Khalily Mohammad Aref, Patil Bhushan, Yilmaz Eda, Uyar Tamer
Institute of Materials Science and Nanotechnology, National Nanotechnology Research Center (UNAM), Bilkent University Ankara 06800 Turkey
Laboratory of Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology, University of Twente Enschede 7500 AE The Netherlands
Nanoscale Adv. 2018 Dec 26;1(3):1224-1231. doi: 10.1039/c8na00330k. eCollection 2019 Mar 12.
The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are considered as the two crucial reactions in key renewable-energy technologies including fuel cells and water splitting. Despite promising research progress in the preparation of various non-noble metal based electrocatalysts, it is still highly challenging but desirable to develop novel fabrication strategies to synthesize highly active and cost-effective ORR/OER bifunctional electrocatalysts in a precisely controlled manner. Herein, we report atomic layer deposition (ALD) of highly monodisperse CoO nanocrystals of different sizes on N-doped electrospun carbon nanofibers (nCNFs) as high performance bifunctional catalysts (Co@nCNFs) for the ORR and OER. Co@nCNFs (with an average CoO particle size of ∼3 nm) show high ORR performance exhibiting an onset potential of 0.87 V with a low Tafel slope of 119 mV dec approaching that of commercial Pt/C. Similarly, the Co@nCNF electrocatalyst showed remarkable catalytic activity in the OER. The turnover frequency (TOF) value determined at an overpotential of 550 mV for the Co@nCNFs is ∼0.14 s which is 3 and 15-fold higher than those of bulk Co (∼0.05 s) and the standard state-of-the-art IrO (0.0089 s) catalyst, respectively. This work will open new possibilities for fabrication of inexpensive non-noble metal materials in highly controlled manner for applications as bifunctional ORR/OER electrocatalysis.
氧还原反应（ORR）和析氧反应（OER）被认为是包括燃料电池和水分解在内的关键可再生能源技术中的两个关键反应。尽管在制备各种非贵金属基电催化剂方面取得了有前景的研究进展，但开发新颖的制备策略以精确控制的方式合成高活性和成本效益高的ORR/OER双功能电催化剂仍然极具挑战性但却很有必要。在此，我们报道了在氮掺杂的电纺碳纳米纤维（nCNFs）上原子层沉积（ALD）不同尺寸的高度单分散CoO纳米晶体，作为用于ORR和OER的高性能双功能催化剂（Co@nCNFs）。Co@nCNFs（平均CoO粒径约为3 nm）表现出高ORR性能，起始电位为0.87 V，低塔菲尔斜率为119 mV dec，接近商业Pt/C。同样，Co@nCNF电催化剂在OER中表现出显著的催化活性。在550 mV过电位下测定的Co@nCNFs的周转频率（TOF）值约为0.14 s，分别比块状Co（约0.05 s）和标准的最先进IrO（0.0089 s）催化剂高3倍和15倍。这项工作将为以高度可控的方式制备廉价的非贵金属材料用于双功能ORR/OER电催化应用开辟新的可能性。
