S-vacancy-rich NiFe-S nanosheets based on a fully electrochemical strategy for large-scale and quasi-industrial OER catalysts

The oxygen evolution reaction (OER) is regarded as a critical component in the water splitting system. Creating vacancies, increasing active surface area , and optimizing electronic structure would improve electrocatalytic performance. Herein, a facile electrochemical reduction method is used to generate sulfur vacancies in nickel iron sulfide (NiFe-S) with a large geometry area of 15 × 16 cm 2 , which is synthesized using an electrodeposition process assisted with the ion exchange (IOE) method. The X-ray absorption spectroscopies (XAS) are applied for atomic-level structural analysis, verifying that electrochemical desulfurization generates abundant S vacancies . The NiFe-S with abundant sulfur vacancies (NiFe-S-V s ) exhibits a low overpotential (252 mV at 100 mA cm −2 ), and long stability for 260 h at 500 mA cm −2 . More importantly, the NiFe-S-V s catalyst also delivers a small overpotential (235 mV at 1000 mA cm −2 ) and high alkaline tolerance (140 h at 500 mA cm −2 ) in 6 M KOH at 60 °C), implying a potentially significant industrial application prospect. Finally, theory calculation further illustrates the high performance of as-prepared vacancies-rich catalyst. • Rich vacancies were created by electrochemical reduction . • Sulfur vacancy can modulate the electronic structure from XAS and DFT results. • Scaled-up sulfides with more than 15 × 16 cm 2 were prepared. • NiFe-S-0.6/NF only needs 235 mV to reach 1000 mA cm −2 in industry conditions. • NiFe-S-0.6/NF can maintain over 140 h in industry-like conditions.