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Electrochemical Characterization of Gold-Nanostructured Platinum Substrates and Application to Determination of Hg(II) at Trace Levels

[ Vol. 15 , Issue. 1 ]

Author(s):

Pham Thi Hai Yen, Vu Hai Dang, Pham Hong Phong and Vu Thi Thu Ha*   Pages 3 - 10 ( 8 )

Abstract:


Objectives: To develop gold nanostructure (AuNDs) on Pt substrate for the detection of Hg(II) in environment by DPASV technique. Its structure was characterized by SEM and electrochemical performance was evaluated. The fabricated electrodes were used to measure Hg(II) samples in a concentration range from 2 to 100 ppb.

Method: Gold nanoparticles (AuNPs) and AuNDs were electrochemically deposited on platinum substrates by applying potential of +0.50V for AuNPs deposition and galvanostatic of -50mA for AuNDs/Pt in a solution 20mM HAuCl4, 10mM KI, 5mM NH4Cl and 0.5M H2SO4.The electrochemical behaviors of AuNPs/Pt and AuNDs/Pt were examined using CV in 5mM K3[Fe(CN)6]/0.1M PBS solution, pH = 7 and the detection of Hg(II) was performed by DPASV.

Results: The SEM images show that largest surface area was obtained at 120s depositing time. Effective surface areas (ESA) of AuNPs and AuNDs are about 1.39 and 5.19 times higher than electrode geometric area. Calibration curves achieved with R2= 0.9978; 0.9975; 0.9973 and LOD= 0.55; 0.105 and 0.042 ppb for Au disk, AuNPs/Pt and AuNDs/Pt respectively. Reproducibility with ten measurements of 10, 40 and 80 ppb of Hg(II), RSD (%) were 3.5, 2.8 and 1.5 respectively. No significant effect on Hg(II) signals was found except Cu(II) with 100 times higher than CHg(II). Comparison with AAS, data difference between the two techniques is acceptable, at only 4.34%.

Conclusion: LOD for Hg(II) detection by AuNDs/Pt achieved 0.042 ppb with a linear range of 2.0–100 ppb. Combining with a laboratory constructed galvano-potentiostat, it can be used in on-site measurement.

Keywords:

Electrochemical sensor, gold nanoparticles, gold nanodendrites, mercury detection, trace levels.

Affiliation:

Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Vietnam; University of Science and Technology of Hanoi (USTH), Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi



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