Retraction of "Nanogold and Multiwalled Carbon Nanotubes Composited Electrode for Phosphate Detection by Measuring the Oxygen Activity of Manganese Oxides".

Abstract

On the basis of electrochemical signal differences caused by the different oxygen activities of phosphate-promoted and pure MnO2, an electrochemical method for the rapid detection and quantification of phosphate was proposed in the study. A glassy carbon electrode (GCE) composed of nanogold (AuNPs) and thiol-modified multi-walled carbon nanotubes (SH-MWCNTs) were developed for phosphate detection. The SH-MWCNTs/AuNPs/GCE loaded with two types of MnO2 was directly applied as a working electrode in a three-electrode system. It presented good analytical performance with a wide linear range of 10-6-10-1 mol/L and a favorable sensitivity with a detection limit of 5 × 10-7 mol/L, which was below the detection threshold. The nanostructure of the MWCNT layer not only had a large surface area and excellent adsorption capacity but also accelerated the electron transfer in the oxygen electrochemical reaction due to its superior conductivity. Interference studies were carried out, and the results revealed the ideal selectivity of the sensor in distinguishing phosphate and interfering species. Recovery percentages of 89% ± 5.1% and 140.3% ± 6.9% were achieved in poor water and artificial wastewater, respectively. Results indicated the feasibility of using the proposed sensor to detect phosphate under specific conditions.