Effects of Pd nanocube size of Pd nanocube-graphene hybrid on hydrogen sensing properties

Palladium (Pd) nanocubes-loaded graphene were synthesized by a simple chemical method for hydrogen sensing. Pd nanocubes of 25, 40, 55, 70 and 85 nm sizes were synthesized in colloidal state by a chemical route in two-steps (seed-mediated growth) and then, simply reduced into graphene flakes by hydrazine in a simple one-step process. The hydrogen-sensing and electrocatalyst properties of the new Pd nanocube-graphene hybrid were investigated in detail. The resistivity-type sensor that used the Pd cube-graphene hybrid had a detectable range from 10,000 to 10 ppm with good response and linearity at room temperature. Our experiment showed that the Pd cube-graphene hybrid with bigger Pd nanocubes not only showed better response to H2 gas molecules but also maintained its excellent H2 sensing properties even with increases in working temperature. The effects of Pd nanocube size on the H2 sensing performance of the Pd cube-graphene hybrid was explained by both spillover mechanism and influence of Pd size on hybrid state of two materials.