Engineering of interfacial active sites in composites of troilite phase nano-leaves interacting with nickel oxide adorned carbon nanotubes for robust overall water splitting

The advancement of facile, non-precious electrocatalysts remains highly relevant owing to their high inherent activity, increased exposure of active edges, and synergistically enhanced electronic structure. In this study, cubic-NiO/troilite-FeS hybrids embedded within 3D CNT skeleton networks were synthesized through a rapid, one-step hydrothermal process. Compared to the pristine structure, the NiO/FeS@CNT composite exhibited enhanced catalytic performance under alkaline conditions. It demonstrated low overpotentials of η_-10 ∼218 mV with a 52 mV dec^-1 Tafel slope for the oxygen evolution reaction, and η₁₀ ∼ 64 mV with a 38 mV dec^-1 Tafel slope for the hydrogen evolution reaction. The constructed NiO/FeS@CNT||NiO/FeS@CNT electrolytic cell exhibited an exceptionally small cell voltage of only 1.465 V at 10 mA cm^-2, which is significantly lower than in various reports in the literature. Hence, the NiO/FeS@CNT hybrid offers efficient catalytic activity and in-depth insight regarding the active sites for electrochemical water splitting in alkaline solution. © The Royal Society of Chemistry 2025.