1T-Rich MoS₂ and Its Enhanced Hydrogen Evolution Reaction (HER) Activity by Functionalization With Organic Ammonium...

Molybdenum disulfide (MoS₂), specifically in its 1T-phase, is of significant interest as a catalyst for the hydrogen evolution reaction (HER) via water splitting. However, 1T-MoS₂ is metastable and gradually converts to the thermodynamically stable but less catalytically active 2H-phase, leading to a marked decline in HER activity. In this work, we demonstrate that functionalization with anilinium (ANI) monocation and para-phenylenediammonium (PPDA) dication can effectively stabilize 1T-MoS₂. The powder X-ray diffraction, electron microscopy, and Raman spectroscopy data confirm that as-synthesized ANI@1T-MoS₂ and PPDA@1T-MoS₂ samples retain a significant fraction of 1T-phase over time. These catalysts exhibit hydrogen evolution rates of 5.7 and 4.6 mmol g^-1 h^-1 of H₂, respectively, which are significantly higher than that of 2H-MoS₂ (1.7 mmol g^-1 h^-1) and are close to the activity of as-made 1T-MoS₂ (10.9 mmol g^-1 h^-1). These results suggest successful stabilization of 1T-MoS₂ and offer a valuable strategy for simultaneously enhancing both stability and catalytic activity.