Green electrochemical determination of capsaicin using a sensor constructed from cattle manure and spent battery graphite

The recycling of agricultural and electronic waste is pivotal to realizing the circular economy and green chemistry principles. This work successfully fabricated an electrochemical sensor using cattle manure and graphite rods from spent batteries, achieving quantitative determination of capsaicin (CAP) in pickled vegetables. Distinct from previous biochar-based sensors that focus on single waste streams or multi-step modifications, this work introduces a dual-waste synergistic upcycling strategy. The CoPc@SiO 2 @BC was prepared via a straightforward one-step pyrolysis process, which involved using cattle manure as the carbon source, and characterized by a suite of techniques. The CoPc@SiO 2 @BC was loaded onto a graphite rod recovered from spent batteries after simple surface treatment, forming a sensor that exhibited remarkable detection performance for CAP. It demonstrated a wide linear range from 0.5 to 1500 μM, a low detection limit of 0.26 μM, along with good selectivity, repeatability, and stability, confirming its capability for real-sample analysis. This synergistic utilization of dual waste resources not only reduces electrode fabrication costs but also enhances analytical sensing performance, thereby providing a novel pathway for developing green electrochemical sensing technologies.