Hierarchical nanohybrids of B- and N-codoped graphene/mesoporous NiO nanodisks: an exciting new material for selective sensing of H2S at near ambient temperature

Abstract

Hydrogen sulfide (H₂S) is an extremely toxic gas and comes under the classification of chemical asphyxiants. To date, numerous metal oxide-based gas sensors have been developed for the detection and quantification of H₂S. However, high sensing temperature, low sensitivity, humidity dependence, and very high response/recovery time severely limit their practical applications. Herein, we prepared hierarchical mesoporous nickel oxide (NiO) nanodisks and boron–nitrogen co-doped reduced graphene oxide (rGO)-NiO (NiO_BNG) nanodisk composites for H₂S sensing. The as-prepared materials were investigated by several techniques to determine their morphologies, crystal structures, phase purity, and compositions. The sensing response of the NiO_BNG sensor to 100 ppm H₂S at 150 °C was ∼82, and the detection limit of the sensor was ∼24 ppb. The NiO_BNG sensor showed 2- and 3-fold stronger response compared to pristine rGO incorporated NiO and bare NiO nanodisk sensors. The enhanced sensing performance of the NiO_BNG sensor is attributed to the presence of several catalytically active sites provided by boron and nitrogen doped rGO in the NiO_BNG nanocomposite. The ease of the synthesis procedure, excellent sensitivity, selectivity, rapid response, high stability, and ambient temperature operation make for intriguing, promising practical applications of our NiO_BNG sensor, especially in explosive environments and medical diagnosis.