An investigation of Fe incorporation on the activity and stability of homogeneous (FexNi1-x)2P solid solutions as electrocatalysts for alkaline hydrogen evolution. (20th January 2019)

• Record Type: Journal Article
• Authors: Zhang, Bowei; Zhang, Jingjing; Tang, Xiaohui; Lui, Yu Hui; Hu, Shan
• Is Part Of: Electrochimica acta. Volume 294(2019)
• Page Start: 297
• Page End: 303
• Publication Date: 2019-01-20
• Subjects: Fe-Ni phosphide -- Lattice substitution -- Adsorption competition -- Hydrogen generation -- Stability; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.10.107
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Ni2 P has been intensively investigated for hydrogen evolution reaction (HER) in recent years since the HER activity of Ni2 P (001) is theoretically superior to Pt. Most of these works have focused on acid system as Ni2 P is unstable in alkaline media. However, alkaline water splitting is more practical for industry due to the lack of suitable acidic oxygen evolution catalyst. Thus, providing an efficient alkaline HER catalyst by enhancing the stability and activity of Ni2 P is needed. Herein, we have grown mesoporous (Fex Ni1-x )2 P nanosheets on Ni foam (NF) as HER catalyst with activities being related to Fe/Ni ratio. FeNiP/NF with Fe/Ni ratio of 5/5 and high-density exposure of (001) surface shows much better stability and HER activity in alkaline than Ni2 P. Our experimental results reveal that the homogeneous lattice substitution of Fe modified the electronic structure of Ni2 P, enhanced the intrinsic activity and the number of active sites. Density functional theory calculation reveals that the Fe incorporation improves the HER activity of the highly exposed FeNiP (001) surface by reducing the energy barriers of HER reactants (H and H2 O) adsorption compared with Ni2 P. This work provides an effective pathway for the future development of HER catalyst in alkaline conditions by introducing hetero-atom into the host lattice. Graphical abstract: Highlights: Homogeneous Fe-doped Ni2 P nanoarrays with tunable Fe/Ni ratio have been synthesized. Both HER stability and activity in alkaline are enhanced by lattice substitution of Fe. Mechanism was studied from the experimental and theoretical aspects.