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Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance
Published on: April 27, 2018
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Controllable structure reconstruction of nickel-iron compounds toward highly efficient oxygen evolution
Azhar Mahmood1, Qiangmin Yu, Yuting Luo
1Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) and Tsinghua Shenzhen International Graduate School (TSIGS), Tsinghua University, Shenzhen 518055, PR China. bilu.liu@sz.tsinghua.edu.cn.
Nanoscale
|May 11, 2020
Summary
Researchers synthesized nickel-iron (Ni-Fe) compounds for the oxygen evolution reaction (OER). The 2D Ni0.8Fe0.2-LDH nanosheets showed the highest OER activity due to optimized Ni oxidation states and structure.
Area of Science:
- Electrochemistry
- Materials Science
- Catalysis
Background:
- Nickel-iron (Ni-Fe) compounds are promising electrocatalysts for the oxygen evolution reaction (OER).
- Understanding the active phase structure and composition is crucial for optimizing Ni-Fe catalyst performance.
- Rational design requires precise control over composition and active site exposure.
Purpose of the Study:
- To synthesize and characterize various Ni-Fe compounds with controlled Fe incorporation.
- To investigate the structure-activity relationship of these compounds in the OER.
- To identify the key factors governing the enhanced catalytic performance of Ni-Fe materials.
Main Methods:
- Synthesis of Ni-Fe layered double hydroxides (LDHs) and NiFe2O4 with varying Fe concentrations.
- Preparation of control samples: β-Ni(OH)2 and α-Fe2O3.
- Electrochemical characterization of OER activity, including overpotential and Tafel slope measurements.
- In situ spectroscopic analyses (Raman, XAS, XPS) to probe electronic structure and oxidation states.
Main Results:
- Two-dimensional Ni0.8Fe0.2-LDH nanosheets exhibited superior OER activity, achieving a low overpotential of 235 mV at 10 mA cm-2 and a Tafel slope of 41 mV dec-1.
- The optimized Ni-Fe compound demonstrated excellent stability for over 24 hours.
- In situ spectroscopy revealed that the enhanced activity is attributed to the increased oxidation state of Ni from Ni2+ to Ni3+.
Conclusions:
- The composition and structure of Ni-Fe compounds significantly influence the oxidizing ability of Ni and thus their OER catalytic performance.
- A strong correlation exists between the nanostructure, Ni oxidation state, and OER activity, highlighting the importance of well-engineered Ni-site electronics.
- This study provides a guideline for designing high-performance Ni-Fe electrocatalysts and emphasizes the critical role of compositional and structural tuning.
