Gallium Nitride-Based Potentiometric Anion Sensor

Abstract

The gallium nitride (GaN) semiconductor is used as the sensing element for the development of a potentiometric anion sensor. The anion recognition mechanism is based on the selective interaction of anions in solution with the epitaxial Ga-face polarity GaN (0001) wurtzite crystal film grown on sapphire. The native GaN crystal is used for the development of an ion blocked sensor. The potential is based on the Volta potential, generated at the semiconductor/solution interface and within the Helmholtz layer, due to specifically adsorbed anions. The selectivity of the sensor is based on the direct interaction of the anionic ligand with the outer electron-defective gallium atoms; thus, it is not dependent on the lipophilicity of the adsorbed charged species. The chemical resistivity of the GaN crystal provides sensors with excellent lifetime, signal stability, and reproducibility.

Evaluation of GaN and In0.2Ga0.8N Semiconductors as Potentiometric Anion Selective Electrodes

“…51.9 AE 3.7 mV/decade and are generally consistent with those reported by Chaniotakis [13,14]. The largest difference occurs for KSCN (À 51.9 AE 3.7 mV/decade in our study versus À 69.5 mV/decade in Chaniotakis [13,14] ).…”

“…The linear regions of the GaN electrode in this research are generally of similar magnitude or wider than those reported by Chaniotakis [13,14] with the same electrolyte solutions.…”

“…The parameters of the calibration plots obtained with the GaN and In 0.2 Ga 0.8 N semiconductor electrodes are summarized in Table 2. For comparison, the table also contains the parameters of the calibration plots presented by Chaniotakis [13,14], which were extracted from their published experimental data.…”

Electrochemical Sensors

“…28 Here, anion recognition is based on adsorption processes on the gallium face of the (0001) GaN crystal in analogy to early work on CdS based membranes, but unfortunately the reported ion selectivities were not impressive.…”

Gallium (III)-acetate speciation studies under physiological conditions.

“…Redox chemistry is, therefore, not possible for Ga(III) in biological mediums (2). The coordination chemistry of gallium (III) ions has been largely studied in the last decades (3)(4)(5)(6)(7)(8)(9) where many ligands with oxygen and/or nitrogen donor atoms (such as carboxylate, phosphonate, phenolate, hydroxamate and amine groups) were used as chelating agents.…”