Unveiling the role of strontium in 1D SrxRu1-xO2-x compound oxide nanofibers for high-performance supercapacitor

Abstract

Hydrous ruthenium oxide (RuO2) has been considered a potential electrode for supercapacitors. However, RuO2 is not easy to be hydrous, which impedes advancement in RuO2-based supercapacitors. Here, strontium cation (Sr2+) - with a lower oxidation state than Ru4+ - doping effects on improving the capability of RuO2 to be hydrous are reported. The Sr2+ doping in the RuO2 was simply possible using electrospinning and subsequent calcination, affecting hydrous properties and promoting miniaturization of nanograins in one-dimensional (1D) nanofibers. The compositions of hydrous Sr2+-doped RuO2 (H-SrxRu1-xO2-x) nanofibers were optimized considering correlations between synthesis temperature and degree of hydration. It was found that the H-Sr0.2Ru0.8O1.8 nanofibers synthesized at 400 °C were hydrous compared with the pristine RuO2 and H-Sr0.1Ru0.9O1.9 nanofibers. The H-Sr0.2Ru0.8O1.8 nanofibers (400) could possess the smallest nanocrystallites, increasing electrochemically active surface area and satisfying specific capacitance of 612.6 A/g at a scan rate of 50 mV s-1.