Adsorption of Atomic Hydrogen at a Nanostructured Electrode of Polyacrylate-Capped Pt Nanoparticles in Polyelectrolyte

Abstract

Atomic hydrogen electrosorption is reported at crystallite sites of polyacrylate-capped Pt nanoparticles (d = 2.5 +/- 0.6 nm), by assembling nanostructured electrodes of polyacrylate-Pt nanocrystallites layer-by-layer in a cationic polyelectrolyte, poly(diallyldimethylammonium chloride). Cyclic voltammetry in 1 M H2SO4 revealed a strongly adsorbed hydrogen state and a weakly adsorbed hydrogen state assigned to adsorption at (100) and (110) sites of the modified nanocrystallites, respectively. Resolving hydrogen adsorption states signifies that surface capping by the carboxylate groups is not irreversibly blocking hydrogen adsorption sites at the modified Pt nanoparticle surface. Adsorption peak currents increased with increasing the number of layers up to 16 bilayers, indicating the feasibility of nanoparticle charging via interparticle charge hopping and the accessibility of adsorption states within the thickness of the nanoparticle/polyelectrolyte multilayers. Despite similarity in hydrogen adsorption in the cyclic voltammorgrams in 1 M H2SO4, negative shifts in adsorption potentials were measured at the nanocrystallite Pt-polyelectrolyte multilayers relative to a polycrystalline bulk Pt surface. This potential shift is attributed to a kinetic limitation in the reductive hydrogen adsorption as a result of the Pt nanoparticle surface modification and the polyelectrolyte environment.

Metallic and bimetallic Cu/Pt species supported on carbon surfaces by means of substituted phenyl groups

“…It is noteworthy that the H adsorption/desorption waves were clearly observed despite the presence of organic groups at the electrode surface. Similarly, these redox waves were recently found in the case of layer-by-layer assembly of Pt nanoparticles in polydiallydimethylammonium chloride [48].…”

Synthesis and characterization of polyhedral Pt nanoparticles: Their catalytic property, surface attachment, self-aggregation and assembly

“…Therefore, PVP has played an important role to stabilize their morphology and size of these Pt nanoparticles. In addition, PVP was possibly adsorbed on the surface of {1 0 0} facets and on various surfaces of Pt nanoparticles were easily be removed by organic solvents [27,28]. Despite the fact that Pt nanoparticles were put on a b 10 nm c 50 nm 50 nm carbon-coated copper grids, they still have their interfacial interactions to form large Pt nanoparticles around 20 nm and up to 60 nm in our research through an oriented attachment and directed aggregation that was introduced in the formation of Pd nanostructures [42].…”

“…The measurements were cycled until the stable voltammograms were achieved. The electrochemical surface areas (ECA) were estimated by considering the area under the curve in the hydrogen desorption region of the forward scan and using 0.21 mC/cm 2 [28], for the monolayer of hydrogen adsorbed on a Pt surface.…”

“…The electrochemical surface area (ECA) from the hydrogen desorption region was calculated as follows: ECA = Q H / (0.21 Â L Pt ), where 0.21 served as the conversion factor (in mC/ cm 2 ). The L Pt parameter was the catalyst loading on the glassy carbon surface (in mg/cm 2 ) [28,57]. The ECA was estimated $10.53 m 2 /g, such one high value for an unsupported configuration.…”

Dissociation kinetics at polyacrylic latex-coated electrodes

“…Negatively charged molecules such as hexacyanoferrate cannot be simply taken up to PAA [5]. PAA can immobilize cytochrome c [13] and big particles such as multiwalled carbon nanotubes [14], gold nanoparticles [15], CdS nanoparticles with cupper ion [16], and platinum nanocrystals [17]. It makes copolymers with polyaniline [18,19] and has immobilized flavin adenin dinucleotide for detection of glucose [20].…”