Crystalline–amorphous Ni4.5Fe4.5S8/NiFeS heterostructure for alkaline water oxidation electrocatalysis

Electrochemical water splitting, hailed for its cost-effectiveness and eco-friendliness in hydrogen energy production, faces a significant impediment in the form of the oxygen evolution reaction (OER), characterized by inherently slow kinetics. Addressing this challenge, the utilization of crystalline-amorphous (c-a) heterostructures, offering precise interface modulation, emerges as a promising solution. In this study, we report the synthesis of a robust electrode comprising of crystalline Ni4.5Fe4.5S8 nanospheres integrated with amorphous NiFeS nanosheets (denoted as NiFeS-TH) using a hydrothermal approach. Remarkably, this electrode exhibits exceptional performance in alkaline electrolytes, requiring a mere overpotential of 420 mV to attain a current density of 2 A/cm2. This enhanced OER performance is attributed to the substantial electrochemically active surface area and the presence of compressive strain at the interfaces. These profound insights into heterostructure design hold the potential to revolutionize the tailoring and optimization of OER efficiency.