Tweaking Nickel with Minimal Silver in a Heterogeneous Alloy of Decahedral Geometry to Deliver Platinum‐like Hydrogen Evolution Activity. (9th January 2020)

• Record Type: Journal Article
• Authors: Majee, Rahul; Kumar, Arun; Das, Tisita; Chakraborty, Sudip; Bhattacharyya, Sayan
• Is Part Of: Angewandte Chemie. Volume 132:Number 7(2020)
• Page Start: 2903
• Page End: 2911
• Publication Date: 2020-01-09
• Subjects: Bimetallische Katalysatoren -- Elementaranalyse -- Heterogene Katalyse -- Tenside -- Wasserstoffentwicklungsreaktion; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201913704
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Five‐fold intertwined Ag x Ni1− x ( x =0.01–0.25) heterogeneous alloy nanocrystal (NC) catalysts, prepared through unique reagent combinations, are presented. With only ca. 5 at % Ag (AgNi‐5), Pt‐like activity has been achieved at pH 14. To reach a current density of 10 mA cm −2 the extremely stable AgNi‐5 requires an overpotential of 24.0±1.2 mV as compared to 20.1±0.8 mV for 20 % Pt/C, both with equal catalyst loading of 1.32 mg cm −2 . The turnover frequency (TOF) is as high as 2.1 H2 s −1 at 50 mV (vs. RHE). Site‐specific elemental analyses show the Ag:Ni 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. Abstract : Fünffache verflochtene Nanokristall‐Katalysatoren aus der heterogenen Legierung Ag x Ni1− x ( x =0.01–0.25) werden vorgestellt. Mit nur 5 at % Ag (AgNi‐5) wird eine Pt‐artige Aktivität bei pH 14 erreicht. Eine Stromdichte von 10 mA cm −2 benötigt eine Überspannung von 24.0±1.2 mV (20.1±0.8 mV für 20 % Pt/C, beides mit 1.32 mg cm −2 Katalysatorbeladung). Die Turnoverfrequenz beträgt bis zu 2.1 H2 s −1 bei 50 mV (vs. RHE).