H2 In Situ Inducing Strategy on Pt Surface Segregation Over Low Pt Doped PtNi5 Nanoalloy with Superhigh Alkaline HER Activity

By Cong Zhang, Xin Liang, Ruinian Xu, Chengna Dai, Bin Wu, Gangqiang Yu, Biaohua Chen, Xiaolei Wang, Ning Liu. Advanced Functional Materials, 2020

138 citations recorded by the source corpus.

Surface segregation constitutes an efficient approach to enhance the alkaline hydrogen evolution reaction (HER) activity of bimetallic PtxNiy nanoalloys. Herein, a new strategy is proposed by utilizing the small gas molecule of H2 as the structure directing agent (SDA) to in situ induce Pt surface segregations over a series of PtNi5‐n samples with extremely low Pt doping (Pt/Ni = 0.2). Impressively, the sample of PtNi5‐0.3 synthesized under 0.3 MPa H2 delivers an extremely low overpotential of 26.8 mV (−10 mA cm−2) and Tafel slope of 19.2 mV dec−1, which is superior to most of the previously reported PtxNiy electrocatalysts. This is substantially related to the strong H2 in situ inducing effect to generate Pt‐rich@Ni‐rich core‐shell nanostructure of PtNi5‐0.3 with an ultrahigh Pt surface content of 46%. The specific mechanistic effects of H2 during the PtNi5‐n synthesis process are well illustrated based on the combined experimental and theoretical studies. The density functional theory mechanism simulations further unravel that the evolved active site of PtNi5‐n can efficiently reduce the reaction Gibbs free energies; especially for the scenario of PtNi5‐0.3, the downward‐shifted d band center of the Pt active site significantly reduces the PtH bond strength, eventually resulting in the lowest absolute value of ΔGH.

Subfields: Electrical and Electronic Engineering, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/3a5f0e31730e3e10945de957f636a52ceda9b6d2