Template-Driven Phase Selective Formation of Metallic 1T-MoS2 Nanoflowers for Hydrogen Evolution Reaction

The exploration of MoS2 based catalyst has been growing over the recent years, mainly focusing on fine-tuning the metallic phases for improved catalytic activity in the hydrogen evolution reaction (HER). Considering the synthesis of MoS2, the 2H phase (trigonal prismatic, D3h) is more stable than the 1T phase (octahedral, Oh). Still, with the increased electronic conductivity, hydrophilic nature, and the presence of electrochemically active basal planes, the 1T phase shows enhanced catalytic activity compared to the 2H phase which shows semiconducting nature with only edge sites being active. So far, one of the best ways to synthesize 1T-MoS2 is the alkali metal exfoliation, but a setback to this method is that there are many issues like intercalation of alkali ions, self-heating, and pyrophoric nature associated with it. Moreover it requires undesirable and expensive organic solvent to produce 1T phase. The aqueous phase synthesis of 1T-MoS2 is still hampered by the low extent of 1T enrichment and reproducibility. Here, in contrast, by the introduction of Santa Barbara Amorphous-15 (SBA-15) as a template, the selective formation of the 1T phase in MoS2 over 90% has been achieved. This is the very first observation of phase selectivity behavior of SBA-15 for the entire layered materials. Moreover, the reproducibility of this methodology is also ensured by repeating the experiment 14 times. Besides, the storage stability of the 1T-MoS2 at room temperature (RT) has been analyzed by storing it at RT over 30 days, which is essential for commercialize the methodology. Therefore, this reporting methodology resolving all the existing problems in aqueous phase synthesis of 1T-MoS2 such as enhancement in the 1T phase, reproducibility, room temperature storage stability, and large scale production. This template-driven 1T-MoS2 has demonstrated an excellent activity, and to attain 10 mA cm–2, it required just 252 mV with a low Tafel slope value of 45 mV/decade. These findings will pave a way to other similar 2D materials for selective enrichment in the 1T phase, which is the more desirable phase for energy storage and conversion devices at present.