Electrocatalytic Activity of Cobalt Doped Ceria Nanoparticles

It is very difficult for single ceria to be used as an electrocatalyst because of its relatively poor electron conductivity and rare number of oxygen vacancy. Recently, it has been studied in the field of CO catalysis by doping transition metallic or non-metallic elements to improve the catalytic ability of ceria, while recent research has demonstrated that many oxides containing cobalt display better electrocatalytic activity. In this study cobalt doped ceria nanoparticles were prepared by homogeneous precipitation method. The electrochemical tests show that the optimum doping molar ratio is 20mol% for ORR and OER catalytic effect. After 10 hours of catalysis, the current density of ORR and OER decrease by about 20% and 5%, respectively, far below the corresponding values when noble metal and undoped cerium oxide nanoparticles were used as catalysts, and it indicated that the prepared catalyst owns good catalytic stability. In addition, XPS and other tests show that the decrease of charge transfer impedance (the improvement of electronic conductivity), the increase of active oxygen species, and the increased oxygen vacancies after doping are main reasons for improved catalytic performance. Therefore, doping cobalt greatly enhanced electrocatalytic properties of ceria nanoparticles are greatly enhanced by doping cobalt, providing guidence for other ionic conductors employed as bifunctional electrocatalysts.