Unique Ni Crystalline Core/Ni Phosphide Amorphous Shell Heterostructured Electrocatalyst for Hydrazine Oxidation Reaction of Fuel Cells

Jin Zhang; Xinyue Cao; Min Guo; Haining Wang; Martin Saunders; Yan Xiang; San Ping Jiang; Shanfu Lu

doi:10.1021/acsami.9b00878

Unique Ni Crystalline Core/Ni Phosphide Amorphous Shell Heterostructured Electrocatalyst for Hydrazine Oxidation Reaction of Fuel Cells

ACS Appl Mater Interfaces. 2019 May 29;11(21):19048-19055. doi: 10.1021/acsami.9b00878. Epub 2019 May 16.

Authors

Jin Zhang¹, Xinyue Cao¹, Min Guo¹, Haining Wang¹, Martin Saunders², Yan Xiang¹, San Ping Jiang³, Shanfu Lu¹

Affiliations

¹ Beijing Key Laboratory of Bio-inspired Materials and Devices & School of Space and Environment , Beihang University , Beijing 100191 , China.
² Center for Microscopy, Characterization and Analysis (CMCA) , The University of Western Australia , Perth WA6009 , Australia.
³ Fuels and Energy Technology Institute & Western Australia School of Mines: Mineral, Energy and Chemical Engineering , Curtin University , Perth WA6102 , Australia.

PMID: 31062967
DOI: 10.1021/acsami.9b00878

Abstract

It is highly attractive but challenging to develop transition-metal electrocatalysts for direct hydrazine fuel cells (DHzFCs). In this work, a nickel crystalline core@nickel phosphide amorphous shell heterostructured electrocatalyst supported by active carbon (Ni@NiP/C) is developed. Ni@NiP/C with a P/Ni molar ratio of 3:100, Ni@NiP_3.0/C, exhibits outstanding catalytic activity for the hydrazine oxidation reaction (HzOR) in alkaline solution, achieving a much better catalytic activity (2675.1 A g_Ni^-1@0.25 V vs RHE) and high stability, as compared to Ni nanoparticles supported on carbon (Ni/C) and Pt/C catalysts. The results indicate that formation of the NiP amorphous shell effectively inhibits the passivation of the Ni core active sites and enhances the adsorption of hydrazine on Ni by improving the adsorption energy, leading to high electrochemical activity and stability of the Ni@NiP_3.0/C catalysts for HzOR. The density functional theory calculation confirms the structural and electrocatalytic effect of the core-shell heterostructure on the stability and activity of Ni active sites for HzOR. The unique crystalline core/amorphous shell-structured Ni@NiP/C demonstrates promising potential as an effective electrocatalyst for DHzFCs.

Keywords: Ni phosphide; Ni@NiP/C core−shell heterostructured electrocatalysts; amorphous structure; direct hydrazine fuel cells; hydrazine oxidation reaction.