UV-activated gold decorated rGO/ZnO heterostructured nanocomposite sensor for efficient room temperature H₂ detection

Extended surface area in addition to higher conductivity and abundant free electrons/holes generation has been key players for any efficient sensor design. Therefore, contribution from graphene as highest conductive material and plasmonics from gold (Au) were expected to facilitate efficient zinc oxides (ZnO) nanostructures-based Hydrogen gas detection. We have presented herewith a facile route to synthesize ZnO nanosheets from elongated nanoblocks of the same in presence of reduced graphene oxide (rGO) under laser ablation environment. Au decorated such rGO/ZnO heterostructured nanosheets were found to be highly selective and sensitive to H₂ detection under ultraviolet radiation at room temperature (RT). A detailed investigation was carried out to confirm topographic evolution through high resolution scanning electron microscopy. Optical band gap and infrared absorption of as-synthesized specimens at different stages were investigated further in addition to structural confirmation using X-ray diffraction analysis. Raman spectroscopy, a complementary technique was utilized to investigate the specimens at different stages too. SEM-aided elemental analysis inferred that gold nanoparticles were homogeneously distributed over the rGO/ZnO heterostructure. A custom-made setup designed at our disposal were utilized to understand the selectivity and sensitivity of as-fabricated heterostructure for H₂ detection. The H₂ gas sensing properties of Au nanoparticles decorated rGO/ZnO heterostructure were investigated at RT under UV irradiation and compared with those observed using pristine ZnO nanostructure at high working temperature. A plausible mechanism was illustrated with reference to well-known ‘spell-over’ scenario usually observed in plasmonic sensors.