Rationale of AgNPsmodified 3-dimensional grapheneas electrochemical sensor for the ultra-tracedetermination of mercury ions

Mercury (Hg) is a globally accepted highly toxic heavy metal pollutant and despite several important developments in the field, the determination of Hg²⁺ ions attrace levels in real-world samples is a challenge. Herein, the silver nanoparticles modified with three-dimensional graphene (AgNPs/3D-graphene) nanocomposite has been synthesised through a simple, cost-efficient, one-step freeze-casting routethat has been applied for highlysensitive determination of Hg²⁺. The 3D cellular network structure with continuous micrometersize open pores and uniformly decorated Ag nanoparticles with an average size of 30 nm has been suggested by the morphologies and structures of the as-prepared AgNPs/3D-Graphene nanocomposite. The AgNPs/3D-graphene nanocomposite-modifiedGCE (AgNPs/3D-graphene/GCE) exhibited a good linear relationship with Hg²⁺ concentrations ranging from 0.1 to 40 μg L⁻¹. The results showed that the limit of detection (LOD) of 0.08 μg L⁻¹ (S/N = 3), which is significantly less than the World Health Organization’s (WHO) recommended threshold. The method validation has been carried out using certified reference material (CRM). The sensitivity and stability from the composite has been achieved from the well scaffolded AgNPs all along the 3D-graphene network, which has made the method novel and stand out from othere reported. The suggested electrochemical sensor performed well in detecting Hg²⁺ in soil and borewell water samples as well as in clinical samples, which is crucial in safeguarding human health.