Nitrogen and sulfur co-doped hollow carbon nanofibers decorated with sulfur doped anatase TiO2 with superior sodium and lithium storage properties

Nitrogen and sulfur co-doped hollow carbon nanofibers decorated with sulfur-doped anatase TiO2 (NS HCNF@S TiO2) has been synthesized through a simple hydrothermal reaction process followed by a calcination treatment, in which uniform sulfur-doped anatase TiO2 nanoparticles are firmly attached to the nitrogen and sulfur co-doped HCNF matrix. When the as-designed NS HCNF@S TiO2 composite is utilized as anode material for sodium and lithium storage, it delivers an enhanced electrochemical performance, which can be attributed to three synergic effects: (1) the core–shell and stable 3D network-like structures woven by nitrogen and sulfur co-doped HCNF in the NS HCNF@S TiO2 composite can accommodate stress from cycling and provide a beneficial conductive environment; (2) the doping of sulfur can lower the electronic resistance of TiO2 and increase the interlayer distance of carbon; (3) the uniform sulfur-doped anatase TiO2 attachment can further shorten the electron and ion pathways during electrochemical cycling. These findings indicate that the NS HCNF@S TiO2 composite has a great potential as TiO2-anode materials for sodium and lithium storage.