Stoichiometry, hierarchical arrangement and kinetics of electrode reactions at novel multi-components electrocatalytic materials

化石燃料储备的枯竭和严重的环境问题造成了巨大的能源挑战。现在不可否认的是，电化学--化学和电能的交换--即将在能源生产中发挥重要作用。作为一种清洁、可持续的能源技术，直接乙醇燃料电池(DEFC)已成为极具前景的车用低碳能源和便携式电子设备中可充电电池的替代品。然而，DEFC的低阳极催化剂活性和部分氧化副产物的产生阻碍了其商业化。此外，质子交换膜-DEFC被认为过于庞大和昂贵，而且它们可能会被高浓度的乙醇破坏，即所谓的乙醇交叉效应。我们的长期目标是开发效率高于60%的无膜混合反应物DEFCs(新技术)。在接下来的五年里，我们工作的主要目标是开发并获得新型纳米结构高效多组分阳极催化剂的合成-结构-催化活性关系(主题I)。努力的重点将是在铂金中添加助催化剂。我们将选择由储量丰富、价格低廉的金属氧化物材料结合超低含量的铂和铑组成的材料。我们希望发现最终活性催化剂表面和本体中三个组分的原子的最佳结构排列，以最大限度地提高活性和选择性。我们还将开发选择性阴极催化剂，该催化剂对氧还原反应具有电活性，同时可以耐受高浓度的乙醇(主题II)。考虑到氧分子的尺寸比乙醇小得多，我们的想法是开发一个表层材料层，氧气分子可以很容易地扩散并在层下的铂上被还原，而乙醇分子在表层表面保持阻挡。如此一来，可以使用更高的乙醇浓度，从而获得更好的电化学性能。这项提议的结果将涉及加拿大在开发基于先进纳米材料的电化学清洁/绿色技术方面的研究重点，以应对日益严峻的能源和环境挑战以及气候变化，同时培训高素质人员以利用这些机会。至于基本问题，这些研究将有助于建立界面结构、组成和对新型催化材料的力学方面的理解之间的确切关联。此外，这项拟议的研究计划将对加拿大的商业应用，如消费者的便携式电子产品和交通工具，或用于乙醇检测的基于道路安全燃料电池的传感器的特定用户具有重要意义。

The depletion of fossil fuel reserves and serious environmental issues has created tremendous energy challenges. It is now undeniable that electrochemistry- the interchange of chemical and electrical energy- is about to play a major role in energy production. As a clean, sustainable energy technology, direct ethanol fuel cells (DEFCs) have emerged as highly promising low carbon power sources for vehicles and as alternatives to rechargeable batteries in portable electronic devices. Yet, the commercialization of DEFCs is hindered by their low anode catalyst activities and the production of partial oxidation byproducts. In addition, proton exchange membranes-DEFCs are considered too bulky and costly, and they can be damaged by high concentrations of ethanol, known as the ethanol crossover effect. Our long-term objective is to develop membraneless mixed-reactants DEFCs (novel technology) with efficiency higher than 60%. Over the next five years, the main objective of our work is to develop and gain insights in the synthesis-structure-catalytic activity relationships of novel nanostructured highly active and efficient multicomponent anode catalysts for the electrocatalytic oxidation of ethanol (Theme I). Efforts will be focused on the addition of co-catalysts to platinum. We will choose materials composed of abundant and inexpensive metal oxide materials combined with ultra-low amounts of platinum and rhodium. We expect to discover the optimal structural arrangements of the atoms of the three components in the surface and bulk of the final active catalyst to maximize activity and selectivity. We will also develop selective cathode catalyst that is electroactive towards oxygen reduction reaction while tolerant to high concentrations of ethanol (Theme II). Considering that the size of oxygen molecule is much smaller than that of ethanol, our idea is develop a superficial material layer through which oxygen molecules can easily diffuse and be reduced at the platinum beneath layer surface while ethanol molecules remain impeded at the surface of the superficial layer. Like this higher ethanol concentrations could be used and superior electrochemical performance would be achieved. The results of this proposal will address Canada's research priority in the development of advanced nanomaterials based electrochemical clean/green technologies to deal with increasingly critical energy and environmental challenges as well as climate change, while training highly qualified personnel to exploit these opportunities. As to the fundamental issues, these studies will assist in establishing firm correlations between interfacial structures, compositions, and understanding of mechanistic aspects of new classes of catalytic materials. In addition, this proposed research program will be important to commercial applications in Canada such as, consumers' portable electronics and transport, or to specific users for road safety fuel cell-based sensors for ethanol detection.