Selective detection of dopamine at the AACVD synthesized palladium nanoparticles and understanding the sensing mechanism through electrochemical and computational study

In this work, a selective dopamine (DA) sensor has been constructed based on thin film (TF) palladium nanoparticles (PdNPs) fabricated over indium tin oxide (ITO) (TFPdNP_ITO) by aerosol assisted chemical vapor deposition (AACVD) method. The TFPdNP_ITO electrodes were characterized with SEM, XRD, EDX, XPS, cyclic voltammetry (CV), tafel plot analysis, and electrochemical impedance spectroscopy (EIS). We performed geometry optimization of metallic planes, and Monte Carlo Search (MCS) computational simulations of DA, and interfering species to understand the effects of PdNPs on the selective DA detection at the atomic level. The total energy, and bind energy calculations from geometry optimizations showed that DA had the most negative energy value, and was most likely to interact with the TF of PdNPs. The adsorption locator module also predicted similar results through MCSs. A possible reaction mechanism for the DA oxidation at the TFPdNP_ITO was predicted based on the experimental and computational findings. The amperometry analysis showed linear range, sensitivity, and LOD of 1.77 μM – 543 μM, 0.009 μA/μM, and 0.13 ± 0.06 μM, respectively. The TFPdNP_ITO sensor was further tested for stability, and reproducibility. Commercial dopamine hydrochloride injection (DAHI) was used for the real sample analysis using both DPV, and amperometry techniques.