Machida Masato, Yamasaki Nayu, Miyoshi Tomoya, Kusaba Hiroki, Sato Tetsuya, Awaya Keisuke, Yoshida Hiroshi, Ohyama Junya, Ohori Teppei, Oka Kohei, Fujii Kenji, Ishikawa Naoya
Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan.
Institute of Industrial Nanomaterials, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan.
Nanoscale. 2024 May 23;16(20):9781-9790. doi: 10.1039/d4nr01156b.
Pulsed cathodic arc-plasma deposition was employed to create a few nanometre-thick Pt overlayer on a 50 μm-thick Fe-Cr-Al metal (SUS) foil, resulting in an effective NH oxidation catalyst fabrication. This catalyst exhibited a turnover frequency (TOF) exceeding 100 times that of Pt nanoparticles. In this study, Pt overlayer catalysts with varying degrees of surface roughness were fabricated using different metal foil substrates: mirror-polished (Pt/p-SUS), unpolished (Pt/SUS) and roughened by the formation of a surface oxide layer (Pt/AlO/SUS). The nanoscale roughness was comprehensively analysed using electron microscopy, laser scanning confocal microscopy and chemisorption techniques. NH oxidation activity, measured at 200 °C, followed an increasing trend in the order of Pt/AlO/SUS < Pt/SUS < Pt/p-SUS, despite a decrease in the apparent Pt surface area in the same order. Consequently, the calculated TOF was markedly higher for Pt/p-SUS (267 min) compared to Pt/SUS (107 min) and Pt/AlO/SUS (≤22 min). The smooth Pt overlayer surface also favoured N yield over NO at this temperature. This discovery enhances our fundamental understanding of high-TOF NH oxidation over Pt overlayer catalysts, which holds significance for the advancement and industrial implementation of selective NH oxidation processes.
采用脉冲阴极电弧等离子体沉积法在50μm厚的铁铬铝金属（SUS）箔上制备了几纳米厚的铂覆盖层，从而制备出了一种有效的氨氧化催化剂。该催化剂的周转频率（TOF）超过了铂纳米颗粒的100倍。在本研究中，使用不同的金属箔基底制备了具有不同表面粗糙度的铂覆盖层催化剂：镜面抛光的（Pt/p-SUS）、未抛光的（Pt/SUS）以及通过形成表面氧化层而粗糙化的（Pt/AlO/SUS）。使用电子显微镜、激光扫描共聚焦显微镜和化学吸附技术对纳米级粗糙度进行了全面分析。在200℃下测得的氨氧化活性按照Pt/AlO/SUS＜Pt/SUS＜Pt/p-SUS的顺序呈上升趋势，尽管表观铂表面积以相同顺序减小。因此，与Pt/SUS（107分钟）和Pt/AlO/SUS（≤22分钟）相比，Pt/p-SUS的计算周转频率（267分钟）明显更高。在该温度下，光滑的铂覆盖层表面也有利于生成氮气而非一氧化氮。这一发现增进了我们对铂覆盖层催化剂上高周转频率氨氧化的基本理解，这对选择性氨氧化工艺的发展和工业应用具有重要意义。
