Theoretical Insights into Enhanced Electrocatalytic Arsenic Oxidation on Au‐Decorated Pt Surfaces in Neutral Medium

This study explores the electrocatalytic oxidation of arsenite on Au nanoparticle-decorated Pt surfaces in a neutral medium. DFT calculations showed stronger arsenite adsorption on Au-Pt (E _ads = − 2.045 eV) than on pure Au (−0.611 eV) or Pt (−0.769 eV), indicating enhanced catalytic activity. SEM, PXRD, EIS, and CV analyses confirmed synergistic Au-Pt interactions, enabling efficient As(III) oxidation via a diffusion-controlled first-order process. Tafel analysis revealed improved charge transfer (slope = 277 mVdec⁻¹), while activation polarization demonstrated lower overpotential (|η _a| = 1.28 V vs. Pt's 1.56 V), validating the Au-Pt system's superior efficiency for arsenic sensing.

Abstract

In this study, we present a comprehensive theoretical and experimental investigation of the electrocatalytic oxidation of arsenite on Au immobilized Pt surfaces in a neutral medium. Theoratically, density functional theory (DFT) calculations revealed that thePt-Au bimetallic system exhibits superior adsorption energy (E _ads = −2.045 eV) compared to bare Au (−0.611 eV) and Pt (−0.769 eV) surfaces, indicating enhanced arsenite affinity and catalytic activity. Experimental characterizations, including SEM, PXRD, EIS, and CV, confirmed the formation of noble catalytic sites on Au and synergistic effects between Au and Pt, facilitating efficient As(III) oxidation. The reaction followed first-order kinetics with a diffusion-controlled mechanism, as evidenced by a diffusion coefficient of 3.20 × 10⁻⁷ cm²s⁻¹. Tafel analysis further elucidated the reaction kinetics, revealing a reduced Tafel slope (277 mVdec⁻¹) for the Pt-Au electrode, indicative of improved charge transfer. Activation polarization analysis demonstrated lower overpotential (|η _a| = 1.28 V) for thePt-Au system compared to bare Pt (1.56 V), highlighting its enhanced catalytic efficiency and internal synergy after Au deposition. The findings align with theoretical predictions, underscoring the potential of Pt-Au bimetallic surfaces for arsenic sensing.