Boosting selective H-2 sensing of ZnO derived from ZIF-8 by rGO functionalization

Hydrogen (H-2) sensors based on metal oxide semiconductors (MOSs) have attracted considerable attention for safety concerns of traditional industries and energy storing devices. ZnO has been widely studied as an n-type MOS in H-2 sensing due to the excellent stability, mobile conductive carriers, and wide bandgap. However, the poor selectivity and high working temperature limit its practical applications. Herein, we designed a heterostructure based on ZIF-8-derived ZnO by rGO functionalization to boost the selective H-2 sensing. This composite demonstrated dramatic H-2 selectivity against other flammable gases, particularly ethanol, which was improved by deoxygenation to reduce the surface oxygen functional groups. This sample showed excellent H-2 sensing with a high response of similar to 18 to 200 ppm H-2, and a response/recovery time of 50/7 s at 400 degrees C. Even at a certain low temperature of 200 degrees C, the composite showed evident response to H-2. The excellent gas sensing behavior could be attributed to the heterojunctions and enhanced electron mobility. Regulation of the surface oxygen-containing functional groups opens up a promising approach to adjust the gas sensing selectivity of MOS-based materials.