Colorimetric determination and recycling of gold(III) ions using label-free plasmonic H0.3MoO3 nanoparticles

A low-cost and environment-friendly sensor was developed for visual determination of gold ions (Au3+) by using label-free hydrogen doped molybdenum oxide (H0.3MoO3) nanoparticles as ratio probes. According to the characterization results of transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectra, Au3+ is easily reduced to red Au nanoparticles (AuNPs) by blue H0.3MoO3 nanoparticles. The color change of the solution depends on the concentration of Au3+, which makes it possible to detect Au3+ visually. Under optimal experimental conditions of pH 4.6, H0.3MoO3 nanoparticles concentration of 0.075 mg center dot mL(-1), and reaction time of 7 min, the sensor offers a satisfactory determination range from 0.5 to 70 mu M and a good determination limit of 0.45 mu M for Au3+. The concentration of Au3+ as low as 10 mu M can be directly distinguished through the naked eye. Additionally, the colorimetric probe has also been proved applicable in environmental water samples. More importantly, the resulting AuNPs have good stability and oxidase-like activity, which may be directly used in sensing, catalysis, energy, and other fields.

Automated summary

A low-cost and environment-friendly sensor was developed using label-free hydrogen doped molybdenum oxide nanoparticles as ratio probes for visual determination of gold ions (Au3+). The reduction of Au3+ to Au nanoparticles (AuNPs) by H0.3MoO3 nanoparticles resulted in a color change of the solution, enabling visual detection of Au3+. The sensor showed satisfactory detection range and limit for Au3+ and can be applied in environmental water samples. Additionally, the resulting AuNPs exhibited stability and oxidase-like activity, making them useful in various fields.