Selective Reduction of Oxygen Functional Groups to Improve the Response Characteristics of Graphene Oxide-Based Formaldehyde Sensor Device: A First Principle Study

This paper presents a density functional theory-based first principle study to investigate the atomic-scale interactions of formaldehyde (H ₂ CO) molecules with different oxygen containing functional groups of graphene oxide to identify which particular functional group possesses better adsorption capability toward H ₂ CO molecule. The detailed study on formaldehyde adsorption has been conducted in terms of changes in structural, energetic, electronic, and transport properties of graphene oxides modeled with sp ³ hybridized hydroxyl (-OH) and epoxy (C-O-C) groups on the carbon basal plane. Our computational results suggest that the graphene oxidized with only -OH group shows the highest affinity toward formaldehyde as compared with epoxy oxidized graphene and graphene oxide containing both the functional groups. The influence of vacancy defect on improving the sensing response of graphene oxide has also been studied. The results of current-voltage (I-V) characteristics reveal that graphene oxidized with only hydroxyl group can achieve an improvement in sensitivity by almost two times and five times as compared with graphene oxide containing both the functional groups and the pristine graphene sheet, respectively. Moreover, the selectivity test for some common indoor air pollutants was also carried out and the test results suggest that H ₂ CO molecule is highly selective toward the -OH group of graphene oxide as compared with the epoxy group.