Palladium/Stannic Oxide Interfacial Chemistry Promotes Hydrogen Oxidation Reactions in Alkaline Medium. Issue 22 (30th September 2020)

• Record Type: Journal Article
• Authors: Ipadeola, Adewale K.; Mwonga, Patrick V.; Ray, Sekar C.; Maphanga, Rapela R.; Ozoemena, Kenneth I.
• Is Part Of: ChemElectroChem. Volume 7:Issue 22(2020)
• Page Start: 4562
• Page End: 4571
• Publication Date: 2020-09-30
• Subjects: hydrogen oxidation reaction (HOR) -- palladium-stannic oxide (Pd/SnO2) catalyst -- electrochemistry -- interfacial chemistry -- density functional theory (DFT); Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.202000952
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: A nanostructured Pd/SnO2 on metal‐organic‐framework‐derived carbon (Pd/SnO2 /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/SnO2 /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/SnO2 /MOFDC is attributed to the facile interfacial electrochemical processes arising from the multifunctional properties of SnO2 with the thin Sn film: i) weakening of Pd‐Hads, confirmed by DFT simulation, and ii) oxophilic (thin Sn film) and spill‐over (SnO2 ) effects that quickly transfer OH − ions to the desorbed Hads 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/SnO2 /MOFDC, it also exhibits better stability than Pd/MOFDC. The good performance of Pd/SnO2 /MOFDC toward the alkaline HOR promises potential development of low‐cost anode materials for alkaline membrane fuel cells. Abstract : Fuel for thought : The interfacial chemistry of a palladium‐stannic oxide electrocatalyst is harnessed for improved alkaline hydrogen oxidation reaction (HOR) kinetics and stability, which is proven by both experimental and theoretical investigations. This work provides an insight into the design and synthesis of reduced‐cost, efficient and effective electrocatalysts for alkaline membrane fuel cells.