Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan.
Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
Science. 2022 Oct 14;378(6616):202-206. doi: 10.1126/science.abq5868. Epub 2022 Oct 13.
A goal in the characterization of supported metal catalysts is to achieve particle-by-particle analysis of the charge state strongly correlated with the catalytic activity. Here, we demonstrate the direct identification of the charge state of individual platinum nanoparticles (NPs) supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. Sophisticated phase-shift analysis for the part of the NPs protruding into the vacuum visualized slight potential changes around individual platinum NPs. The analysis revealed the number (only one to six electrons) and sense (positive or negative) of the charge per platinum NP. The underlying mechanism of platinum charging is explained by the work function differences between platinum and titanium dioxide (depending on the orientation relationship and lattice distortion) and by first-principles calculations in terms of the charge transfer processes.
在负载金属催化剂的特性描述中，目标之一是实现与催化活性密切相关的单个颗粒的荷电状态的分析。在这里，我们通过超高灵敏度和高精度电子全息术，直接证明了负载在二氧化钛上的单个铂纳米颗粒（NPs）的荷电状态的直接识别。对突出到真空中的 NPs 部分进行复杂的相移分析，可视化了单个铂 NPs 周围的微小电位变化。该分析揭示了每个铂 NP 的电荷量（仅一个到六个电子）和电荷的正负（正或负）。通过比较铂和二氧化钛之间的功函数差异（取决于取向关系和晶格畸变），以及根据电荷转移过程的第一性原理计算，解释了铂充电的潜在机制。
