Pulsed laser rusted stainless steel: A robust electrode material applied for energy storage and generation applications

In terms of global energy needs, fabrication of robust electrode materials with superior energy storage performance and excellent energy generation activity is significant. We demonstrate for the first time the use of pulsed laser rusting strategy for transmuting stainless steel (SS) into an active electrode that is used as an energy storage system of supercapacitors (SCs), and as an electrocatalyst for oxygen evolution reaction (OER). Herein, the bare stainless steel (denoted as BARE-SS) electrode is rusted on single side (designated as SSLR-SS) as well as on double side (represented as DSLR-SS) by means of Nd:YAG laser pulse. Because of the unique honey-comb texture consists of highly conductive Fe-Cr-Ni oxide/oxyhydroxide rust layers, endows shorter diffusion path for electrons and ions. Therefore, the as-rusted electrodes possess preferred electrochemical active sites enabling the effective contact between them with electrolyte (1 M KOH). The electrochemical measurements reveal that associated with the BARE-SS and SSLR-SS electrodes, the DSLR-SS electrode unveils improved capacitive behavior, including satisfactory areal capacitance (22 µFcm-2 at 5 mVs-1). Meanwhile, the DSLR-SS electrode has concurrently accomplished well as an electrocatalyst for OER and can attain a current density of 10 mA cm-2 at a low overpotential of 382 mV with a Tafel slope of 52 mV dec-1. These findings shed light on the economic pathway to prepare pulsed laser rusted metallic alloys and to handle multifunctional challenges in the fields of energy.