Boosting selective H2 sensing of ZnO derived from ZIF-8 by rGO functionalization

Abstract

Hydrogen (H₂) 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 H₂ 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 H₂ sensing. This composite demonstrated dramatic H₂ selectivity against other flammable gases, particularly ethanol, which was improved by deoxygenation to reduce the surface oxygen functional groups. This sample showed excellent H₂ sensing with a high response of ∼18 to 200 ppm H₂, and a response/recovery time of 50/7 s at 400 °C. Even at a certain low temperature of 200 °C, the composite showed evident response to H₂. 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.