Fe-Decorated 2D AlN Monolayers as Sensor Materials for Octane and Toluene Molecules: A First-Principles Study

This study examines the use of 2D AlN- and Fe-decorated 2D AlN monolayers as sensing materials for octane and toluene molecules. Fe decoration on the nitrogen (N) sites on the AlN surface leads to a decrease in the band gap. The K-edge XANES study indicates that Fe decoration is in a 2+ oxidation state over the AlN monolayer, with a characteristic peak similar to that of wustite. Toluene molecules exhibit chemisorption over Fe-decorated AlN, whereas octane undergoes physisorption, as confirmed by AIM analysis. Octane and toluene showed the highest sensitivity (approximately 99%) over Fe-decorated AlN owing to the influence of Fe atoms at the Fermi level. The current voltage characteristics were simulated via DFT-NEGF, in which a significant current change occurred due to the adsorption of biomarkers in the Fe-decorated monolayer even at a low bias voltage (~0.1 V). The recovery rate is rapid in pristine 2D AlN, in contrast to the long recovery rate observed in the Fe-decorated AlN monolayer owing to the high adsorption energy. Based on the present investigation, Fe-decorated 2D AlN monolayers demonstrate strong potential for the detection of toluene and octane biomarkers, establishing them as promising candidates for biosensing applications.