Bi-functional green-synthesis of Co3O4 NPs for photocatalytic and electrochemical applications

Abstract

Wastewater of industries, which is polluted with different dyes is becoming a severe issue, which should be tackled on priority bases such as to provide an eco-friendly environment. In addition to this, in search of an efficient green synthesized capacitive electrode material, we have synthesized cobalt oxide (Co3O4) nano-materials by employing green chili and sunflower seeds extracts. The as synthesized samples are labeled as Co-P, Co-GC and Co-SF. The successful fabrication of these samples was tested by X-ray diffraction (XRD), scanning electron microscope (SEM), Xray photoelectron spectroscope (XPS). These tests have explored successful fabrication of Co3O4-based samples comprised on nanoparticles (NPs) in the range of 35–45 nm. Optical properties were studied by UV–vis spectroscope and Co-SF sample has exhibited lowest energy band gap i.e 2.41 eV. Photoluminescence (PL) analysis has explored that Co3O4 NPs prepared by sunflower extracts have offered lowest recombination rate. Among of Co-P, Co-GC and Co-SF photocatalysts, Co-SF has shown excellent photodegradation activity, which is 90% against a water pollutant name as methylene blue (MB) under UV–Vis light. This sample also has shown a good catalytic stability i.e 80.7%. Moreover, for electrochemical performance analysis, cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopic (EIS) tests were also performed. Among of Co-P, Co-GC and Co-SF samples, Co-SF sample has offered 1080.32 F/g specific capacitance and 86.70% capacitance retention at higher scan rate i.e 10 A/g. Additionally, this optimized sample has also maintained 83.51% capacitance even after 5000 GCD cycles performed at 1 A/g, and good conductive nature. These extraordinary results have provided new platform for water purification and energy storage appliances.