Electrocatalytic property of nitrogen-doped graphite-supported CeO₂-CoO_x

Abstract

Ceria has been widely used as a catalyst in photocatalysis, automobile exhaust purification, and organic degradation. However, ceria has poor intrinsic catalytic performance and usually requires modifications. In this study, N-doped graphite was used as a substrate, and then CeO2-CoOx was attached to N-doped graphite. Afterward, the effects of the recombination with N-doped graphite and those of Co doping on the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic ability of CeO2 were studied. The experimental results showed that the electrocatalytic performance of CeO2-CoOx/N-rGO is higher than that of pure CeO2 and CeO2/N-rGO. After the N-doped graphite recombination, the number of transferred electrons increased at high potential, which fully illustrates that graphite can effectively reduce the overpotential of ORR. The 0.56 eV shift of the C1s in CeO2-CoOx/N-rGO to high binding energy revealed that CeO2-CoOx and N-rGO were combined with each other through covalent bonds. In addition, the increased pyridine nitrogen of N-rGO after the recombination improved the electrocatalytic performance of CeO2-CoOx/N-rGO. Overall, the catalytic ability of CeO2 was greatly improved, and the modified CeO2-CoOx/N-rGO composite showed better catalytic performance for the ORR and OER compared with Pt/C and RuO2.

Ce-modified Co–Mn oxide spinel on reduced graphene oxide and carbon black as ethanol tolerant oxygen reduction electrocatalyst in alkaline media

“…It has become more and more evident recently that the combination of CeO 2 and Co/Mn spinels can have a positive effect on the ORR activity. [15][16][17]19,22,[24][25][26]29,30 The exible transition in the Ce 3+ /Ce 4+ redox couple (eqn (5)) and the existing 4f orbital of Ce together with the unique properties like structural stability and rich redox reactions of the spinel make this obvious. 15,17,30,31 CeO 2…”

“…Numerous studies in which cobalt or manganese oxides were either doped with cerium in the crystal and/or CeO 2 was generated for synergistic effects reveal an improvement in electrocatalytic activity. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] For example, Wang et al 22 found that Ce doping and CeO 2 decoration of Co 3 O 4 results in a higher ORR activity attributed to decreased particle size, enhanced conductivity, a higher Co 3+ /Co 2+ ratio and the synergetic interaction between CeO 2 and Co 3 O 4 . These effects can be related to the exible transition in the Ce 3+ /Ce 4+ redox couple and the existing 4f orbital of Ce facilitates electron transfer and provides active sites.…”