Solution Process Synthesis of MoS₂–BSA–ZnO Nano–Bio Composite for Ultralow-Level Hg²+ Sensing Applications

Here, the synthesis of MoS2 nanosheet was performed by a novel approach “liquid-phase sonication technique” from MoS2 bulk powder to conjugate with ZnO nanoparticle and bovine serum albumin (BSA). This 2-D nano–bio composite MoS2–BSA–ZnO (MBZ) shows a tremendous potential to detect ultralow-level Hg
$^{{2}+}$
ions. An extensive study was employed on the synthesis of MoS2 and their nano–bio composite to investigate the effect of Hg
$^{{2}+}$
ions for sensing applications. The required characterization of the MBZ was carried out by XRD, field-emission scanning electron microscopy (FESEM), UV–Vis, and fluorescence (FL) spectroscopic technique prior to sensor fabrication. Absorbance spectra were studied and a Tauc plot was prepared to determine the bandgap of MoS2, ZnO, and MBZ, and also, the FL spectra were studied for the quenching effect for detection of Hg
$^{{2}+}$
. A facile drop casting technique was used to develop a highly sensitive Hg
$^{{2}+}$
detection scheme. The operating principle of the MBZ device for Hg
$^{{2}+}$
detection depends on the current/conductance variation with various concentrations of Hg
$^{{2}+}$
. Moreover, an electronic detection scheme based on MBZ was developed for ultralow-level sensing Hg
$^{{2}+}$
with limit of detection (LOD) 1 pM (
${S}/\!{N} >3$
).