文摘

We have reported a new reduced graphene oxide–bismuth oxide composite that can be used as a supercapacitor electrode. Bi2O3 was synthesized from bismuth nitrate pentahydrate and oxalic acid as a precipitating agent using a hydrothermal process in an aqueous graphene oxide suspension. Instead of mixing graphene oxide with bismuth oxide, we have developed a bismuth oxalate precipitation between the layers. As prepared, composite of hydrated bismuth oxalate and graphene oxide was converted to bismuth oxide and reduced graphene oxide by thermal decomposition in a muffle stove. The material exhibited the specific capacitance of 94?F/g at current density 0.2?A/g. Using the cyclic voltammetry, the specific capacitance was as high as 55?F/g at scan rate 5?mV/s over the potential range 0-?V. The material exhibited long-term cycle stability retaining 90?% specific capacitance after 3,000?cycles. Except Bi3+ ions present in Bi2O3, some amount of higher energy Bi5+ was confirmed.