One step in-situ synthesis of Co@N, S co-doped CNTs composite with excellent HER and ORR bi-functional electrocatalytic performances

Heteroatoms such as nitrogen/sulfur atoms are efficient for boosting the electrocatalytic performances of carbon materials. Meanwhile, loading transition metals/metal compounds on carbon materials also can significantly enhance the electrocatalytic activities of carbon materials. Despite the high electrocatalytic activities and broad applications of nitrogen, sulfur co-doped carbon nanotubes (CNTs) composites according to the reported literature, the synthesis processes of them are relatively complex. Herein, for the first time we report a facile method to synthesize Co encapsulated, N, S co-doped CNTs (Co-NSCNTs) composite using thiourea and cobalt acetate through heat treatment. These kinds of CNTs are actually curled and stacked by multiple layers of N, S co-doped nanosheets, which possess an unenclosed structure and thereby a very large specific surface area (276.2 m2 g−1). Most of the Co nanoparticles (∼30 nm) are well encapsulated inside the N, S co-doped CNTs, forming a unique Co, N, S tri-doped CNTs composite. In this composite, the doping amount of N and S atoms reaches 8.1 and 2.2 at.% (from XPS results) respectively and the Co element reaches 8.45 wt.% (ICP). Owing to the special structure and composition, the Co-NSCNTs exhibit very high catalytic performances towards HER and ORR in both acidic and alkaline electrolytes.