Direct Growth of MoS₂ Nanowalls on Carbon Nanofibers for Use in Supercapacitor

Direct growth of MoS₂ nanowalls on vapor grown carbon nanofibers (VGCNFs) has been achieved using a microwave-assisted hydrothermal (MAH) method under an acidic condition. The acidic condition was obtained through the addition of an HCl aqueous solution. We demonstrate that the HCl not only modifies the pH value for limiting the growth rate but also leads to the formation of NaCl, which is the key for the direct and unique growth of MoS₂ on the VGCNF surface. A growth mechanism is therefore proposed. The growth of MoS₂ onto the high electrically conducting VGCNF creates a unique structure that not only reduces the aggregation of MoS₂ but also improves the electrical conductivity of the resulting composite electrode. The MoS₂ nanowall/VGCNF composite shows Csp as high as 248 F g^-1 at 5 mV s^-1 and excellent electrochemical stability with a retention of 96% after 1,000 cycles at a high charge rate of 200 mV s^-1. The ease of composite fabrication and electrochemical stability suggest that the MoS₂ nanowall/VGCNF composite is a promising candidate electrode material for supercapacitor.