Upcycling waste lotus seed heads into iron oxide-impregnated activated carbon for CO2 adsorption and supercapacitor application

Abstract

Background

CO₂ emissions are a major concern due to their impact on global warming scenarios. The increased CO₂ level in the atmosphere demands the creation of effective, environmentally friendly methods to reduce its impact.

Methods

In this study, we investigated the use of iron oxide on carbon surfaces as a highly effective CO₂ adsorbent. Impregnating iron oxide on a carbon matrix generated from lotus seed heads increased the surface chemistry and active sites. The surface properties and chemical composition of the material were investigated using X-ray photoelectron spectroscopy, Fourier Transform infrared spectroscopy, and Brunauer-Emmett-Teller.

Significant findings

The activated carbon prepared from lotus seed heads at 800°C exhibits an enhanced surface area of 1179.657 m² g^-1, with a micropore volume of 0.461 cm³ g^-1. Following the impregnation process, the surface area decreased, indicating successful impregnation of iron oxide within the carbon matrix. The resulting sorbent material leverages the advantages of both physical and chemical adsorption, utilizing the micropores in the carbon matrix alongside the catalytic properties of iron compounds. Research findings indicate that the L-Fe material significantly improves the CO₂ adsorption rate to 62.16 mg/g, due to the stronger interaction between CO₂ molecules and the active surface sites. Furthermore, the adsorbent material exhibits notable durability and reusability across multiple adsorption-desorption cycles, underscoring its suitability for large-scale industrial applications. Concurrently, the carbon material enhanced with iron oxide exhibited outstanding capabilities as an electrode component, showcasing a charge storage capability of 153.5 F g^-1 and exceptional stability of 86.84% for 5000 charge-discharge cycles. The material shows remarkable reusability for CO₂ sequestration and durability in energy storage, highlighting its versatile capabilities. These findings underscore the potential of carbon infused with iron oxide as an eco-friendly and cost-effective solution for addressing global environmental challenges while promoting advancements in renewable energy.