Catalytic Engineering of Waste Biomass‐Derived Nano‐Carbon for Ultra‐Low Detection of Lead and Mercury Ions

Abstract Sensor‐based technologies are driving a revolution in environmental monitoring, enabling precise measurement and effective pollutant management. Accurate quantification of environmental pollutants is the foundation upon which remediation, protection, and policy enforcement solutions are built. These technologies ensure that environmental management strategies are data‐driven, precise, and responsive to real‐time conditions. This study has explored the sustainable yet effective development of sensor from parthenium hysterophorus waste biomass for detecting lead and mercury ions. The catalytic graphitization process has effectively converted plant biomass into graphitized carbon. A metal catalyst and specific functional groups are introduced to enhance the conductivity and sensitivity of the nanocomposite. The porous network of graphene‐like nanostructure, along with high crystallinity, is successfully developed, where the presence of silver, nitrogen, sulfur, and oxygen is confirmed through EDS and XPS. FE‐SEM images represent the layered structure of nanocomposite, while TEM has indicated the network of carbon structure with the distribution of silver nanoparticles on it. XRD spectra have shown a clear peak at 26°, which indicates the layered architecture with high crystallinity. CV study was also conducted to study the redox behavior of lead and mercury ions. DPASV study was conducted to study the sensitivity of lead and mercury ions. Nanocomposite also shows high selectivity in the mixed metal solution. It also shows high sensitivity with detection limits of 600 and 300 nM for lead and mercury ions. At the same time, a real sample study also showed a good response, where a detection limit of 400 nM was obtained for lead in tap water. The RSD calculated after studying the response with three different electrodes is 3.2%. The nanocomposite also represent high stability even after 60 days of storage. This study paves the way for developing sustainable nanomaterials from waste biomass for sensing heavy metal ions.