Defect-rich Fe-doped Ni2P microflower with phosphorus vacancies as a high-performance electrocatalyst for oxygen evolution reaction

The development of efficient, durable, and low-cost non-noble metal-based electrocatalysts for the oxygen evolution reaction (OER) is crucial for the extensive application of water electrolysis, which is a sustainable technique for ultrapure hydrogen production. Herein, defect-rich Fe-doped Ni2P microflowers with abundant phosphorus vacancies (Fe-Ni2P-VP) are synthesized via a simple hydrothermal process, thermal phosphidation, and subsequent partial reduction method. The simultaneous introduction of Fe dopants and phosphorus vacancies in Fe-Ni2P-VP effectively reduce the charge transfer resistance and moderately adjust the electronic structure. Consequently, the Fe-Ni2P-VP exhibits high OER activity with a small overpotential of 289 mV to reach a current density of 10 mA cm−2, turnover frequency of 2.531 s−1 at a potential of 1.6 V vs. RHE, and low Tafel slope of 54.7 mV dec−1. Moreover, the long-term durability of Fe-Ni2P-VP is confirmed through chronopotentiometry tests over 100 h in an alkaline solution. This study provides new insights into the synthesis of noble-metal-free electrocatalysts for future energy storage and conversion systems.