Sustainability from the start: biochar-based conductive inks enable the streamlined fabrication of green electroanalytical devices.

The design of low-cost and disposable printed electrodes (PEs) has garnered significant attention from the scientific community in recent years. It is crucial to achieve industrial scalability by addressing the cost of conductive inks and ensuring their environmentally friendly disposal. The utilization of biochar, a carbon-rich material derived from the pyrolysis of biomass waste, represents a promising and sustainable alternative to conventional carbon sources. In this study, peanut shell biochar produced with a low-cost pyrolytic kiln reactor was incorporated into conductive inks. As far as we know, biochar-based ink was used to fully fabricate stencil-printed electrodes for the first time. Three different chemical treatments were employed to activate the biochar and enhance its properties. XPS analysis and electrochemical characterization studies showed that organic solvents improved the characteristics of the biochar when compared to acid or alkaline activation treatments. As a proof of concept, the electrodes were used to detect paracetamol as a model analyte for emerging environmental contaminants. An analytical greenness metric (AGREE) was used to infer how environmentally friendly the analytical procedure is, yielding an overall score of 0.72, which indicates a high degree of environmental sustainability. This study underscores the importance of implementing simple strategies to obtain cost-effective PE, thereby promoting green analytical methods using recycled materials such as bio-waste-derived biochar. This approach may reduce dependence on non-environmentally friendly materials for sensor fabrication and contribute to addressing industrial waste recycling challenges.