Self-generated N-doped anodized stainless steel mesh for an efficient and stable overall water splitting electrocatalyst

In this work, N-doped anodized stainless-steel mesh (NASSM) with mesoporous structure is demonstrated as a highly efficient, stable and bifunctional electrocatalyst with tuned electronic structure and surface morphology. NASSM was fabricated by anodic oxidation with Cr as non-catalytic substance by in situ removal of the SSM surface to regulate the morphology with mesoporous structure, followed by nitrogenization. NASSM showed an overpotential of 225 mV at 10 mA cm⁻², which exceeded that of commercial IrO₂/C catalyst, with a low Tafel slope of 49.7 mV dec⁻¹ and excellent stability for over 100 h. NASSM exhibited an overpotential of 146 mV at 10 mA cm⁻² and a Tafel slope of 60.1 mV dec⁻¹. NASSM, as a bifunctional electrocatalyst, showed potentials of 1.61 and 1.76 V at 10 and 50 mA cm⁻², respectively, for overall water-splitting with only a 0.01 V increase after a long-term stability test. These values are superior to those reported for directly modified SS-based bifunctional electrocatalysts. The remarkable catalytic properties of NASSM could be attributed to the tuning of not only electronic structure but also surface morphology. This work reports an efficient approach to synthesize and tune an effective and low-cost bifunctional catalyst based on SSM for large-scale application.