Three distinct hydrogen sensing responses of palladium line patterns generated by femtosecond laser direct writing

Application of a palladium nanostructure in hydrogen detection is a focus of current research due to its high sensitivity. In this paper, palladium nanometre films are fabricated using femtosecond laser decomposition of palladium acetate films. Their hydrogen sensing characteristics are studied as a function of hydrogen concentration and morphologies of palladium films. As palladium film morphologies vary from continuous to partially continuous and then to discontinuous, the corresponding hydrogen response changes from normal to pulse-like and then to switch-like. Their response characteristics are determined by the different combined effects of the formation of high-resistance palladium hydrogen and the corresponding narrowing of nanogaps between palladium nanoparticles.