MOF-templated heterostructured CoS/NdS: driving interfacial charge transfer for efficient alkaline oxygen evolution...

Fabricating inexpensive and efficient electrocatalysts for the alkaline oxygen evolution reaction (OER) remains a critical challenge towards the practical implementation of renewable energy systems. Herein, we report a heterostructured CoS/NdS electrocatalyst obtained from a bimetallic Co/Nd-BDC MOF precursor. The uniform coverage of sulfur species over the Co and Nd regions is confirmed by morphological analysis, providing a strong interfacial interaction between CoS and NdS. The MOF-templated method enables the preparation of highly integrated nanoscale CoS/NdS heterointerfaces that favour interfacial charge redistribution and accelerate electron-transfer kinetics during anodic oxidation. In an alkaline electrolyte, the optimized CoS/NdS electrocatalyst demonstrates superior OER performance, requiring a low overpotential of 249 and 308 mV at current densities of 10 and 50 mA cm^-2 and exhibiting a minimum Tafel slope of 51.37 mV dec^-1. Chronoamperometry demonstrated the robust long-term electrochemical stability of CoS/NdS, which exhibited a high turnover frequency of 7.67 × 10^-2 s^-1 and an electrochemically active surface area of 918.25 cm². Brunauer-Emmett-Teller (BET) analysis shows that the CoS/NdS composite has high specific surface area and a well-developed mesoporous structure with porous channels that further facilitate electrolyte penetration and charge transfer, thus improving the OER properties of the catalyst. Furthermore, analytical techniques confirm that the coexistence of sulphur and oxygen species in CoS/NdS catalyst plays a crucial role in enhancing its intrinsic OER catalytic activity.