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Electrochemical sensors provide an excellent platform for in situ water pollutant detection. Graphene-based electrochemical sensors have been effective in the analysis of different genres of pollutants. However, the complex, chemically intensive steps of graphene fabrication and its modification pose challenges to the large-scale application of these sensors. Laser-induced graphene (LIG) is a promising technology with a simple, rapid, chemical-free, mask-free, and scalable solution to produce graphene-based electrochemical sensors. Among a diverse array of water pollutants, 4-nitrophenol (4-NP) is a critical pollutant owing to its acute toxicity and adverse health effects on humans and other living organisms. It is known to have carcinogenic, mutagenic, and teratogenic effects on aquatic life, plants, and human beings at very low concentrations. This work demonstrated a simple nonreceptor-based electrochemical sensor for 4-NP detection by laser-induced graphene (LIG) printed on polyimide (PI) films. The laser irradiation of polymeric films results in 3D porous graphene structure formation, which increases the electron transfer rate as well as the electrochemically active surface area. The LIG sensor was fabricated by optimizing laser settings and characterized by SEM, TEM, XRD, Raman spectroscopy, XPS, TGA, and EDS analysis. Using linear sweep voltammetry, the LIG sensors demonstrated linear behavior in two concentration ranges from 0.15 to 1 μM and 2.5 to 100 μM with a detection limit of 95 nM. A higher sensitivity was observed for the lower concentration range, which could be attributed to increased electrochemical sites for 4-NP in the porous LIG. The sensor showed good selectivity toward 4-NP in the presence of its isomers and other phenolic compounds. Furthermore, it showed good selectivity in sewage samples spiked with different 4-NP concentrations. The enhanced sensitivity of LIG toward 4-NP at a lower concentration range could pave the way for high-performance sensors using LIG for environmental and other applications.

No abstract

Electrochemical sensors provide an excellent alternative for the in-situ detection of pollutants in water. 4-Nitrophenol is a critical pollutant owing to its acute toxicity and adverse health effects on humans and other living organisms. It is known to have carcinogenic, mutagenic, and teratogenic effects on aquatic life plants and human beings at very low concentrations. In this work, a facile electrochemical sensor for 4-Nitrophenol detection is proposed by laser-induced graphene (LIG) printed on polyethersulfone (PES) and polyimide (PI) films respectively. The laser irradiation of polymeric films results in 3D porous graphene structure formation that increases electron transfer rate as well as the electrochemically active surface area (EASA). This fabrication approach by laser-scribing provides a simple, fast, chemical-free, mask-free, and scalable solution to produce graphene-based electrochemical sensors for 4-Nitrophenol. Cyclic voltammetry is used as the electrochemical technique for the highly sensitive detection of 4-Nitrophenol. PES-based LIG sensors exhibit a higher sensitivity of 3793 µAmM-1cm-2 as compared to that of PI-based LIG sensors with a sensitivity of 3025 µAmM-1cm-2.