Wavelength Dependent Graphene Oxide-Based Optical Microfiber Sensor for Ammonia Gas.

Saad Hayatu Girei,Mohd Hanif Yaacob,Mohammed Majeed Alkhabet,Hong Ngee Lim,Yasmin Mustapha Kamil,Mohd Adzir Mahdi

doi:10.3390/s21020556

Saad Hayatu Girei, Mohd Hanif Yaacob + Show 4 more

Open Access

https://doi.org/10.3390/s21020556

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Abstract

Ammonia detection in ambient air is critical, given its implication on the environment and human health. In this work, an optical fiber tapered to a 20 µm diameter and coated with graphene oxide was developed for absorbance response monitoring of ammonia at visible (500–700 nm) and near-infrared wavelength regions (700–900 nm). The morphology, surface characteristics, and chemical composition of the graphene oxide samples were confirmed by a field emission scanning electron microscope, an atomic force microscope, X-ray diffraction, and an energy dispersion X-ray. The sensing performance of the graphene oxide-coated optical microfiber sensor towards ammonia at room temperature revealed better absorbance response at the near-infrared wavelength region compared to the visible region. The sensitivity, response and recovery times at the near-infrared wavelength region were 61.78 AU/%, 385 s, and 288 s, respectively. The sensitivity, response and recovery times at the visible wavelength region were 26.99 AU/%, 497 s, and 192 s, respectively. The selectivity of the sensor towards ammonia was affirmed with no response towards other gases.

Highlights

Ammonia (NH3 ) has emerged as an important building block in the manufacturing of many products we use daily, including plastics, textiles, dyes, and household cleaning solutions
We have studied the absorbance characteristics of graphene oxide (GO) when introduced to different concentrations of NH3 gas (0.04–0.5%) and discovered that the sensitivity of the sensor has a significant dependency on the operational wavelength region
From the FESEM image of GO-coated tapered optical microfiber as shown in Figure 3a, it can be observed that the GO nanomaterial adhered well to the surface of the optical fiber

Summary

Introduction

Ammonia (NH3 ) has emerged as an important building block in the manufacturing of many products we use daily, including plastics, textiles, dyes, and household cleaning solutions. There has been increasing interest in optical fiber sensors due to their unparalleled advantages over their electrical equivalents, such as simplicity of operation, real-time monitoring, immunity of various sources of interference, e.g., radiofrequency activity, electromagnetic interference, and explosive environment [5,6]. These characteristics make them cost-effective, flexible, and inert for gas sensing applications. The experimental results showed that the prepared sensor has a high sensitivity towards NH3 gas

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