Tweaking Nickel with Minimal Silver in a Heterogeneous Alloy of Decahedral Geometry to Deliver Platinum‐like Hydrogen Evolution Activity. Issue 7 (9th January 2020)

• Record Type: Journal Article
• Authors: Majee, Rahul; Kumar, Arun; Das, Tisita; Chakraborty, Sudip; Bhattacharyya, Sayan
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 7(2020)
• Page Start: 2881
• Page End: 2889
• Publication Date: 2020-01-09
• Subjects: bimetallic catalysts -- elemental analyses -- heterogeneous catalysis -- hydrogen evolution reaction -- surfactants; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201913704
• Languages: English
• ISSNs: 1433-7851

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 : Five‐fold intertwined Ag x Ni1− x ( x =0.01–0.25) heterogeneous alloy nanocrystal catalysts are presented. With only 5 at % Ag (AgNi‐5), Pt‐like activity is 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 (20.1±0.8 mV for 20 % Pt/C, both with a catalyst loading of 1.32 mg cm −2 ). The turnover frequency is up to 2.1 H2 s −1 at 50 mV (vs. RHE).