One-step hydrothermal synthesis of NiCo 2 S 4 –rGO as an efficient electrocatalyst for the oxygen reduction reaction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 2; no. 48; pp. 20990 - 20995
• Main Authors: Wu, Jianghong, Dou, Shuo, Shen, Anli, Wang, Xin, Ma, Zhaoling, Ouyang, Canbin, Wang, Shuangyin
• Format: Journal Article
• Language: English
• Published: 2014
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C4TA05159A

In this work, for the first time, we have developed a one-step hydrothermal method to synthesize a hybrid material consisting of NiCo 2 S 4 nanocrystals grown on reduced graphene oxide as an efficient nonprecious electrocatalyst for the oxygen reduction reaction (ORR) in alkaline medium. Our synthetic process here is quite simple, straightforward and environmentally benign. NiCo 2 S 4 –rGO shows significantly enhanced catalytic activity over rGO and NiCo 2 O 4 –rGO, and close reduction activity but much superior methanol tolerance and better durability than the commercial Pt/C catalyst. The half wave potential ( E 1/2 ) for the NiCo 2 S 4 –rGO hybrid is only about 62 mV more negative than that of the commercial Pt/C catalyst but 81 mV more positive than that of NiCo 2 O 4 –rGO, 116 mV than that of rGO. The superior performance of NiCo 2 S 4 –rGO is presumably attributed to a combination effect of mixed valence in transition metal composites favorable for O 2 to be absorbed/reduced and a synergetic effect resulting from NiCo 2 S 4 and rGO. The advantages over NiCo 2 O 4 –rGO might be ascribed to the inverse spinel crystal structure of NiCo 2 S 4 , its relative higher conductivity, and the fact that Na 2 S serves both as the S source and reducing agent facilitating an increase in the hybrid catalytic activity.