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Palladium/Stannic Oxide Interfacial Chemistry Promotes Hydrogen Oxidation Reactions in Alkaline Medium
Author(s) -
Ipadeola Adewale K.,
Mwonga Patrick V.,
Ray Sekar C.,
Maphanga Rapela R.,
Ozoemena Kenneth I.
Publication year - 2020
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202000952
Subject(s) - exchange current density , chemistry , tafel equation , catalysis , electrocatalyst , palladium , thermogravimetric analysis , electrochemistry , x ray photoelectron spectroscopy , inorganic chemistry , oxide , anode , chemical engineering , electrode , organic chemistry , engineering
A nanostructured Pd/SnO 2 on metal‐organic‐framework‐derived carbon (Pd/SnO 2 /MOFDC) electrocatalyst and its monometallic catalyst (Pd/MOFDC) have been synthesized by microwave‐assisted strategies and investigated for the alkaline hydrogen oxidation reaction (HOR). Physical properties of the electrocatalysts are examined using X‐ray diffraction, thermogravimetric analysis, X‐ray photoelectron spectroscopy, Brunauer‐Emmett‐Teller analysis, transmission electron microscopy, and density functional theory. This study reveals that the Pd/SnO 2 /MOFDC possesses superior alkaline HOR activities (in terms of kinetic current, heterogeneous rate constant, diffusivity, exchange current density, and the mass activity) compared to those of the Pd/MOFDC and that are comparable to commercial Pt/C. The improved alkaline HOR activity on Pd/SnO 2 /MOFDC is attributed to the facile interfacial electrochemical processes arising from the multifunctional properties of SnO 2 with the thin Sn film: i) weakening of Pd‐H ads , confirmed by DFT simulation, and ii) oxophilic (thin Sn film) and spill‐over (SnO 2 ) effects that quickly transfer OH − ions to the desorbed H ads for facile reaction in the Volmer rate‐determining step (RDS). Tafel slope ( b a =52–102 mV dec −1 ) and activation energy ( E A ) values suggest the predominance of the Heyrovsky‐Volmer process. In addition to the improved HOR activity of Pd/SnO 2 /MOFDC, it also exhibits better stability than Pd/MOFDC. The good performance of Pd/SnO 2 /MOFDC toward the alkaline HOR promises potential development of low‐cost anode materials for alkaline membrane fuel cells.