脊椎状NiCo_2O_4纳米棒的制备及其析氧和氧还原性能研究

Facile Synthesis of Spine-like NiCo_2O_4 Nanorods as Highly Efficient Electrocatalysts for Oxygen Reduction and Evolution Reactions

以水热法并进一步焙烧合成脊椎状NiCo_2O_4纳米棒,通过透射电子显微镜(TEM)、 X射线衍射仪(XRD)、 X射线光电子能谱仪(XPS)和热重分析仪(TG)等来表征其结构形态及热稳定性.采用线性扫描法(LSV)、循环伏安(CV)研究所制备催化剂的在玻碳和旋转圆盘电极上的电催化活性:在0.1 mol·L^(-1) KOH溶液中的电催化析氧反应(OER)和电催化氧还原反应(ORR).研究结果表明,所制备的脊椎状NiCo_2O_4纳米棒有大量的不饱和态, 200℃焙烧制备的脊椎状NiCo_2O_4纳米棒析氧过电位最小可达309 mV, Tafel斜率145.6 mV/dec,其氧还原极限电流密度在1600 rmp可达到5.095 mA·cm^(-2),电子转移数在3.2～3.8之间,接近四电子转移机理,其优良电化学性能可能是由于暴露了更多的边缘缺陷的缘故.

Spine-like NiCo2O4 nanorods have been synthesized by a facile hydrothermal method, followed by calcination process. The morphology and stability of the as-prepared catalysts were characterized by transmission electron microscope(TEM), X-ray photoelectron energy spectrum(XPS), X-ray diffraction(XRD) and thermogravimetric analysis(TG) techniques. The oxygen evolution reaction(OER) and oxygen reduction reaction(ORR) perfor-mance of as-prepared NiCo2O4 were studied in 0.1 mol·L-1 KOH solution using linear sweep voltammetry(LSV) with GC and rotating disk electrode, respectively. After testing, the lowest overpotential of 309 mV and Tafel slope of 145.6 mV/dec were achieved for OER, moreover, the highest current density could reach 5.095 mA·cm-2 at 1600 rmp for ORR. The electron transfer numbers were range from 3.2 to 3.8, close to four electron transfer mechanism. This indicates that electrocatalytic properties of the NiCo2O4 electrode is excellent, which probably due to the unique structural feature with more edge defect.