MoS2 nanosheet initiated smart polymeric hydrogel for NIR-driven Ag(I) enrichment

Molybdenum disulfide (MoS2) nanosheet is an appealing material due to its various merits such as narrow bandgap, high photothermal conversion speed, and intrinsic sulfur-rich properties. Building up a MoS2-based smart material with all the merits combined has become a challenging topic. Herein, using the monomer N-isopropylacrylamide (NIPAM), a MoS2 self-initiated hydrogel adsorbents was fabricated by manipulation of MoS2 nanosheets as a photoinitiator response to UV light. The hydrogel adsorbent presents a high selectivity to Ag+, and can be quickly recycled upon the photothermal effect induced by 808 nm near-infrared laser irradiation. The adsorption-desorption cycle can be repeated for at least 6 times without obvious decrease of the Ag+ adsorption capacity. The entropy change associated with the desorption process is −16.7 J·K−1·mol−1, which confirms a spontaneous NIR-induced Ag+ desorption. Our MoS2-based smart hydrogel proves to be energy-efficient, quick-regenerated material for Ag+ enrichment.