氮掺杂还原氧化石墨烯/四氧化三钴双功能催化剂的制备及表征

采用尿素作为氮源,通过热退火法制备氮掺杂还原氧化石墨烯,然后以乙酰丙酮钴作为钴源通过水热法制备氮掺杂还原氧化石墨烯/四氧化三钴杂化纳米片作为催化氧还原和氧析出反应的双功能催化剂。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线电子能谱仪(XPS)等对其进行形貌结构表征,通过旋转圆盘电极等电化学测试对其电催化性能进行分析,可以看出该催化剂具有良好的氧还原和氧析出催化性能。

Preparation and Characterization of Nitrogen-Doped Reduced Graphene Oxide/Cobalt Tetraoxide Bifunctional Catalyst

Urea was used as the nitrogen source precursor,nitrogen-doped reduced graphene oxide was prepared by thermal annealing,and then nitrogen-doped reduced graphene oxide/tri-cobalt-doped hybrid nanosheet was prepared by hydrothermal method using cobalt acetylacetonate as cobalt source.Reduction and oxygen evolution of the bifunctional catalyst.Firstly,the microstructures were characterized by scanning electron microscope(SEM),transmission electron microscopy(TEM)and energy dispersive X-ray spectroscopy(EDS).The catalysts were found to have a unique layered mesoporous structure.The formation of spinel tetraoxide with spinel structure in the catalyst was verified by X-ray electron spectrometer(XPS)and X-ray diffractometer(XRD).Thermogravimetric analysis indicated that the content of nitrogen-doped graphene and tricobalt tetroxide in the catalyst was 68.43%and 31.57%(w/w),respectively.Electrochemical tests such as rotating disk electrodes showed that the catalyst exhibited superior oxygen reduction and oxygen evolution catalytic properties.In an alkaline environment,the initial potential,half-wave potential,and limiting current density were 1.171 V,0.718 V,and4.3 mA·cm-2,respectively.The Koutecky-Levich equation shows that the catalyst directly reduces oxygen by a four-electron process.In water,the catalytic efficiency was high.The oxygen evolution catalytic performance test showed that the overpotential at the current density of 10 mA·cm-2 was 1.789 V,and the Tafel slope was 134 mV·dec-1,which had good oxygen evolution kinetics.The difference of overpotential(ΔE)was 1.071 V,which was superior to common dual-function catalysts.