemical energy. To extend the research studies on plasmonic nanocatalysts, we synthesized Au nanoparticles (NPs) on different morphologies of TiO2 support material.Different morphologies of TiO2 (nanotube, nanorod and microporous) were prepared by the hydrothermal treatment of anatase TiO2 with different alkali hydroxides such as NaOH, KOH and LiOH at 400 K for 30 h. These TiO2 nanotube/nanorod/microporous particles were then used to accommodate Au NPs for carrying out the photocatalytic reaction because of its high surface area and large pore volume. It was observed from the reaction results that the aerobic oxidation of benzyl alcohol was significantly enhanced by the plasmonic excitation of Au NPs under visible light irradiation, especially in the case of TiO2 nanotube and nanorod as the support material. Based on spectroscopic analyses, it was concluded that the charge separation effect arising from the localized surface plasmon resonance of Au NPs caused a simultaneous oxidation and reduction of substrate (electron donor) and O2 (electron acceptor) at different sites.Although extended studies utilizing this Au/TiO2 plasmonic catalyst to H2 production and CO2 reduction have not been done yet, we predict that such progress in the design of new catalysts by utilizing solar energy will definitely foster the development of clean photocatalytic system.