4.6 Article

Increased Sensitivity and Selectivity for As(III) Detection at the Au(111) Surface: Single Crystals and Ultraflat Thin Films Comparison

Journal

JOURNAL OF PHYSICAL CHEMISTRY C
Volume 126, Issue 48, Pages 20343-20353

Publisher

AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.2c05541

Keywords

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Funding

  1. National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP) [DGE-1418062]
  2. University of New Mexico Center for Water and the Environment, (NSF CREST grant) [1345169, 1914490]
  3. Center for Micro-Engineered Materials (NSF MRI Award) [DMR-1828731]
  4. Fulbright U.S. Scholar Senior Research Award
  5. Division Of Human Resource Development
  6. Direct For Education and Human Resources [1914490] Funding Source: National Science Foundation

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The use of highly oriented Au(111) single crystal and thin film surfaces can improve the detection of arsenic (As) in water by reducing the variance in analyte electrode surface adsorption and desorption energies. An ultraflat Au(111) thin film exhibits a similar response to a bulk Au(111) single crystal and can be used to detect trace concentrations of As in water.
Electrochemical stripping voltammetry electroanal-ysis sensitivity and selectivity are oftentimes limited by wide variance in analyte electrode surface adsorption and desorption energies. The use of highly oriented Au(111) single crystal and thin film surfaces is shown to decrease this variance and improve detection for arsenic (As) in water. Cyclic voltammetry and linear stripping voltammetry (LSV) analysis on Au oriented and polyoriented electrode surfaces demonstrated that As deposition and oxidation is a complex surface-structure-dependent process. An electrochemical quartz microbalance indicated that As is deposited in multiple layers when in high concentrations and does not permanently reorganize the Au surface after stripping. LSV analysis of As(III) on the Au(111), Au(110), Au(100), and Au polyoriented single crystal, Au(Poly), model electrode surfaces showed that Au(111) had the highest peak to background ratio and narrowest peak width for As oxidative stripping. Furthermore, an ultraflat Au(111) thin film, Au(UTF), was then compared to the Au(111) and Au(Poly) single crystals and showed a bulk Au(111) single crystal-like response. The Au(UTF) was then used to perform a calibration curve to detect between 2.5 and 100 mu g L-1 As(III) and resulted in a theoretical limit of detection of 0.0065 mu g L-1 in 0.5 M H2SO4. The results from this study indicate that the Au(UTF) surface provides the sensitivity necessary for detection of trace concentrations of As in water at or below the maximum contaminant level (MCL) of 10 mu g L-1.

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