Hydride phase formation in carbon supported palladium nanoparticle electrodes investigated using in situ EXAFS and XRD

Rose, Abigail; Maniguet, Stephanie; Mathew, Rebecca J.; Slater, Claire; Yao, Jun; Russell, Andrea E.

Abstract

In situ EXAFS (extended X-ray absorption fine structure), in situ XRD (X-ray diffraction) and electrochemical studies have been used to investigate the palladium hydride phases of carbon supported palladium nanoparticles as a function of applied potential. Electrochemical investigations showed an increase in the hydrogen to palladium ratio with an increasingly negative potential. The H/Pd ratio could be divided into four distinct regions, which described the palladium hydride phase present; the α-phase, a mixture of the α- and β-phases, the β-phase, and a hyperstoichiometric region. The β-hydride phase stoichiometry obtained from the electrochemical data corresponded to PdH. However, the composition obtained from the lattice expansions observed from the in situ EXAFS and XRD, 3.3% and 3.8%, correspond to compositions of PdH to PdH . The excess hydrogen and hyperstoichiometric amounts found at more negative potentials are attributed to either spillover on to the carbon support or trapping and subsequent reoxidation of H in the porous electrode structure. 0.59 0.68 2

• Journal Article Type: Article
• Publication Date: 2003
• Deposit Date: Apr 17, 2021
• Journal: Physical Chemistry Chemical Physics
• Print ISSN: 1463-9076
• Electronic ISSN: 1463-9084
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 15
• Pages: 3220-3225
• DOI: https://doi.org/10.1039/b302956e
• Public URL: https://uwe-repository.worktribe.com/output/7268281