State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology , Beijing 100029, P. R. China.
ACS Appl Mater Interfaces. 2018 Feb 28;10(8):7052-7060. doi: 10.1021/acsami.7b16549. Epub 2018 Feb 15.
Developing atomic-level transition oxides may be one of the most promising ways for providing ultrahigh electrocatalytic performance for oxygen reduction reaction (ORR), compared with their bulk counterparts. In this article, we developed a set of atomically thick CoO layers covered on Co nanoparticles through partial reduction of CoO nanoparticles using melamine as a reductive additive at an elevated temperature. Compared with the original CoO nanoparticles, the synthesized CoO with a thickness of 1.1 nm exhibits remarkably enhanced ORR activity and durability, which are even higher than those obtained by a commercial Pt/C in an alkaline environment. The superior activity can be attributed to the unique physical and chemical structures of the atomic-level oxide featuring the narrowed band gap and decreased work function, caused by the escaped lattice oxygen and the enriched coordination-unsaturated Co in this atomic layer. Besides, the outstanding durability of the catalyst can result from the chemically epitaxial deposition of the CoO on the cobalt surface. Therefore, the proposed synthetic strategy may offer a smart way to develop other atomic-level transition metals with high electrocatalytic activity and stability for energy conversion and storage devices.
开发原子级别的过渡氧化物可能是提供超高性能氧还原反应（ORR）电催化剂的最有前途的方法之一，与它们的体相比。在本文中，我们通过使用三聚氰胺作为还原剂在高温下部分还原 CoO 纳米粒子，开发了一组覆盖在 Co 纳米粒子上的原子层厚的 CoO 层。与原始的 CoO 纳米粒子相比，厚度为 1.1nm 的合成 CoO 表现出显著增强的 ORR 活性和耐久性，甚至高于在碱性环境中获得的商业 Pt/C。优异的活性可归因于原子层中由于逃逸的晶格氧和丰富的配位不饱和 Co 导致的独特物理和化学结构，表现为缩小的带隙和降低的功函数。此外，催化剂的出色耐久性可归因于 CoO 在钴表面的化学外延沉积。因此，所提出的合成策略可能为开发用于能量转换和存储设备的具有高电催化活性和稳定性的其他原子级过渡金属提供了一种明智的方法。
