Utilizing e-waste: Development of a room temperature ammonia sensing device featuring highly crystalline GdInO3 nanoballs on surface-active g-C3N4 Nanosheets

Advanced recycling methods are utilized to convert electronic waste into premium-grade products, highlighting its potential as a sustainable manufacturing resource. Motivated by the growing interest in 2-dimensional carbon structures and metal oxide nanocomposites, particularly in advancing gas sensor technology, this study embarks on an extensive investigation. The research meticulously examines the direct synthesis of a nanocomposite integrating graphitic carbon nitride (g-C ₃N ₄) and perovskite GdInO ₃, with a focus on its precise sensing capabilities towards ammonia (NH ₃). Through detailed characterization employing analytical and morphological techniques, the synthesized materials are elucidated. Notably, the nanoball-like morphology of GdInO ₃ is observed, stemming from the self-assembly of smaller nanoparticles into hierarchical structures, subsequently integrated into the g-C ₃N ₄ sheet. Evaluated chips of the e-waste circuit board (e-WCB) modified with the g-C ₃N ₄-GdInO ₃ nanocomposite exhibit an impressive response of 72 % towards 10-ppm ammonia, coupled with a response time of 63 seconds and a recovery time of 33 seconds at room temperature with the limit of detection (LOD) of 5.2-ppm. Furthermore, the sensor demonstrates outstanding sensitivity and selectivity towards NH ₃ compared to other interfering gases. The sensitivity of the composite material towards NH ₃ was high compared to the pristine materials, this would be because of its enhanced physical and chemical properties (higher active sites and microporosity), therefore the GdInO ₃-decorated g-C ₃N ₄ nanocomposite emerges as a promising candidate for the rapid, sensitive, and selective detection of NH ₃ under ambient conditions (30 °C).