Synthesis and utilization of RuO2•xH2O nanodots well dispersed on poly(sodium 4-styrene sulfonate) functionalized multi-walled carbon nanotubes for supercapacitors

RuO2 center dot xH(2)O nanodots highly dispersed onto the surfaces of poly(sodium 4-styrene sulfonate) (PSS) functionalized multi-walled carbon nanotubes (FMWCNTs) were successfully synthesized via a polymer-assisted technique under mild hydrothermal conditions. Here, PSS served as a bifunctional molecule both for solubilizing and dispersing MWCNTs into aqueous solution and for tethering Ru3+ to facilitate the subsequent uniform formation of RuO2 center dot xH(2)O nanodots on their surfaces. The dependence of electrochemical utilization of RuO2 center dot xH(2)O nanodots on their dispersity was evidenced by cyclic voltammetry results. The maximum specific capacitance of 1474 F g(-1) and electrochemical utilization of 71% for the Ru species were obtained from RuO2 center dot xH(2)O/FMWCNTs nanocomposite with 10 wt% RuO2 center dot xH(2)O. And even for the 45 wt% RuO2 center dot xH(2)O loading, the utilization of 34% still could be delivered, much higher than that of just 23% for the bare RuO2 center dot xH(2)O nanodots. Such good supercapacitive performance of the nanocomposites should result from the high dispersity of the electroactive RuO2 center dot xH(2)O nanodots on the FMWCNTs, resulting in the abundant electroactive surface atoms contacted by the H+ ions through the three-dimensional mesoporous conducting matrix easily even in the case of the high loadings of ruthenium oxide.