Facile Surface Modification of Ubiquitous Stainless Steel Led to Competent Electrocatalysts for Overall Water Splitting

Competent and low-cost electrocatalysts play a crucial role in the wide deployment of electrocatalytic water splitting for clean H-2 production. Herein, for the first time, we report that readily available stainless steel can be transformed to competent electrocatalysts for both H-2 and O-2 evolution reactions (HER and OER, respectively) after facile surface modification. Specifically, our sulfurized stainless steel foil (SSFS) could achieve a catalytic current density of 10 mA cm(-2) at overpotentials of 136 and 262 mV for HER and OER, respectively, in 1.0 M KOH. When SSFS served as the electrocatalysts for both the cathode and the anode, an overall water splitting current density of 10 mA cm' was obtained at 1.64 V with robust durability. Such a superior performance can rival those of many recently reported water splitting catalysts that consist of expensive elements, contain high cost supports, or require sophisticated synthesis. In addition, excellent water splitting activity was also achieved by SSFS in neutral media, largely expanding its working conditions. Finally, we further demonstrated that analogous phosphorization and nitridation treatments also could substantially enhance the electrocatalytic performance of stainless steel for water splitting, suggesting the great versatility of our surface modification strategy.