Green synthesis of nano-Co3O4 by Microbial Induced Precipitation (MIP) process using Bacillus pasteurii and its application as supercapacitor

Abstract

Cobalt oxide (Co3O4) has received great attention for its use in diverse applications in science and technology. The synthesis Co3O4 by ecofriendly green technological process is the great challenge in present day research.Considering the ecofriendly green technological application, the nano-Co3O4 has been synthesized by microbial induced precipitation (MIP) process in presence of Bacillus pasteurii (OD600; 1.2 × 107cells/mL). The Co3O4 particle was synthesized with different microbial amount (10–30 mL) and Co(NO3)2 (0.01M-1.0 M) by MIP process.The results were exhibited anoptimum yield (production yield 218 mg and conversion yield 61%) of “hybrid bio-Cobalt compound”formation at 0.1 M Cobalt ion and 30 mL of B. pasteurii. The XRD results reflect the formation of Co3O4 from “hybrid bio-Cobalt compound” after calcination at 550 °C. SEM and TEM micrograph of synthesized particle reflects the non-specific shape of particle size range at 10–31 nm. The electrochemical capacitive performance was studied through cyclic voltammetry (CV) and galvanostatic charge–discharge methods with 6.0 M KOH as electrolyte. The synthesized nano-Co3O4 after calcinated at 550 °C, leads to the best specific capacitance of 162.78 F g−1 at 1 mA cm−2constant current density. The energy density and power density of the synthesized were noticed as 4.58 Wh kg−1 and 64.29 W kg−1, respectively, which indicates the MIP synthesized nano-Co3O4 particle is supercapacitor. Thus, MIP process, an ecofriendly green technological process is capable to synthesized the supercapacitor nano-Co3O4 by Bacillus pasteurii and its can be applicable to energy and environment research sector.