等离激元催化反应动力学研究装置

An Apparatus for Investigating the Kinetics of Plasmonic Catalysis

等离激元催化是利用金属纳米颗粒的局域表面等离激元来驱动化学反应的现象,已经发展成为多相催化的一个新兴研究领域.然而,实验研究中温度测量不准和反应物吸附状态不明确导致等离激元催化反应的微观机制存在争议.为了研究等离激元催化反应动力学,本文设计搭建了一台基于在线质谱检测的装置,通过对反应器的改进来解决温度测量和吸附状态识别的问题.相比于传统设计中仅安装一个热偶,本文在反应器中安装了三个热偶.基于传热模型,这种多点测温技术可以定量计算出催化剂的有效温度以及热反应的贡献.此外,在装置中集成了程序升温脱附谱,用于测量反应物的吸附状态.通过对模型催化反应Au/TiO_(2)等离激元催化H_(2)+D_(2)→HD的定量测量,测试了该装置的性能,明确了H_(2)/D_(2)在Au/TiO_(2)界面的解离吸附和非热反应对HD生成的贡献,证明了该装置在等离激元催化反应动力学研究方面的能力.

Plasmonic catalysis,which is driven by the localized surface plasmon resonance of metal nanoparti-cles,has become an emerging field in heterogeneous catal-ysis.The microscop-ic mechanism of this kind of reaction,however,remains controversial partly because of the inaccuracy of tempera-ture measurement and the ambiguity of reagent adsorption state.In order to investigate the kinetics of plasmonic catalysis,an online mass spectrometer-based apparatus has been built in our laboratory,with emphases on dealing with temperature measurement and adsorption state identification issues.Given the temperature inhomogeneity in the catalyst bed,three thermocouples are installed compared with the conventional design with only one.Such a multiple-point temperature measuring technique enables the quantitative calculation of equivalent temperature and thermal reaction contribution of the catalysts.Temperature-pro-grammed desorption is incorporated into the apparatus,which helps to identify the adsorp-tion state of reagents.The capabilities of the improved apparatus have been demonstrated by studying the kinetics of a model plasmon-induced catalytic reaction,i.e.,H_(2)+D_(2)→HD over Au/TiO_(2).Dissociative adsorption of molecular hydrogen at Au/TiO_(2) interface and non-ther-mal contribution to HD production have been confirmed.