Nitrophenols are phenolic compounds that are more acidic than phenol itself. Over the years, nitrophenol isomers have found many applications in sectors encompassing pharmaceutical, agrochemical, textiles, petroleum and even in paper industries. As a result of their excessive use, these isomers are widely distributed in the environment, particularly in surface water. 4-Nitrophenol is one specific type of nitrophenol that is highly hazardous and toxic. Generally, owing to their embryonic, mutagenic and carcinogenic nature, toxic nitrophenols in industrial waste ought to be identified and treated before discharge. As such, development of methods that could reliably detect phenols and substituted phenols in wastewater has attracted much attention in the scientific community. Electrochemical methods present an excellent approach to detect trace substrates with exemplary accuracy, sensitivity, reproducibility and stability. Unfortunately, it has been reported that bare electrodes often exhibit low sensitivity and suffer from high interference and a high overpotential. To resolve this, researchers have proposed the application of chemicals to modify the electrodes. So far, mixed results have been reported particularly regarding 4-Nitrophenol. Therefore, modified electrodes ought to be developed.
Indium silver sulfide is an attractive semiconductor with a relatively large absorption coefficient and suitable energy band gap. This material has been employed in various optoelectronics and photovoltaic areas. Unfortunately, reports regarding modified electrodes based on indium silver sulfide are rare. In this view, researchers from the College of Environmental and Chemical Engineering at Nanchang Hangkong University in China: Professor Pinghua Chen, Yangming Shi, Xueqin Li, Tao Wang, Minghui Zhou, Enzhu Tian, Wenli Wang, Professor Hualin Jiang and Professor Hongying shu proposed the use of Tremella-like Indium Silver Sulfide Modified glassy carbon electrode for the detection of 4-Nitrophenol. Their work is currently published in International Journal of Electrochemical Science.
To begin with, the researchers facilely synthesized Indium silver sulfide by co-precipitation. The researchers then proceeded to investigate the morphology and phase of tremella-like indium silver sulfide (TLISS) by scanning electron microscopy and X-ray diffraction. Lastly, the team conducted an electrochemical study using an electrochemical impedance spectroscopic technique, cyclic voltammetry and differential pulse voltammetry.
The authors reported that the as-prepared sensor detected 4-nitrophenol with high accuracy, satisfactory reproducibility and good stability in wide range of 4-nitrophenol concentrations, and the determination limit (3S/m) was as low as 1.09 μM. Remarkably, when tap and river waters were used to evaluate the practical application of the newly developed tremella-like indium silver sulfide modified glassy carbon electrode (TLISS/GCE) sensor, excellent performance was also reported.
In summary, the study reported the development of a highly sensitive electrochemical sensor for 4-nitrophenol that was based on a tremella-like indium silver sulfide modified glassy carbon electrode. Interestingly, their study is the first report regarding the 4-nitrophenol detection performance of indium silver sulfide. In a statement to Advances in Engineering, Professor Hualin Jiang highlighted that their work set precedence and will act as the foundation for the development of more highly effective 4-nitrophenol detection methods.
Pinghua Chen, Yangming Shi, Xueqin Li, Tao Wang, Minghui Zhou, Enzhu Tian, Wenli Wang, Hualin Jiang, Hongying shu. Highly Effective Detection of 4-Nitrophenol by Tremella-like Indium Silver Sulfide Modified GCE. International Journal of Electrochemical Science, volume 13 (2018) pages 6158 – 6168.