Quaternary (Fe/Ni)(P/S) mesoporous nanorods templated on stainless steel mesh lead to stable oxygen evolution reaction for over two months

Synthesis of mesoporous (Fe/Ni)(P/S) dendritic nanorods on commercial 304L stainless steel mesh (SSM) was accomplished by initial anodic oxidation and subsequent co-sulfuration/phosphorization process. The mesoporous (Fe/Ni)(P/S) dendritic nanorods were obtained as a freestanding and stable catalyst for oxygen evolution reaction (OER). The mechanism of formation of mesoprous structure with nanorods is due to in-situ removal of Cr atoms (from the hard template of SSM) while the O₂ bubbles released during OER served as dynamic bubble template (soft template). The as-prepared sample exhibited overpotentials of 173 mV at 10 mA cm⁻² and 270 mV at 100 mA cm⁻², which exceeded those that were recently reported using surface modified stainless steel-based catalysts for OER in alkaline condition. Moreover, the (Fe/Ni)(P/S) nanorods showed a remarkable Tafel slope of 65.7 mV dec⁻¹ with stable activity beyond two months with only 2.5% fluctuation. The above outstanding performance could be attributed to the unique morphology with highly exposed active sites and the control of electronic structure by co-treatment with P and S. This work presents an efficient way to modify SSM for use as an inexpensive and durable OER catalyst.