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够高效地将可利用的太阳能转化为化学能的可见光敏感光催化剂。为了拓展等离子体纳米催化剂的研究，我们在不同形貌的二氧化钛载体上合成了不同形貌的金纳米粒子(NPs)，通过将锐钛矿型二氧化钛与不同的氢氧化钠、氢氧化钾和氢氧化锂在400K下水热处理30h，制备了不同形貌的纳米金纳米粒子(纳米管、纳米棒和微孔)，并利用其高比表面积和大孔容的特性对其进行光催化反应。从反应结果可以看出，在可见光照射下，金纳米粒子的等离子体激发对苯甲醇的有氧氧化有明显的促进作用，尤其是在以纳米管和纳米棒为载体的情况下。基于光谱分析，得出结论：Au纳米粒子的局域表面等离子体共振产生的电荷分离效应导致底物(电子供体)和O2(电子受体)在不同位置同时氧化和还原。尽管利用这种Au/TiO2光等离子体催化剂生产氢气和还原二氧化碳的扩展研究尚未完成，但我们预测这种利用太阳能设计的新型催化剂的进展肯定会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.