Chemistry Department, Faculty of Science, Cairo University , Cairo 12613, Egypt.
Chemistry & Biochemistry-Physical & Theoretical Chemistry, Free Berlin University , 14195, Berlin, Germany.
ACS Appl Mater Interfaces. 2017 Jun 14;9(23):19766-19772. doi: 10.1021/acsami.7b01565. Epub 2017 May 31.
This study introduces a novel competent dendritic copper oxide-platinum nanocatalyst (nano-CuO-Pt) immobilized onto a glassy carbon (GC) substrate for formic acid (FA) electro-oxidation (FAO); the prime reaction in the anodic compartment of direct formic acid fuel cells (DFAFCs). Interestingly, the proposed catalyst exhibited an outstanding improvement for FAO compared to the traditional platinum nanoparticles (nano-Pt) modified GC (nano-Pt/GC) catalyst. This was evaluated from steering the reaction mechanism toward the desired direct route producing carbon dioxide (CO); consistently with mitigating the other undesired indirect pathway producing carbon monoxide (CO); the potential poison deteriorating the catalytic activity of typical Pt-based catalysts. Moreover, the developed catalyst showed a reasonable long-term catalytic stability along with a significant lowering in onset potential of direct FAO that ultimately reduces the polarization and amplifies the fuel cell's voltage. The observed catalytic enhancement was believed to originate bifunctionally; while nano-Pt represented the base for the FA adsorption, nanostructured copper oxide (nano-CuO) behaved as a catalytic mediator facilitating the charge transfer during FAO and providing the oxygen atmosphere inspiring the poison's (CO) oxidation at relatively lower potential. Surprisingly, moreover, nano-CuO induced a surface retrieval of nano-Pt active sites by capturing the poisoning CO via "a spillover mechanism" to renovate the Pt surface for the direct FAO. Finally, the catalytic tolerance of the developed catalyst toward halides' poisoning was discussed.
本研究介绍了一种新型的高效铜氧化物-铂纳米复合催化剂（nano-CuO-Pt），它被固定在玻碳（GC）基底上，用于甲酸（FA）电氧化（FAO）；这是直接甲酸燃料电池（DFAFC）阳极室内的主要反应。有趣的是，与传统的铂纳米颗粒（nano-Pt）修饰的 GC（nano-Pt/GC）催化剂相比，所提出的催化剂在 FAO 方面表现出了显著的改进。这是通过将反应机制引导到期望的直接途径来实现的，该途径产生二氧化碳（CO），同时减轻了其他不期望的间接途径，该途径产生一氧化碳（CO），这是一种潜在的毒物，会破坏典型的 Pt 基催化剂的催化活性。此外，所开发的催化剂表现出合理的长期催化稳定性，同时显著降低了直接 FAO 的起始电位，最终降低了极化并放大了燃料电池的电压。观察到的催化增强被认为源于双功能作用；纳米 Pt 代表 FA 吸附的基础，而纳米结构氧化铜（nano-CuO）则作为催化介质，促进 FAO 期间的电荷转移，并提供含氧气氛，以相对较低的电位促进毒物（CO）的氧化。此外，令人惊讶的是，纳米 CuO 通过“溢流机制”捕获中毒的 CO，从而捕获了纳米 Pt 活性位点，并对其进行了表面恢复，以更新 Pt 表面，从而促进了直接 FAO。最后，还讨论了开发的催化剂对卤化物中毒的催化耐受性。
