Tweaking Nickel with Minimal Silver in a Heterogeneous Alloy of Decahedral Geometry to Deliver Platinum-like Hydrogen Evolution Activity.
Angew Chem Int Ed Engl
; 59(7): 2881-2889, 2020 Feb 10.
Article
en En
| MEDLINE
| ID: mdl-31825552
ABSTRACT
Five-fold intertwined Agx Ni1-x (x=0.01-0.25) heterogeneous alloy nanocrystal (NC) catalysts, prepared through unique reagent combinations, are presented. With only ca. 5â
at % Ag (AgNi-5), Pt-like activity has been achieved at pHâ
14. To reach a current density of 10â
mA cm-2 the extremely stable AgNi-5 requires an overpotential of 24.0±1.2â
mV as compared to 20.1±0.8â
mV for 20 % Pt/C, both with equal catalyst loading of 1.32â
mg cm-2 . The turnover frequency (TOF) is as high as 2.1 H2 â
s-1 at 50â
mV (vs. RHE). Site-specific elemental analyses show the AgNi compositional variation, where the apex and edges of the decahedra are Ag-rich, thereby exposing Ni onto the faces to achieve maximum charge transport for an exceptional pH universal HER activity. DFT calculations elucidate the relative H-atom adsorption capability of the Ni centers as a function of their proximity to Ag atom.
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2020
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Article