P-Doped Iron-Nickel Sulfide Nanosheet Arrays for Highly Efficient Overall Water Splitting

Caichi Liu; Dongbo Jia; Qiuyan Hao; Xuerong Zheng; Ying Li; Chengchun Tang; Hui Liu; Jun Zhang; Xueli Zheng

doi:10.1021/acsami.9b04528

P-Doped Iron-Nickel Sulfide Nanosheet Arrays for Highly Efficient Overall Water Splitting

ACS Appl Mater Interfaces. 2019 Aug 7;11(31):27667-27676. doi: 10.1021/acsami.9b04528. Epub 2019 Jul 25.

Authors

Caichi Liu¹, Dongbo Jia¹, Qiuyan Hao¹, Xuerong Zheng², Ying Li¹, Chengchun Tang^{1

3}, Hui Liu¹, Jun Zhang^{1

3}, Xueli Zheng⁴

Affiliations

¹ School of Material Science and Engineering , Hebei University of Technology , Dingzigu Road 1 , Tianjin 300130 , P. R. China.
² School of Materials Science and Engineering , Tianjin University , Tianjin Haihe Education Park , Tianjin 300072 , P. R. China.
³ Hebei Key Laboratory of Boron Nitride Micro and Nano Materials , Guangrongdao Road 29 , Tianjin 300130 , P. R. China.
⁴ Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States.

PMID: 31303002
DOI: 10.1021/acsami.9b04528

Abstract

Iron-nickel sulfide ((Ni,Fe)₃S₂) is one of the most promising bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media because of their metallic conductivity and low cost. However, the reported HER activity of (Ni,Fe)₃S₂ is still unsatisfactory. Herein, three-dimensional self-supported phosphorus-doped (Ni,Fe)₃S₂ nanosheet arrays on Ni foam (P-(Ni,Fe)₃S₂/NF) are synthesized by a simple one-step simultaneous phosphorization and sulfuration route, which exhibits dramatically enhanced HER activity as well as drives remarkable OER activity. The incorporation of P significantly optimized the hydrogen/water absorption free energy (ΔG_H*/ΔG_H₂O*), enhanced electrical conductivity, and increased electrochemical surface area. Accordingly, the optimal P-(Ni,Fe)₃S₂/NF exhibits relatively low overpotentials of 98 and 196 mV at 10 mA cm^-2 for HER and OER in 1 M KOH, respectively. Furthermore, an alkaline electrolyzer comprising the P-(Ni,Fe)₃S₂/NF electrodes needs a very low cell voltage of 1.54 V at 10 mA cm^-2 and exhibits long-term stability and outperforms most other state-of-the-art electrocatalysts. The reported electrocatalyst activation approach by anion doping can be adapted for other transition-metal chalcogenides for water electrolysis, offering great promise for future applications.

Keywords: DFT calculation; bifunctional electrocatalysts; iron nickel sulfide; phosphorus doping; water splitting.