New electrochemical sensor based on Ni-doped V2O5 nanoplates modified glassy carbon electrode for selective determination of dopamine at nanomolar level

•Ni-doped V2O5 nanoparticles have been prepared by thermal decomposition method.•Ni-doped V2O5 exhibits highly sensitive and selective dopamine sensing property.•Possible dopamine sensing mechanism has been proposed.•Ni-V2O5 sensor shows good linear range, reproducibility, repeatability and stability.

Ni-doped (0, 2, 5 and 7 wt%)V2O5 nanoparticles were prepared by thermal decomposition method. The as-prepared nanoparticles are characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, UV–Vis absorption spectroscopy, scanning electron microscopy (SEM) and high resolution-transmission electron microscopy (HR-TEM). The results indicated that the Ni2+ ions are well doped within V2O5 lattices. Compared with pure V2O5, Ni-doped V2O5 (Ni-V2O5) nanoparticles exhibit enhanced dopamine (DA) sensing property. Particularly, 7%Ni-V2O5 nanoplates modified glassy carbon electrode (7%Ni-V2O5/GCE) showed a good response to the DA concentration in the range of 6.6–96.4 μM with sensitivity of 132 nA μM−1. The obtained limit of detection (LOD) is 28 nM (S/N = 3). A possible mechanism related to the electrochemical oxidation of DA was proposed. Further, the proposed method was successfully utilized to determine DA in dopamine hydrochloride solution (11–13 μM) and reasonable results were obtained. The results showed that the 7%Ni-V2O5/GCE exhibits an excellent electrocatalytic activity, good sensitivity, reproducibility, repeatability and long-term stability.

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