Vertical Fe(OH)3/Ni9S8 nanoarrays electrodeposited on stainless steel as binder-free electrocatalyst for highly efficient and stable oxygen evolution reaction

The widely acknowledged water splitting catalysis as an alternative to fossil fuel combustion becomes unproductive due to the involved sluggish oxygen evolution reaction (OER) kinetics. Therefore, it is extremely urgent and significant to develop an inexpensive OER catalyst with fast reaction dynamics, high efficiency and long-term stability. To address such issues, herein, for the first time, we present a novel vertical Fe(OH)3/Ni9S8 nanoarrays electrocatalyst that can rapidly fabricated on etched stainless steel (ESS) via a facile and swift electrodeposition process. The Fe(OH)3/Ni9S8/ESS exhibits excellent OER performance with ultra-low overpotential of 206 mV at 10 mA cm−2 (far better than RuO2/ESS) and shows outstanding long-term stability. The terrific OER performance can be attributed to the integration of well-designed nanoarchitecture, and the coupling effect between Fe(OH)3 and Ni9S8. The direct nanoarrays electrodeposition on highly conductive ESS substrate not only facilitate the rapid electron transfer for enhanced performance, but also improve the mechanical properties to ensure long-term stability. Additionally, the well-designed porous nanoarray guarantees abundant catalytically active sites exposure, facilitate the electrolyte penetration and promote the O2 bubble release. Interestingly, the systematically fabricated Fe(OH)3 outer layer can prevent the direct contact of Ni9S8 layer with alkaline electrolyte to avoid surface oxidation during catalysis. This work provides a systematic strategy to rationally design and facilely fabricate low-cost electrocatalysts with outstanding OER performance.