Copper-induced synthesis of palladium/copper popcorn nanoparticles as sensors for differential pulse voltammetric determination of dopamine

Abstract

Popcorn nanoparticles (pop-NPs) consisting of a Pd/Cu alloy were synthesized using a seed-mediated growth method. The Cu and Pd atoms were co-deposited on a cubic Pd seed to reduce the energy of fault stacking. The same synthesis method with a reduced volume of the Cu(II) salt leads to Pd/Cu alloy nanoparticles with branches (br-NPs). Large Pd nanocubes (Pd NCs) were prepared via epitaxial deposition and using tetrachloropalladate (PdCl₄²⁻) only. The high-resolution TEM analysis results show the pop-NPs and br-NPs to be single crystals with $\left(0\overline{2}1\right)$ and $\left(02\overline{2}\right)$ planes, respectively. The results of X-ray photoelectron spectroscopy and cyclic voltammetry measurements corroborated that Pd is enriched on both surfaces. The materials were placed on a glassy carbon electrode to obtain a differential pulse voltammetric sensor for dopamine (DA). The electrochemical sensitivities are (a) 1.55 μA μM⁻¹ cm⁻² for the Pd/Cu pop-NP sensor in its linear range (15–300 μM), (b) 1.17 μA μM⁻¹ cm⁻² for the br-NP sensor in the linear range (15–200 μM), and (c) 0.97 μA μM⁻¹ cm⁻² for the Pd NC sensor in its linear range (15–100 μM). The best working potentials are near 0.10 V (vs. SCE) for all three sensors. The pop-NP-based sensor performs particularly well due to it selectivity over ascorbic and uric acid.