(395f) Flame Aerosol Synthesis of Palladium-Decorated Crumpled Reduced Graphene Oxide Nanocomposites for Hydrogen Detection at Room Temperature

Hydrogen (H₂), a green energy source, is highly flammable with a lower explosive limit of just 4% in air. Its leakage during production, transportation, and storage can result in disastrous consequences. Therefore, development of accurate, rapid, and stable H₂ sensors that work in air at room temperature is crucial. In this presentation, we will describe a novel three-dimensional palladium (Pd)-decorated crumpled reduced graphene oxide ball (Pd-CGB) nanocomposite for H₂ detection in air at room temperature. Pd-CGB nanocomposites were synthesized using a flame-driven high temperature reducing jet (HTRJ) process. In this process, a hydrogen-rich flame passes through a converging-diverging nozzle. An aqueous precursor solution containing graphene oxide and palladium nitrate is injected at the throat section of the nozzle and is atomized by the high velocity gas stream. The resulting droplets evaporate, graphene oxide sheets crumple, and the palladium precursor decomposes, initiating nucleation of palladium nanoparticles on crumpled graphene oxide in a reducing environment containing excess H₂. After the reaction zone, nanocomposites are cooled immediately to prevent further growth and coalescence of the Pd nanoparticles. Hydrogen sensors produced by simple drop-casting of these nanocomposites onto electrodes performed well over a wide range of H₂ concentrations (0.01-2%) with response (resistance change) value, response time, and recovery time of 14.8%, 73 s, and 126 s, respectively, at 2% H₂. Compared with other reports on Pd-graphene sensors, the present study shows superior response/recovery time. The HTRJ process enables the single-step, continuous production of Pd- and other metal-decorated graphene nanocomposites with great potential for creating various gas sensors by simple drop-casting onto low-cost electrodes.