Novel 3-D printing of catalytic nanodiodes

催化纳米二极管的新型 3D 打印

• 批准号: 1356153
• 负责人: Eduardo Wolf
• 金额: $ 8万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1356153&HistoricalAwards=false
• 关键词: Novel; printing; catalytic; nanodiodes

Principal Investigator Eduardo Wolf of the University of Notre Dame has investigated the concept of the catalytic nanodiode with previous support from NSF and invested time and effort into developing the tools required to probe the intricacies of this device. The concept rests on the assumption that electron transfer effects will occur at catalyst metal-support interfaces in a similar way to those in a Schottky junction. Wolf hoped to control catalyst activity and selectivity by nanofabricating a device that will mimic this effect, and that will permit catalytic control by an external bias voltage in a similar way that electron flow is controlled in diodic rectifying junctions. Up until recently, the lack of proper nanofabrication tools prevented the realization at the nanoscale.PI Wolf made progress within the prior CBET award. The concept was buoyed with first principle simulations. The technique of Multilayer Enhanced Infrared Reflection Absorption Spectroscopy was developed by Wolf using polarized IR and varying the polarization and incidence angle to detect the orientation of CO molecules adsorbed on Pt nanowires. Next, electron transfer during CO adsorption on a Pt/TiO2 catalytic diode was demonstrated using the MEIRAS technique. Finally, the control of a reaction rate (CO adsorption) with an external bias voltage was demonstrated.This result demonstrates the hypothesis that control of the chemical bond can be achieved via an external voltage, a variable not studied before in the field of catalysis. Yet to be done is to control the selectivity of complex reactions. What is needed is more nanodiodes to study this new variable in catalysis. The main limitation of the catalytic diode as currently designed is that its 2D surface area is limited and the cost of nanofabrication of each device, which involves multiple steps that must be carried out separately in different equipment. Thus the current nanofabrication technique is certainly not competitive with the preparation of industrial catalysts.The Pt/TiO2/Au multilayer structure was prepared using optical lithography to create the bottom and top electrodes, and electron beam evaporation, followed by e-beam lithography . As a result the 5 nm Pt film deposited on the top of TiO2, although electrically continuous, had a rough surface at the atomic level, with cracks and a fraction of exposed Pt/TiO2 interfaces.PI Wolf will receive an EAGER award from the ENG Catalysis & Biocatalysis Program to carry out the high risk experimentation evaluating an improved methodology of fabricating catalytic diodes involving desktop nanofabrication with massively multiplexed beam pen lithography to fabricate a simple catalytic diode in a 3-D printer, but covering a 3? disk instead of the 4x4 mm area fabricated in the previous design. As to the best of Wolf?s knowledge, 3-D printing has not been attempted before in catalyst design. Thus, there is no guarantee that the proposed method of catalyst preparation will produce a catalyst with the characteristics of a catalytic diode. Nonetheless the knowledge acquired will create the foundation for future implementation of this work via 3-D printing which may have an important impact in the field of catalysis, sensors, and solar energy in the same way that 3-D printing is having transformative impact in manufacturing and medicine and biology.

圣母大学的首席研究员Eduardo Wolf在NSF的支持下研究了催化纳米二极管的概念，并投入时间和精力开发了探测该设备复杂性所需的工具。该概念基于这样的假设，即电子转移效应将以类似于肖特基结中的方式发生在催化剂金属-载体界面处。Wolf希望通过纳米制造一种模拟这种效应的装置来控制催化剂的活性和选择性，这种装置将允许通过外部偏置电压以类似于在二极管整流结中控制电子流的方式进行催化控制。直到最近，由于缺乏合适的纳米制造工具，在纳米尺度上的实现受到阻碍。PI Wolf在之前的CBET奖中取得了进展。这个概念是由第一原理模拟提出的。Wolf等人发展了多层增强红外反射吸收光谱技术，利用偏振红外光谱，通过改变偏振和入射角来检测吸附在Pt纳米线上的CO分子的取向。接下来，在CO吸附在Pt/TiO 2催化二极管上的电子转移证明使用MEIRAS技术。最后，通过外加偏压对反应速率（CO吸附）的控制，验证了通过外加电压可以控制化学键的假说，而外加电压是催化领域中以前没有研究过的变量。然而，要做的是控制复杂反应的选择性。需要更多的纳米二极管来研究催化中的这个新变量。目前设计的催化二极管的主要限制是其2D表面积有限，并且每个器件的纳米制造成本很高，这涉及必须在不同设备中单独进行的多个步骤。Pt/TiO 2/Au多层结构的制备采用光学光刻法来创建底部和顶部电极，并使用电子束蒸发，然后使用电子束光刻。结果，沉积在TiO 2顶部的5 nm Pt膜，尽管是电连续的，但在原子水平上具有粗糙的表面，具有裂纹和一部分暴露的Pt/TiO 2界面。PI Wolf将获得ENG催化生物催化计划的EAGER奖&，以进行高风险实验，评估制造催化二极管的改进方法，该方法涉及具有大规模多路复用的桌面纳米纤维。束笔光刻制造一个简单的催化二极管在3-D打印机，但覆盖3？盘，而不是在先前的设计中制造的4x 4 mm区域。最好的狼？据我们所知，3D打印在催化剂设计中还没有尝试过。因此，不能保证所提出的催化剂制备方法将产生具有催化二极管特性的催化剂。尽管如此，所获得的知识将为未来通过3D打印实施这项工作奠定基础，这可能会在催化，传感器和太阳能领域产生重要影响，就像3D打印在制造业，医学和生物学中产生变革性影响一样。