NiCo-Metal Organic Frameworks for Highly Stable Electrocatalytic Water Splitting under Alkaline and Neutral pH Ranges

The advances in functional electrocatalysts for realtime production of green hydrogen gas under alkaline and neutral pH ranges are highly desirable. Toward the goal, spatially arranged Ni-Co building blocks in metal-organic frameworks (MOF) structures were synthesized on Ni foam by a one-step hydro thermal approach and demonstrated for overall water splitting. Interestingly, the proposed NiCo-MOF/NF shows superior performance for both hydrogen/oxygen evolution reactions (HER/OER) with a small overpotential (vs reversible hydrogen electrode (RHE)) under alkaline/neutral conditions. The NiCoMOF/NF demonstrates significant HER/OER performance with a small overpotential of 140/270 mV at 10 mA/cm2 under alkaline and 252/340 mV at 10 mA/cm2 under neutral pH conditions. In addition, NiCo-MOF/NF demonstrates stable overall water splitting performance in a two-electrode configuration with a current density of 20 mA/cm2 at the low cell voltage of 1.60 V and excellent stability over 140 h. The improved performance of the electrocatalyst can be associated with the synergistic effect of Ni-Co bimetal clusters in the MOF matrix and the rapid charge transfer kinetics of the catalyst. NiCo-MOF can be an ideal high-performance and stable electrocatalyst for pilot-scale water splitting applications under alkaline and neutral electrolyte conditions.

Automated summary

In this study, a new electrocatalyst NiCo-MOF/NF was synthesized by arranging Ni-Co building blocks in a metal-organic frameworks structure, and it exhibited superior performance for overall water splitting under alkaline and neutral conditions. The NiCo-MOF/NF showed small overpotential and stable performance for both hydrogen and oxygen evolution reactions.