Enhanced Electrocatalytic Oxygen Reduction to H₂O with High Selectivity via 2D 1T-MoS₂ Integrated with Functionalized Carbon Nanohorns

Developing cost-effective and high-performance electrocatalysts for the oxygen reduction reaction (ORR) is essential for advancing anion-exchange membrane fuel cell technologies. In this study, we report a robust heterostructure formed by covalently functionalized carbon nanohorns (CNH-N) integrated with metallic 1T-MoS₂ 2D nanosheets. Through tailored diazonium chemistry, positively charged ammonium groups were introduced onto CNHs, enabling strong electrostatic and van der Waals interactions with negatively charged exfoliated MoS₂. Structural and spectroscopic analyses confirm successful functionalization, enhanced defect modulation, and intimate CNH–MoS₂ coupling. The resulting CNH-N-MoS₂ catalyst exhibits remarkable ORR performance, including an optimized onset potential of 0.80 V, reduced charge-transfer resistance, and a dominant four-electron reduction pathway with ~ 94% selectivity toward H₂O, which is comparable to commercial Pt/C. These results highlight how controlled chemical functionalization and heterointerface engineering can synergistically enhance catalytic activity and stabilize the 1T-MoS₂ phase. The CNH-N-MoS ₂ heterostructures thus represent a promising class of metal-free/low-metal-content electrocatalysts for efficient fuel cell applications.