Anion Intercalation-Assisted Sustainable Phase Engineering of 1T MoS2/N, S-Doped Hollow Carbon Spheres for Accelerated HER Kinetics

Abstract

Intercalation-induced phase engineering of MoS2 has predominantly relied on cationic and molecular intercalants, while the use of anionic species remains less explored despite their potential to tailor the electronic structure and catalytic behavior. In this work, a sustainable aqueous synthesis route was employed to systematically investigate oxalate, citrate, and phosphate anions as intercalants for inducing and stabilizing the metallic 1T phase of MoS2. To address the intrinsic conductivity limitations and improve active-site utilization, the intercalated MoS2 was in situ integrated with nitrogen and sulfur-doped hollow carbon spheres through a dual-engineering strategy. The conductive and defect-enriched carbon framework facilitated rapid charge transfer and improved the dispersion and accessibility of catalytic sites, leading to a stabilized 1T-MoS2/carbon hybrid architecture. The optimized catalyst delivered an overpotential of 200 mV at 10 mA cm–2, an electrochemical active surface area of 0.57 cm2, and outstanding operational durability over 5 days of continuous electrolysis. This work demonstrates the effectiveness of anion-driven phase engineering as a sustainable strategy for tailoring MoS2-based electrocatalysts and provides a scalable platform for developing efficient hybrid systems for hydrogen evolution reactions.