现阶段光催化CO₂还原研究中存在的主要科学问题之一是缺乏大量反应机理研究，还原产物的选择性难于调控[1, 2]。

光催化CO₂还原反应涉及多种反应路径和复杂的中间体[3]。因此，反应机理研究有助于对光催化CO₂还原复杂的反应动力学问题的深入理解，也有助于合理设计高活性和高选择性的光催化剂[4]。

光催化CO₂还原反应机理研究:原位表征技术

目前光催化CO₂还原反应机理研究主要通过原位表征技术确定反应中间体和催化活性中心[4]，主要涉及的原位表征技术主要包括原位电子顺磁共振（EPR）、原位漫反射紫外-可见光谱（UV-vis）和原位红外光谱（DRIFTS）[5-7]，其中原位红外光谱（DRIFTS）最为常见[8-13]。

原位红外漫反射反应池主要由三个窗口组成，其中两个窗口的材质为ZnSe或KBr，用于红外光的入射和反射；第三个窗口材质为SiO₂，用于光输入，结构如图1所示。

​图1. 原位红外漫反射反应池示意图

原位红外光谱测试中的光源选择

为了真实还原反应过程，原位红外光谱测试使用光源的光谱和光强尽量与活性评价所使用的光源一致，一般采用氙灯光源。

然而，氙灯光源的灯箱体积比较大，不易在狭小空间内移动，致使在进行原位红外测试时，空间受限严重。泊菲莱科技在Microsolar300氙灯光源的基础上新增PLS-300 光纤组件，可将光通过光纤改变方向后射入反应池体。输出光斑尺寸合适，出光口光斑直径5 mm；占用空间小，使用便捷。

石英光纤和液芯光纤两种选型，具体参数见表1.

​表1.光纤规格参数

具体使用场景示意图如图2所示。

​图2.氙灯光源结合PLS-300光纤组件与原位红外漫反射反应池使用场景示意图

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除此之外，为了满足高强度均匀光的实验需求，泊菲莱科技还开发设计了PLS-FX300HU高均匀性一体式氙灯光源，在光纤出口增加调焦镜筒，用于汇聚光线以提高输出光光功率密度，最大输出光功率密度≥700 mW/cm²。调焦镜筒亦可用于调节光斑大小，方形光斑尺寸10×10~50×50 mm²连续可调，使光斑完全覆盖催化剂工作区域，其输出光斑的均匀性高，可达A级太阳模拟器要求，是光电催化研究的专用氙灯光源。

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具体使用场景示意图及客户现场图如图3、图4。

​图3. 泊菲莱PLS-FX300HU高均匀性一体式氙灯光源与原位红外漫反射反应池使用场景示意图

​图4. 泊菲莱PLS-FX300HU高均匀性一体式氙灯光源与原位红外漫反射反应池客户现场图[14]

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