Shedding Light on CO Oxidation Surface Chemistry on Single Pt Catalyst Nanoparticles Inside a Nanofluidic Model Pore,ACS Catalysis

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Shedding Light on CO Oxidation Surface Chemistry on Single Pt Catalyst Nanoparticles Inside a Nanofluidic Model Pore
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-02-01 , DOI: 10.1021/acscatal.0c04955
David Albinsson ₁ , Stephan Bartling ₁ , Sara Nilsson ₁ , Henrik Ström _{2,

3} , Joachim Fritzsche ₁ , Christoph Langhammer ₁

Affiliation

Investigating a catalyst under relevant application conditions is experimentally challenging and parameters like reaction conditions in terms of temperature, pressure, and reactant mixing ratios, as well as catalyst design, may significantly impact the obtained experimental results. For Pt catalysts widely used for the oxidation of carbon monoxide, there is keen debate on the oxidation state of the surface at high temperatures and at/above atmospheric pressure, as well as on the most active surface state under these conditions. Here, we employ a nanoreactor in combination with single-particle plasmonic nanospectroscopy to investigate individual Pt catalyst nanoparticles localized inside a nanofluidic model pore during carbon monoxide oxidation at 2 bar in the 450–550 K temperature range. As a main finding, we demonstrate that our single-particle measurements effectively resolve a kinetic phase transition during the reaction and that each individual particle has a unique response. Based on spatially resolved measurements, we furthermore observe how reactant concentration gradients formed due to conversion inside the model pore give rise to position-dependent kinetic phase transitions of the individual particles. Finally, employing extensive electrodynamics simulations, we unravel the surface chemistry of the individual Pt nanoparticles as a function of reactant composition and find strongly temperature-dependent Pt-oxide formation and oxygen spillover to the SiO₂ support as the main processes. These results therefore support the existence of a Pt surface oxide in the regime of high catalyst activity and demonstrate the possibility to use plasmonic nanospectroscopy in combination with nanofluidics as a tool for in situ studies of individual catalyst particles.

中文翻译：

揭示纳米流体模型孔内单 Pt 催化剂纳米粒子的 CO 氧化表面化学

研究相关应用条件下的催化剂在实验上具有挑战性，温度、压力和反应物混合比等反应条件以及催化剂设计等参数可能会显着影响所获得的实验结果。对于广泛用于一氧化碳氧化的铂催化剂，对于高温和大气压/高于大气压下的表面氧化态以及这些条件下最活跃的表面状态存在着激烈的争论。在这里，我们采用纳米反应器与单粒子等离子体纳米光谱相结合，研究在 450-550 K 温度范围内 2 bar 的一氧化碳氧化过程中位于纳米流体模型孔内的单个 Pt 催化剂纳米粒子。作为主要发现，我们证明我们的单粒子测量有效地解决了反应过程中的动力学相变，并且每个单独的粒子都有独特的响应。基于空间分辨测量，我们还观察了由于模型孔内的转换而形成的反应物浓度梯度如何引起单个颗粒的位置依赖性动力学相变。最后，通过广泛的电动力学模拟，我们揭示了单个 Pt 纳米粒子的表面化学与反应物成分的函数关系，并发现强烈依赖于温度的 Pt 氧化物形成和氧气溢出到 SiO ₂载体作为主要过程。因此，这些结果支持在高催化剂活性状态下存在 Pt 表面氧化物，并证明了使用等离子体纳米光谱与纳米流体相结合作为单个催化剂颗粒原位研究工具的可能性。

更新日期：2021-02-19

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