title: Characterization of hydrogen responsive nanoporous palladium films synthesized via a spontaneous galvanic displacement reaction.
abstract: A model is presented regarding the mechanistic properties associated  with the interaction of hydrogen with nanoporous palladium (np-Pd) films prepared using a spontaneous galvanic displacement reaction (SGDR), which involves PdCl(2) reduction by atomic Ag. Characterization of these films shows both chemical and morphological factors, which influence the performance characteristics of np-Pd microcantilever (MC) nanomechanical sensing devices. Raman spectroscopy, uniquely complemented with MC response profiles, is used to explore the chemical influence of palladium oxide (PdO). These combined techniques support a reaction mechanism that provides for rapid response to H(2) and recovery in the presence of O(2). Post-SGDR processing via reduction of PdCl(2)(s) in a H(2) environment results in a segregated nanoparticle three-dimensional matrix dispersed in a silver layer. The porous nature of the reduced material is shown by high resolution scanning electron microscopy. Extended grain boundaries, typical of these materials, result in a greater surface area conducive to fast sorption/desorption of hydrogen, encouraged by the presence of PdO. X-ray diffraction and inductively coupled plasma-optical emission spectroscopy are employed to study changes in morphology and chemistry occurring in these nanoporous films under different processing conditions. The unique nature of chemical/morphological effects, as demonstrated by the above characterization methods, provides evidence in support of observed nanomechanical response/recovery profiles offering insight for catalysis, H(2) storage and improved sensing applications.
authors.affiliation: Department of Chemistry/Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Patton
authors.forename: N V
authors.initials: NV
authors.lastname: Lavrik
authors.forename: D C
authors.initials: DC
authors.lastname: Joy
authors.forename: S R
authors.initials: SR
authors.lastname: Hunter
authors.forename: P G
authors.initials: PG
authors.lastname: Datskos
authors.forename: D B
authors.initials: DB
authors.lastname: Smith
authors.forename: M J
authors.initials: MJ
authors.lastname: Sepaniak
mesh_terms: D055664:Electrochemical Techniques; D006859:Hydrogen / Q000032:analysis* / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods*; D010100:Oxygen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D012834:Silver / Q000737:chemistry; D013499:Surface Properties
chemical_list: D012834:Silver; D010165:Palladium; D006859:Hydrogen; C048320:palladium oxide; C008756:palladium chloride; D010100:Oxygen