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Flower‐Like Nickel Phosphide Microballs Assembled by Nanoplates with Exposed High‐Energy (0 0 1) Facets: Efficient Electrocatalyst for the Hydrogen Evolution Reaction
Author(s) -
Wang Honglei,
Xie Ying,
Cao Hongshuai,
Li Yanchao,
Li Lin,
Xu Zhikun,
Wang Xiuwen,
Xiong Ni,
Pan Kai
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201701647
Subject(s) - phosphide , tafel equation , overpotential , electrocatalyst , catalysis , nickel , water splitting , materials science , chemical engineering , nanotechnology , chemistry , electrochemistry , metallurgy , electrode , organic chemistry , photocatalysis , engineering
The fabrication of low‐cost and earth‐abundant electrocatalysts for the hydrogen evolution reaction (HER) over a broad pH range is attractive. In this work, a facile precursor route is developed to synthesize flower‐like nickel phosphide microballs with a diameter of approximately 12 μm. With a controlled phosphorization temperature, flower‐like nickel phosphide microballs with different crystalline structures (Ni 5 P 4 and Ni 2 P) were obtained easily. Flower‐like Ni 5 P 4 microballs possessed two advantageous features for enhanced HER: fast vectorial electron transfer path along the building block nanoplates and enhanced inherent catalytic activity of each active site for high‐energy (0 0 1) facets. The flower‐like Ni 5 P 4 microballs electrocatalyst thus displayed excellent activity for the HER with a low overpotential ( η ) of 35.4 mV to reach current densities of 10 mA cm −2 and a small Tafel slope of 48 mV dec −1 in acid solution. In addition, it showed excellent activity in 1 m KOH with η =47 mV at 10 mA cm −2 . DFT studies indicated that the free energy of hydrogen adsorbed on the Ni site of Ni 5 P 4 was 0.152 eV, which is smaller than that of the Ni site of Ni 2 P (0.182 eV). Therefore, flower‐like Ni 5 P 4 microballs exhibited better HER activity than Ni 2 P, which is consistent with our HER data. This hierarchical structure with exposed high‐energy (0 0 1) facets paves the way to design and synthesize low‐cost, high‐performance catalysts for the HER.