Ionic Liquids with Various Constituent Ions To Optimize Non-Enzymatic Electrochemical Detection Properties of Graphene Electrodes

Abstract

Palladium (Pd) nanoparticles, ionic liquids (ILs), or both are integrated with graphene sheets to serve as an electrochemical sensor for detecting various bio-species. Ascorbic acid (AA), uric acid (UA), and dopamine (DA) are used as the model analytes. To assess the effects of the constituent ions of ILs on sensing properties, various ILs, namely, EMI–SCN, EMI–DCA, BMP–DCA, BMI–PF6, EMI–NTF2, and BMP–NTF2, are investigated. The results demonstrate that the graphene/IL electrode shows superior detection sensitivity compared to those of the graphene/Pd and graphene/Pd/IL electrodes. Interestingly, the IL anions are found to play a crucial role in sensing performance. Angle-resolved X-ray photoelectron spectroscopy reveals that graphene can create an aligned cation/anion orientation in the adsorbed IL film, with the anions preferentially occupying the topmost surface, thus dominating the interaction with analytes. The graphene/EMI–SCN electrode shows the highest sensitivity among the electrodes, 1.49 μA μM–1 cm–2, and a detection limit of 0.11 μM toward DA. Even with large excesses of AA and UA, the concentration of DA can be effectively detected.

Supercritical Fluid-Assisted Fabrication of Pd Nanoparticles/Graphene Using a Choline Chloride–Oxalic Acid Deep Eutectic Solvent for Enhancing the Electrochemical Oxidation of Glycerol

“…Some examples showing the range of Pd nanomaterials prepared in scCO 2 have appeared. 18 − 23 To prepare versatile Pd nanomaterials, the size of the Pd nanoparticles (NPs) is usually reduced, and they are supported on various carbon materials. 24 , 25 Graphene (GR) with excellent electrical conductivity and a high surface area represents an excellent support material and, when used, it improves the electronic properties of nanomaterials through the strong interactions between the graphene and the Pd nanoparticles.…”

“…Supercritical carbon dioxide (scCO 2 ) is the most commonly used solvent because it is environmentally friendly, nonflammable, chemically inert, and relatively inexpensive. Moreover, many organometallic precursors with long alkyl chains that cannot typically be utilized in supercritical water (scH 2 O) or supercritical ethanol (scEtOH) can be solubilized in scCO 2 because the scCO 2 has a similar density to the liquid carbon dioxide, which retains equal solvation power. ,− Pd nanomaterials have proven to be excellent catalysts in many reactions, including organic coupling reactions, fuel cells, hydrogen storage, and sensing. Owing to the wide range of applications of this element, many techniques for the synthesis of Pd nanostructures have been developed, including deposition using a supercritical fluid.…”

“…Owing to the wide range of applications of this element, many techniques for the synthesis of Pd nanostructures have been developed, including deposition using a supercritical fluid. Some examples showing the range of Pd nanomaterials prepared in scCO 2 have appeared. − To prepare versatile Pd nanomaterials, the size of the Pd nanoparticles (NPs) is usually reduced, and they are supported on various carbon materials. , Graphene (GR) with excellent electrical conductivity and a high surface area represents an excellent support material and, when used, it improves the electronic properties of nanomaterials through the strong interactions between the graphene and the Pd nanoparticles. , Therefore, Pd NPs/GR composites are potential materials for use in electrochemical sensors and as catalysts. Polyols such as ethylene glycol and glycerol have several advantages over the traditional fuels (methanol, ethanol, and formic acid) used for energy conversion in fuel cells.…”

Lignosulfonate in situ-modified reduced graphene oxide biosensors for the electrochemical detection of dopamine

“…17)), metal nanoparticles (AuNPs 18 and AgNPs 19 ), conductive polymers (PPy 20,21 and PANI 22 ) and ionic liquids. 23 Although these organic and metal-based modifiers can be employed to achieve sensitive detection, their significant threat to the environment and high consumption of chemical resources limit their wide application. Hence, it is essential to urgently develop greener modifiers instead of the expensive, nondegradable and toxic modifiers.…”