Liquid Nitrogen Exfoliation and Nanodispersion of WS₂ for Thermocatalysts

The efficient and clean exfoliation of single and/or few-layer nanosheets of WS₂, a two-dimensional transition metal dichalcogenides, remains a significant challenge. In this study, a simple exfoliation method was proposed to produce ultrathin WS₂ nanosheets by combining the liquid nitrogen exfoliation and nanodispersion techniques. This approach efficiently exfoliated WS₂ into several layers of nanosheets via rapid temperature changes and mechanical stress without inducing defects or contamination. After five cycles of heating/liquid nitrogen and nanodispersion, the resulting WS₂ nanosheets (WS₂-5N ND) were confirmed to have been successfully exfoliated into 1-4 layers. When applied as a promoter in a thermocatalyst for the selective catalytic reduction of NO_X using NH₃, 2V3WS₂/Ti (WS₂-5N ND) exhibited excellent NO_X conversion and N₂ selectivity, along with excellent durability even in the presence of SO₂. This result was greater than 2V3WS₂/Ti (WS₂-5N) subjected to only liquid nitrogen exfoliation, proving the importance of the simultaneous action of both methods. This method is expected to be an important contribution to ongoing research on high-performance WS₂-based catalysts, thereby opening up potential opportunities for a wide range of applications.