Interface construction of NiCo LDH/NiCoS based on the 2D ultrathin nanosheet towards oxygen evolution reaction

Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis. Oxygen evolution reaction (OER) as anodic reaction determines the overall efficiency of water electrolysis due to sluggish OER kinetics. Thus, it's much desirable to explore the efficient and earth-abundant transition-metal-based OER electrocatalysts with high current density and superior stability for industrial alkaline electrolyzers. Herein, we demonstrate a significant enhancement of OER kinetics with the hybrid electrocatalyst arrays in alkaline via judiciously combining earth-abundant and ultrathin NiCo-based layered double hydroxide (NiCo LDH) nanosheets with nickel cobalt sulfides (NiCoS) with a facile metal-organic framework (MOF)-template-involved surface sulfidation process. The obtained NiCo LDH/NiCoS hybrid arrays exhibits an extremely low OER overpotential of 308 mV at 100 mA·cm−2, 378 mV at 200 mA·cm−2 and 472 mV at 400 mA·cm−2 in 1 M KOH solution, respectively. A much low Tafel slope of 48 mV·dec−1 can be achieved. Meanwhile, with the current density from 50 to 250 mA·cm−2, the NiCo-LDH/NiCoS hybrid arrays can run for 25 h without any degradation. Our results demonstrate that the construction of hybrid arrays with abundant interfaces of NiCo LDH/NiCoS can facilitate OER kinetics via possible modulation of binding energy of O-containing intermediates in alkaline media. The present work would pave the way for the development of low-cost and efficient OER catalysts and industrial application of water alkaline electrolyzers.