High-Purity V2O5 Nanosheets Synthesized from Gasification Waste: Flexible Energy Storage Devices and Environmental Assessment

Gasification waste, also known as carbon soot, is solid industrial waste from the bottom residual of an oil refinery and contains a substantial amount of toxic vanadium. In this work, we report an environmentally responsible pathway to harvest toxic vanadium from gasification waste, and the extracted vanadium can be utilized to synthesize high-purity V 2 O 5 nanosheets for the fabrication of flexible, bendable, efficient supercapacitors. The carbonaceous waste was first rinsed with alkaline solution to leach out toxic vanadium. The vanadium-rich leachate was next utilized to synthesize high-quality V 2 O 5 crystals with comparable purity (>98%) and crystallinity to commercial products. Two-dimensional V 2 O 5 nanosheets were further crystallized by hydrothermal treatment for the fabrication of high-performance electrochemical electrodes. The V 2 O 5 electrodes derived from gasification waste demonstrated similar specific capacitance (172 F g –1 ) to those from commercial V 2 O 5 (173 F g –1 ). The waste-derived V 2 O 5 nanosheets were further mixed with leached carbon nanoparticles for the fabrication of a symmetric, bendable, and flexible supercapacitor. The waste-derived V 2 O 5 supercapacitor was able to be bent up to 160° and retained its specific capacitance. An environmental impact assessment was finally conducted to evaluate the environmental impacts of producing V 2 O 5 crystals from gasification waste (in terms of the damage to human health, ecosystem diversity, and resource availability). The waste-derived approach was compared with traditional mining processes and showed a large improvement in all three endpoint damage categories.