基于金属复合纳米线阵列直接乙醇燃料电池阳极材料的可控制备及其催化机理研究

Research and development of high-efficiency and low-price electrocatalysts for direct ethanol fuel cell (DEFC) application play a very important role in DEFC commercialization and relieving fuel shortage now and in the future. We have previously reported a kind of Pd nanowire arrays which showed excellent electrocatalytic activity for ethanol electro-oxidation (Adv. Mater. Vol 19, Times Cited: 196, one of the top 1% of most highly cited papers in chemistry worldwide).This work paves the way for this proposal. Based on these results, Pd-Au and Pd-Pt bimetallic NWAs were fabricated according to this method, and the bimetallic NWAs exhibited synergistic effect between the metals which improved the electrocatalytic activity of the NWAs towards ethanol oxidation. In view of its excellent performance in ethanol eletrocatalytic oxidation and its potential applications in DEFC, we herein, propose to design and fabrication of a series of Pd based bi- and trimetallic nanowire arrays for DEFC application. The as-fabricated nanowire arrays will be modified via methods such as galvanic replacement, electrodeposition, and so on. Several characterization methods such as SEM, TEM, EDS and XPS will be employed to characteriz the as-fabriacated NWAs.The electrocatalytic activity, the anti-poison ability to carbon monoxide, and the sustainability of the as-fabricated nanowire arrays towards ethanol oxidation will be examined by electrochemical methods.The electrocatalytic oxidation reaction of ethanol on the substrates will be monitored by in-situ FTIR and in-situ Raman spectroelectrochemistry. As a result, the oxidation products on NWAs surface will be deterimined and, the aging mechanism of the NWAs during electrocatalytic oxidation of ethanol will also be studied by by in-situ FTIR and in-situ Raman spectroelectrochemistry. This proposal is aiming to, on one hand, develop high efficient, stable, low- or non-noble metal loading anodes for DEFC applictaion; on the other, provide theory and experimental bases for further develop/improve materials in DEFC application.

高效、低成本直接乙醇燃料电池（DEFC)催化剂的开发，对DEFC的商业化发展及解决当前的能源问题具有深远意义。课题组前期研究制备了一种基于Pd纳米线阵列的具有良好催化活性的乙醇燃料电池阳极催化剂（Adv. Mater.19卷23期, 被引用196次，是ESI学科全球前1%的高被引论文），是开展本项目可靠的前期基础。本项目旨在设计和制备一系列尺寸可控、高度有序、分散性好的以Pd为基础的金属复合纳米线阵列，并通过电置换反应、电沉积等方法对这些纳米线阵列进一步修饰。利用SEM、TEM和EDS及XPS等技术表征纳米线阵列，观测纳米线阵列的结构和组成。研究复合纳米线阵列对乙醇氧化的电催化氧化活性及电催化机理，并对其抗中毒能力和耐久性进行研究。希望能够开发出具有实际应用价值的DEFC阳极材料，并为开发出更为高效、稳定、低贵金属担载量或无贵金属的DEFC阳极材料，提供实验依据和理论基础。

本项目旨在研制高效低成本的电催化乙醇氧化催化材料。在研究初期，课题组成员先优化了阳极氧化铝（AAO）模板的制备工艺，并在此基础上制备出了不同孔径的AAO模板，在这些AAO模板的基础上制备了一系列尺寸的铜基纳米线阵列，但铜基纳米线阵列在修饰上贵金属（如铂、钯等）后易倒伏、塌陷，电催氧化乙醇效果不好。鉴于此，课题组成员制备出表面洁净、尺寸均一可控、形貌规则的氧化亚铜（立方体、八面体、十四面体）颗粒和枝状银材料，以这些材料为模板，利用电置换反应对它们进行改性研究，置换上Pt、Pd、Au、Ru等贵金属元素，利用ICP、XRD、XPS、SEM、TEM/STEM等表征手段对所制备材料的成份、结构和形貌进行了表征。利用电化学手段，系统研究了经电置换修饰后得到的Cu2O@PdxRuy、AgPdxRuy、AgPtxRuy电极材料对乙醇的电催化氧化活性。研究了不同组分、尺寸及金属复合方法对纳米线阵列对电催化氧化乙醇的催化活性、抗毒性和耐久性的影响，并利用现场拉曼光谱电化学研究了乙醇在AgPtxRuy电极上的电催化氧化过程。研究发现了Cu2O@PdxRuy、AgPdxRuy、AgPtxRuy系列材料在碱性条件下电催化乙醇氧化方面的优异性能，这些材料同时拥有贵金属担载量少、催化活性高、抗CO毒化性好、稳定性好、制备方法简单等优点。研究结果一方面证实了电置换反应是一种方便、有效的材料改性方法，可以在保留模板材料框架结构的基础上，得到贵金属担载量较少的空心（多孔）结构，不仅提高了材料的比表面积，也增加了材料的传质作用；另一方面也证明了银材料在电催化氧化乙醇中的辅助催化功能。