Nanoscale tunable proton/hydrogen sensing: Evidence for surface-adsorbed hydrogen atom on architectured palladium nanoparticles

By gradually decreasing the Pd concentration on Au nanoparticles from complete to incomplete surface coverage, in which well-dispersed nanoparticles are eventually obtained on the Au, we have demonstrated that the electrochemical response of hydrogen at Pd is critically dependent on the size and structure of the Pd surface. A gradual increase in the electrochemical signal attributed purely to the oxidation of adsorbed hydrogen atoms can be achieved as the Pd coverage becomes dispersed and the ratio of hydrogen atom adsorption sites compared to the absorption sites rises.