Fabrication of dendritic nanoporous gold via a two-step amperometric approach: Application for electrochemical detection of methyl parathion in river water samples

In this work, nanoporous gold (NPG) was prepared according to three different approaches, such as (i) anodization-electrochemical reduction (A-ECR, NPG(A)), (ii) dynamic hydrogen bubble template (DHBT, NPG(B)), and (iii) the combination of both methods (NPG(A+B)). Field-emission scanning electron microscopy (FE-SEM) and cyclic voltammetry (CV) were used to investigate the structural morphology and the electrochemical behavior of the fabricated materials. The NPG(A+B) electrode showed a large amount of surface defects and/or edges, greater electrochemical surface area (2.5 cm(2)), and increased roughness factor (35.4). Such outstanding features of the NPG(A+B) platform were demonstrated by the sensitive detection of methyl parathion (MP) in river water samples. CV results indicated nearly 25-fold, 6-fold, and 2.5-fold higher sensitivity for NPG(A+B) compared to that of bare Au, NPG(A), and NPG(B), respectively. Differential pulse voltammetry (DPV) results show a linear behavior in the MP concentration range of 5-50 ng mL(-1) with a limit of detection (LOD) of 0.6 ng mL(-1) and limit of quantification (LOQ) of 2.0 ng mL(-1). Besides, the NPG(A+B) sensor also revealed excellent selectivity towards MP detection in the presence of other interfering molecules or ions, reproducibility, and repeatability.

Automated summary

In this work, nanoporous gold (NPG) was prepared using three different approaches, with the combined method showing the most surface defects, largest electrochemical surface area, and highest sensitivity for the detection of methyl parathion. The NPG(A+B) sensor demonstrated excellent selectivity, reproducibility, and repeatability for MP detection, with a linear behavior in the concentration range of 5-50 ng mL(-1) and a low limit of detection (LOD) of 0.6 ng mL(-1).