Selective uptake and sensing of nitrate in poly(3,4-ethylenedioxythiophene)

Abstract

Nitrogen (N) as a nutrient, in the form of nitrate (NO3 −), is essential for plant growth. Chemical fertilizers are used to increase crop yields, but overuse can lead to forms of environmental pollution necessitating methods to detect and monitor the level of NO3 − in-situ in agricultural soils. Herein we report for the first time the NO3 − selectivity of the inherently conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT). This selectivity occurs when PEDOT thin films are exposed to an aqueous environment containing not only NO3 −, but a mixture of other ions present in concentrations (ppm) typical of real agricultural soil. The PEDOT sensitivity to absorb NO3 − from solution is determined to be <1 ppm.

Poly(3,4 ethylenedioxythiophene)‐tosylate—Its synthesis, properties and various applications

“…In another approach, the plasma treated PVDF films were coated with the oxidant solution of iron(III) p‐toluenesulfonate on both sides, through dip coating method, and the oxidant coated PVDF film was placed into the VPP chamber and exposed to EDOT monomer vapor to achieve the PEDOT‐Tos coated PVDF flexible film for further practical application 63 . Addition of triblock polymer PEG‐PPG‐PEG to the mixture of oxidant solution with alcohols 38,62,64‐69 along with different additives such as deionized water, DMF 70 DMSO or EDTA 71 was also attempted for the synthesis of PEDOT‐Tos films through VPP. Such procedure was repeated for multiple layer synthesis of PEDOT‐Tos by sequential polymerization, until the free standing PEDOT‐Tos film was obtained 72 .…”

“…PEDOT‐Tos based materials are also used in the selection of NO 3 − not only from an aqueous environment containing NO 3 − but also from the mixture of other ions present in concentrations (ppm) in real agricultural soil 66 . Although nitrate (NO 3 − ) is a vital commodity for the growth of a plant, usage of nitrate‐based fertilizer and chemical materials can affect the environment as well as increase the health issues in human.…”

Recent advances in ion sensing with conducting polymers

“…With respect to nitrate sensing, Rudd et al [106] fabricated poly(3,4-ethylenedioxythiophene) doped with tosylate using a vapor deposition process, which was found to selectively uptake nitrate ions in the aqueous environment. The novelty of the work prescribed that, when these films start in the electrochemically reduced state, nitrate ions are selectively uptaken in the polymer matrix without any electrical methods to oxidise the poly (3,4-ethylenedioxythiophene).…”

A bird's eye view of the synthesis and practical application of conducting polymers

“…Alternatively, measurement of the electrical and/or optical properties allows for determination of the doping level within the CP. If the CP shows specific interaction or selective doping by certain ions, then ion‐sensing is possible . One general method for CP‐based ion‐sensing is via potentiometric analysis of a CP electrode exposed to the ion of interest .…”