Composite 2D Nanointerfaces for Electrochemical Biosensing: An Experimental and Theoretical Study

In this study, composite two-dimensional (2D) materials consisting of graphene (Gr) and tungsten disulfide (WS2) were coalesced with gold nanoparticles (AuNPs) through a self-assembly process to boost the conductivity of the resulting graphene-tungsten disulfide-gold nanoparticles (Gr-WS2-AuNPs) nanointerface structure. Structural and morphological characterization of the nanohybrid structure reveals crystalline thin flakelike agglomerates. Electrochemical characterization reveals an excellent electron transfer process for all the modified electrodes at the interface. The Gr/WS2/AuNPs/HRP/GCE modified bioelectrode exhibited a rapid electrobiocatalytic response in detecting H2O2 and a linear response from 0.40 to 23 mM, while 11.07 μA/mM/cm2 is the sensitivity value. This shows that the fabricated Gr/WS2/AuNPs/HRP interface structure is an excellent material for future developments in electrochemical biosensing and bioelectronics applications. The interactions, geometry, and energetic and electronic properties of H2O2 adsorption onto Gr/WS2/Au using the density functional theory (DFT) method have also been investigated along with the Grimme's DFT-D3 dispersion method. Different adsorption modes of the H2O2 molecule onto the Gr/WS2/Au surface were considered. In almost all the cases, the adsorption was found to be energetically favorable and chemisorbed, with energies ranging from -2.198 to -3.782 eV. It was found that the W 5d, S 3p, and Au 6s orbitals play a vital role in the adsorption process. The H2O2 adsorption on Gr/WS2/Au remarkably decreases its work function, thereby increasing the field electron emission from the H2O2 molecule to Gr/WS2/Au.