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

The advances in functional electrocatalysts for real-time 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 hydrothermal 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 NiCo-MOF/NF demonstrates significant HER/OER performance with a small overpotential of 140/270 mV at 10 mA/cm 2 under alkaline and 252/340 mV at 10 mA/cm 2 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/cm 2 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.