Markarian Marie Zabel, El Harakeh Maysaa, Halaoui Lara I
Chemistry Department, The American University of Beirut, Beirut 110236, Lebanon.
J Phys Chem B. 2005 Jun 16;109(23):11616-21. doi: 10.1021/jp044267m.
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.
通过在阳离子聚电解质聚（二烯丙基二甲基氯化铵）中逐层组装聚丙烯酸酯包覆的铂纳米颗粒（直径d = 2.5±0.6 nm）的纳米结构电极，在聚丙烯酸酯包覆的铂纳米颗粒的微晶位点上报道了原子氢电吸附。在1 M硫酸中的循环伏安法揭示了分别归因于在改性纳米微晶的（100）和（110）位点吸附的强吸附氢状态和弱吸附氢状态。解析氢吸附状态表明，羧酸根基团的表面封端不会不可逆地阻断改性铂纳米颗粒表面的氢吸附位点。吸附峰电流随着层数增加至16个双层而增加，表明通过颗粒间电荷跳跃进行纳米颗粒充电的可行性以及纳米颗粒/聚电解质多层膜厚度内吸附状态的可及性。尽管在1 M硫酸中的循环伏安图中氢吸附相似，但相对于多晶块状铂表面，在纳米微晶铂-聚电解质多层膜上测量到吸附电位的负移。这种电位偏移归因于铂纳米颗粒表面改性和聚电解质环境导致的还原氢吸附的动力学限制。
