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首页> 外文期刊>Chemistry: A European journal >Investigation of electron behavior in nano-TiO_2 photocatalysis by using in situ open-circuit voltage and photoconductivity measurements
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Investigation of electron behavior in nano-TiO_2 photocatalysis by using in situ open-circuit voltage and photoconductivity measurements

机译：利用原位开路电压和光电导率测量研究纳米TiO_2光催化中的电子行为

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摘要

The in situ open-circuit voltages (V_(oc)) and the in situ photoconductivities have been measured to study electron behavior in photocatalysis and its effect on the photocatalytic oxidation of methanol. It was observed that electron injection to the conduction band (CB) of TiO _2 under light illumination during photocatalysis includes two sources: from the valence band (VB) of TiO_2 and from the methanol molecule. The electron injection from methanol to TiO_2 is slower than that directly from the VB, which indicates that the adsorption mode of methanol on the TiO_2 surface can change between dark and illuminated states. The electron injection from methanol to the CB of TiO_2 leads to the upshift of the Fermi level of electrons in TiO_2, which is the thermodynamic driving force of photocatalytic oxidation. It was also found that the charge state of nano-TiO_2 is continuously changing during photocatalysis as electrons are injected from methanol to TiO_2. Combined with the apparent Langmuir-Hinshelwood kinetic model, the relation between photocatalytic kinetics and electrons in the TiO_2 CB was developed and verified experimentally. The photocatalytic rate constant is the variation of the Fermi level with time, based on which a new method was developed to calculate the photocatalytic kinetic rate constant by monitoring the change of V_(oc) with time during photocatalysis.
机译：测量了原位开路电压（V_（oc））和原位光电导率，以研究光催化中的电子行为及其对甲醇光催化氧化的影响。观察到电子在光催化作用下在光照射下注入TiO _2的导带（CB）包括两个来源：来自TiO_2的价带（VB）和来自甲醇分子。从甲醇到TiO_2的电子注入比直接从VB注入的电子要慢，这表明甲醇在TiO_2表面上的吸附模式可以在黑暗和光照状态之间变化。从甲醇向TiO_2的CB中注入电子会导致TiO_2中电子的费米能级上移，这是光催化氧化的热力学驱动力。还发现随着电子从甲醇注入到TiO_2中，纳米TiO_2的电荷状态在光催化过程中不断变化。结合表观Langmuir-Hinshelwood动力学模型，开发并实验验证了TiO_2CB中光催化动力学与电子之间的关系。光催化速率常数是费米能级随时间的变化，以此为基础，开发了一种通过监测光催化过程中V_（oc）随时间的变化来计算光催化动力学速率常数的新方法。

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