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In Situ Hydroxide Growth over Nickel-Iron Phosphide with Enhanced Overall Water Splitting Performances
Jian Hu1,2, Jiayi Yin1, Aoyuan Peng2
1College of Materials Science and Engineering, Hunan University, Changsha, 410082, China.
Small (Weinheim an Der Bergstrasse, Germany)
|July 5, 2024
Summary
This study developed novel 3D Ni-FeOH@Ni-FeP needle arrays for efficient water splitting. These advanced electrodes demonstrate exceptional oxygen evolution reaction (OER) performance and stability in alkaline electrolyzers.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Developing efficient electrocatalysts is crucial for sustainable energy technologies like water splitting.
- Nickel-iron based materials are promising for oxygen evolution reaction (OER) but often face stability and activity challenges.
Purpose of the Study:
- To fabricate and characterize novel 3D self-supported Ni-FeOH@Ni-FeP needle arrays with a core-shell heterojunction structure.
- To investigate the electrocatalytic performance of these arrays for oxygen evolution reaction (OER) and overall water splitting.
- To elucidate the underlying mechanisms contributing to the observed enhanced catalytic activity and stability.
Main Methods:
- Fabrication of 3D Ni-FeOH@Ni-FeP needle arrays via in situ hydroxide growth.
- Electrochemical testing for oxygen evolution reaction (OER) and overall water splitting.
- In situ Raman spectroscopy and density functional theory (DFT) calculations for mechanistic investigations.
Main Results:
- The Ni-FeOH@Ni-FeP electrodes exhibited outstanding OER performance with a low overpotential of 232 mV at 200 mA cm⁻² and a Tafel slope of 40 mV dec⁻¹.
- An alkaline electrolyzer using these electrodes achieved a cell voltage of 2.14 V at 1 A cm⁻² for overall water splitting.
- DFT calculations revealed improved conductivity and a favorable D-band center for Ni-FeOH@Ni-FeP, while in situ Raman confirmed the role of FeOOH intermediates in enhancing reaction dynamics and stability.
Conclusions:
- The core-shell Ni-FeOH@Ni-FeP heterojunction structure significantly enhances electrocatalytic activity and stability for OER and water splitting.
- The improved performance is attributed to enhanced intrinsic conductivity, optimized electronic structure, and the beneficial role of surface hydroxide and intermediate FeOOH species.
- This work provides a promising strategy for designing advanced electrocatalysts for efficient electrochemical energy conversion.
