Hydrogen Sensing at Room Temperature Using Flame-synthesized Palladium-decorated Crumpled Reduced Graphene Oxide Nanocomposites.

We present a unique three-dimensional palladium (Pd)-decorated crumpled reduced graphene oxide ball (Pd-CGB) nanocomposite for hydrogen (H-2) detection in air at room temperature. Pd-CGB nanocomposites were synthesized using a rapid continuous flame aerosol technique. Graphene oxide reduction and metal decoration occurred simultaneously in a high-temperature reducing jet (HTRJ) process to produce Pd nanoparticles that were below 5 nm in average size and uniformly dispersed in the crumpled graphene structure. The sensors made from these nanocomposites were sensitive over a wide range of H-2 concentrations (0.0025-2%) with response value, response time, and recovery time of 14.8%, 73 s, and 126 s, respectively, at 2% H-2. Moreover, they were sensitive to H-2 in both dry and humid conditions. The sensors were stable and recoverable after 20 cycles at 2% H-2 with no degradation associated with volume expansion of Pd. Unlike two-step methods for fabricating Pd-decorated graphene sensors, the HTRJ process enables single-step formation of Pd- and other metal-decorated graphene nanocomposites with great potential for creating various gas sensors by simple drop-casting onto low-cost electrodes.