Amorphous-Amorphous Coupling Enhancing the Oxygen Evolution Reaction Activity and Stability of the NiFe-Based Catalyst.

Efficient and stable electrocatalytic water splitting plays a critical role in energy storage and conversion but is strongly restricted by the low activity and stability of catalysts associated with the complicated oxygen evolution reaction (OER). This work provides a strategy to fabricate an advanced NiFe-based catalyst to steadily speed up the OER based on a strong amorphous-amorphous coupling effect generated through amorphous CuS that induces the formation of amorphous NiFe layered double hydroxide (LDH) nanosheets (A-NiFe NS/CuS). The presence of the strong coupling effect not only modifies the electronic structure of catalytic sites to accelerate the reaction kinetics but also enhances the binding between the catalyst and substrate to strengthen the durability. In comparison to well-grown core-shell crystalline NiFe LDH on CuO, the as-synthesized amorphous A-NiFe NS/CuS gives a low overpotential of 240 mV to achieve 100 mA cm ^-2 and shows robust stability under 100 h of operation at the same current density. Therefore, amorphous-amorphous coupling between catalyst-substrate by elaborate and rational engineering yields an opportunity to design efficient and robust NiFe-based OER catalysts.