Amorphous cobalt-manganese sulfide electrode for efficient water oxidation: Meeting the fundamental requirements of an electrocatalyst

Design and development of efficient and low-cost electrocatalysts for oxygen evolution reaction (OER) remain a challenge due to high overpotential, low stability, and scalability issues. As a realistic solution, herein, amorphous (Co-Mn)S tailored into nanosheets is demonstrated as a highly efficient and stable electrocatalyst for OER. Thin films of (Co-Mn)S are deposited on stainless steel (SS) substrates via a scalable successive ionic layer adsorption and reaction (SILAR) method for the first time. The stoichiometric tuning of composition has effectively augmented the electrocatalytic activity and OER performance by modification of electronic structure and binding strength with the intermediates. The tailored nanosheet like morphology resulted in achieving high current density at low overpotential. Benefited from the synergy of redox chemical properties and a binder-free deposition, (Co3Mn2)S thin film electrocatalyst achieved a current density of 10 mA cm−2 at an overpotential of 243 mV in 1 M KOH electrolyte. On top of that, the electrocatalyst displayed excellent stabilities over 100 h of continuous water oxidation without any apparent change. In view of the simple yet scalable approach of synthesis, and excellent OER performance, amorphous (Co-Mn)S thin film electrocatalyst could be deliberated as a promising candidate for large application of OER.