Chlorine corrosion of ubiquitous rust towards low-cost, efficient and free-standing electrocatalysts for overall water splitting.

High-efficiency and low-cost electrocatalysts play an important role in clean hydrogen production through electrocatalytic water decomposition. Therefore, it is of great significance to develop an effective method to retrieve rusty stainless steel and facilitate the slow oxygen evolution reaction (OER) for an environment-friendly and sustainable society. Herein, we developed a method to synthesize Fe–Ni bimetallic hydroxide (RSS-LDH) using chloride ions to corrode rusty stainless steel, which can be used as an efficient and cheap catalyst for OER and hydrogen evolution reaction (HER). We found that RSS-LDH has good electrocatalytic performance toward OER (η100 = 340 mV) and HER (η100 = 310 mV). In addition, RSS-LDH can be used as an active bifunctional catalyst in overall water splitting with a low cell voltage of 1.42 V at 10 mA cm−2 (1.64 V at 100 mA cm−2) and stable operation of 10 h (100 mA cm−2). This strategy can provide a new method for the recovery of rusty stainless steel and provide a new application for electrocatalysis and energy transformation. [ABSTRACT FROM AUTHOR]