Eco-friendly synthesis of carbon nanomaterials from pumpkin waste

Abstract Waste management remains a major environmental challenge in the food sector, making the recovery and reuse of organic waste essential. This study presents a novel and optimised approach to converting pumpkin peel waste into high-quality carbon material using microwave-assisted pyrolysis (MAP), without the use of chemical additives or metal doping. The resulting carbon nanomaterial exhibits desirable characteristics, including crystalline to semicrystalline carbon nanoparticles (lattice spacing of 2.29 Å), microporosity of 29.1 m²/g, and a pore diameter of 3.7 nm, along with enhanced electron transfer kinetics (Rct = 563 Ω). This carbon material was employed to modify a screen-printed carbon electrode (SPCE) for the electrochemical detection of nitrite. The modified electrode shows a significant improvement in electrochemical response, with an increase in current output from 20 µA to 30 µA, resulting in higher conductivity, a broader Linear detection range, and a lower detection Limit of 10 µM. This work demonstrates a promising result for upcycling food waste into functional nanomaterials, offering both environmental benefits and practical applications in electrochemical sensing technologies. Graphical abstract