Investigating the Effects of Surface Adsorbates on Gold and Palladium Deposition on Carbon

Abstract Surface functional groups have a strong influence on the deposition and final state of nanoparticles adsorbed to surface, role discussed by Professor Spencer in his work. This tribute explores formation hydroxyls, thiosulfates, sulfites sulfur atoms carbon (HOPG) surfaces their effect gold palladium from aqueous solutions. Hydroxyls formed ammonium hydroxide treatment identical behaviour those acid treatment, adsorption Au 3+ solutions gives 0 initially, with at higher concentrations these surfaces. In contrast, is hindered presence hydroxyls there no indication any reduction metallic state. Ammonium thiosulfate adsorbs dissociatively HOPG if surface pre-activated hydroxyls. At low thiosulfate, sulfite are equimolar whereas high some degree molecular adsorption, evidence XP spectra for an ion 2p peak 282.9 eV attributed undissociated ion. Both stable neutral but desorbs when treated acidified (~ pH ≤ 6). These two also 373 K begin desorb 473 K. Exposure weak chloroauric solution causes desorption species binding energy 84.6 eV; we cannot determine present data whether this due Au(I) or very small Au(0). Graphic