Anchoring Hydrous RuO₂ on Graphene Sheets for High‐Performance Electrochemical Capacitors

Abstract

Hydrous ruthenium oxide (RuO2)/graphene sheet composites (ROGSCs) with different loadings of Ru are prepared by combining sol–gel and low‐temperature annealing processes. The graphene sheets (GSs) are well‐separated by fine RuO2 particles (5–20 nm) and, simultaneously, the RuO2 particles are anchored by the richly oxygen‐containing functional groups of reduced, chemically exfoliated GSs onto their surface. Benefits from the combined advantages of GSs and RuO2 in such a unique structure are that the ROGSC‐based supercapacitors exhibit high specific capacitance (∼570 F g−1 for 38.3 wt% Ru loading), enhanced rate capability, excellent electrochemical stability (∼97.9% retention after 1000 cycles), and high energy density (20.1 Wh kg−1) at low operation rate (100 mA g−1) or high power density (10000 W kg−1) at a reasonable energy density (4.3 Wh kg−1). Interestingly, the total specific capacitance of ROGSCs is higher than the sum of specific capacitances of pure GSs and pure RuO2 in their relative ratios, which is indicative of a positive synergistic effect of GSs and RuO2 on the improvement of electrochemical performance. These findings demonstrate the importance and great potential of graphene‐based composites in the development of high‐performance energy‐storage systems.

Supercapacitors specialities - Materials review

“…For pure ruthenium dioxide, the specific capacitance was 705.6 F/g whereas fore activated carbon a value of 119.3 F/g was obtained. A ruthenium oxide/graphene sheet composite was prepared in [88]. The fine RuO 2 particles with a size of 5-20 nm separate the graphene sheets.…”

Reduced graphene oxide–titania based platform for label-free biosensor

“…[25][26][27][28] It has been reported that the use of MOsN and GO nanocomposites may result in improved biosensor efficacy compared to when a single component is used. [29][30][31][32][33] Recently, a GO and titanium oxide (TiO 2 ) nanocomposite has been explored for the development of lithium ion batteries, photocatalysts and dye sensitized solar cells. 34 However, the RGO and MOsN composite have not yet been used for the fabrication of an electrochemical immunosensor.…”

Two-dimensional NiCo2O4nanosheet-coated three-dimensional graphene networks for high-rate, long-cycle-life supercapacitors

“…The pseudocapacitor undergoes reversible redox reaction that occurs in the electrode materials, such as metal oxides (RuO 2 , MnO 2 , Co 3 O 4 , NiCo 2 O 4 , CoMoO 4 , etc.) [7][8][9][10][11][12][13][14][15][16] and metal hydroxides (Co(OH) 2 , Ni(OH) 2 , etc. ); [17][18][19] it stores more charges and provides higher specific capacitance than does the EDLC.…”