Flake-like reduced graphene oxide embedded in ZnO hollow spheres: Toward high-response and rapid-recovery N2H4 Sensors

rGO/ZnO- x ( x  = 1, 2, 3, 4) composites were successfully synthesized via a two-step co-precipitation method for effective hydrazine (N 2 H 4 ) detection, achieved by embedding reduced graphene oxide (rGO) flakes into ZnO hollow spheres. A systematic study was carried out on the effect of rGO incorporation on the gas sensing performance of the composites, and the enhanced mechanism was deeply discussed. The results indicated that the rGO/ZnO-3 sample exhibited optimum gas-sensing performance, achieving a high response value of 81 and a short response/recovery times (21 s/95 s) to 50 N 2 H 4 at 180℃, along with a low detection limit of 0.1 ppm, excellent reproducibility and long-term stability. The enhanced sensing performance of rGO/ZnO-3 sample can be attributed to the synergistic effect of structural advantages (3D porous networks for rapid gas diffusion) and electronic effects (heterojunction-driven charge transfer), achieving dual optimization of gas adsorption kinetics and signal transduction efficiency. This study presents an effective strategy for developing high-performance N 2 H 4 sensors while offering new insights into the modification of metal oxide-based sensing materials.