Chemically Exfoliated Titanium Carbide MXene for Highly Sensitive Electrochemical Sensors for Detection of 4-Nitrophenols in Drinking Water

Abstract

Soil and water contamination by numerous pollutants has been increasingly posing threats to food, water, agriculture, and human health. Using novel nanoscale materials to develop rapid electrochemical sensors is very promising due to the discovery of a number of new two-dimensional (2D) electronic materials. Of particular importance is 2D transition-metal carbide MXene that has been shown to possess transformative properties pertaining to its physical, chemical, and environmental characteristics, leading to their potential sensor applications. Designing electrochemical sensors using MXene has the potential to pave the way for monitoring environmental pollutants. Here, a stacked layer of chemically exfoliated MXene (Ti 3 C 2 T x ) was demonstrated as an electrochemical sensor for detection of 4-nitrophenol (4-NP) with high sensitivity and a low limit of detection. Successful selective exfoliation of the MAX (Ti 3 AlC 2 ) phase of the material by chemical etching without oxidation is shown to be the key to achieving higher sensitivity and a lower detection limit. In the optimal conditions, the proposed MXene sensor electrodes were capable of detecting 4-NP in a broad concentration range from 500 nM to 100 μM with a good linear sensing range (regression fit, R = 0.995). The higher sensitivity and notable limit of detection reached about 16.35 μA μM −1 cm −2 and 42 nM/L, respectively, with good reproducibility and repeatability. The real-time application of the proposed MXene sensor electrodes was confirmed by testing in tap water samples with excellent recoveries of 95−99%.

MXene‐Based Flexible Sensors: Materials, Preparation, and Applications

“…Reproduced with permission. [ 234 ] Copyright 2022, Elsevier. g) Gas sensor for food spoilage detection.…”

“…Wang et al. [ 234 ] reported an electrochemical sensor based on Ti 3 C 2 T x , capable of monitoring the water pollutant nitrobenzol (Figure 15f). All of these research studies illustrate the usefulness of MXene‐based flexible sensors in environmental sensing, particularly gas sensors and electrochemical sensors.…”

“…Aromatic compounds containing nitrogen groups are widely used in the petroleum industry, pesticides, dyes, and so on, and if discharged untreated, will have toxic effects on the growth and metabolism of organisms, including humans, and these compounds include 4-nitrophenols, [233] p-nitrophenols, [234] and so on. Wang et al [234] reported an electrochemical sensor based on Ti 3 C 2 T x , capable of monitoring the water pollutant nitrobenzol (Figure 15f). All of these research studies illustrate the usefulness of MXene-based flexible sensors in environmental sensing, particularly gas sensors and electrochemical sensors.…”

“…f) Schematic diagram of the detection process of the electrochemical sensor. Reproduced with permission [234]. Copyright 2022, Elsevier.…”

Recent trends in nanostructured carbon-based electrochemical sensors for the detection and remediation of persistent toxic substances in real-time analysis

“…Krishnamoorthy et al [109] reported the use of a stack sheet of chemically highly porous MXene (Ti 3 C 2 Tx) as an electrochemical sensor for the specificity and minimal LOD sensitivity of 4-nitrophenol (4-NP). The solution to obtaining additional sensibility and minimal LOD was demonstrated to be the effective selective exfoliating of the MAX (Ti 3 AlC 2 ) stage of the substance by chemical etching excluding oxidation.…”