Wang Lei, Lin Chong, Huang Dekang, Zhang Fengxing, Wang Mingkui, Jin Jian
Nano-Bionics Division and i-LAB, Suzhou Institute of Nano-Tech & Nano-Bionics, Chinese Academy of Sciences , Suzhou, Jiangsu 215123, China.
ACS Appl Mater Interfaces. 2014 Jul 9;6(13):10172-80. doi: 10.1021/am5014369. Epub 2014 Jun 18.
Oxygen electrochemistry has been intensely studied in the pursuit of sustainable and efficient energy conversion and storage solutions. Over the years, developing oxygen electrode catalysts with high activity and low cost remains a great challenge, despite tremendous efforts. Here, NixCo1-x(OH)2 is used as a bifunctional electrocatalyst for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The effect of its compositions (x = 1, 0.55, 0) and morphologies (including both multilayer and single-layer NixCo1-x(OH)2) on catalytic activity is studied systematically in order to optimize the oxygen-electrochemical performance of 3d-M (M = Ni and Co) metal hydroxides. Our results show that the compositions of NixCo1-x(OH)2 has a great influence on overpotentials by comparing multilayer Co(OH)2, Ni0.55Co0.45(OH)2, and Ni(OH)2 for OER. Multilayer Ni(OH)2 exhibits the lowest overpotential of 324 mV at the current density of 5 mA/cm(2). Moreover, the overpotential could be greatly lowered by using single-layer NixCo1-x(OH)2. Single-layer Ni(OH)2 nanosheet manifests 71 mV overpotential decrease (5 mA/cm(2)) and a factor of 14 turnover frequency increase as compared to multilayer Co(OH)2 for OER. As for ORR, multilayer Co(OH)2 shows the best activity among multilayer NixCo1-x(OH)2. Similar to OER, single-layer NixCo1-x(OH)2 demonstrates enhanced ORR activity over multilayer NixCo1-x(OH)2. Single-layer Co(OH)2 exhibits the best catalytic activity and 3.7 electrons are transferred during oxygen reduction process. The successful identification of the composition and morphology effect of 3d metal hydroxides on electrocatalytic performance provides the foundation for rational design of active sites for high-performance catalyst for both OER and ORR.
为了寻求可持续且高效的能量转换与存储解决方案，人们对氧电化学展开了深入研究。多年来，尽管付出了巨大努力，但开发具有高活性和低成本的氧电极催化剂仍然是一项巨大挑战。在此，NixCo1-x(OH)2被用作析氧反应（OER）和氧还原反应（ORR）的双功能电催化剂。系统地研究了其组成（x = 1、0.55、0）和形貌（包括多层和单层NixCo1-x(OH)2）对催化活性的影响，以优化3d-M（M = Ni和Co）金属氢氧化物的氧电化学性能。我们的结果表明，通过比较多层Co(OH)2、Ni0.55Co0.45(OH)2和Ni(OH)2用于OER时，NixCo1-x(OH)2的组成对过电位有很大影响。多层Ni(OH)2在电流密度为5 mA/cm(2)时表现出最低过电位324 mV。此外，使用单层NixCo1-x(OH)2可大大降低过电位。与多层Co(OH)2用于OER相比，单层Ni(OH)2纳米片的过电位降低了71 mV（5 mA/cm(2)），周转频率提高了14倍。对于ORR，多层Co(OH)2在多层NixCo1-x(OH)2中表现出最佳活性。与OER类似，单层NixCo1-x(OH)2比多层NixCo1-x(OH)2表现出更高的ORR活性。单层Co(OH)2表现出最佳催化活性，并且在氧还原过程中转移3.7个电子。成功识别3d金属氢氧化物的组成和形貌对电催化性能的影响，为合理设计用于OER和ORR的高性能催化剂的活性位点奠定了基础。
