Superhydrophilic MoS2@Polypyrrole hydrogel with dual photothermal-water activation properties for synergistic solar steam generation

Most hydrogels are composed of polymer chains lacking efficient light-absorbing groups, which presents a significant challenge for achieving high photothermal conversion efficiency and severely hinders the advancement of solar-driven interfacial evaporation technologies. In this study, a mechanically robust and conductive polypyrrole (PPy) hydrogel was successfully fabricated via oxidative polymerization combined with a secondary growth strategy. The resulting hydrogel exhibits an ultrahigh solar absorption efficiency of up to 98 % and achieves an evaporation rate of 3.85 kg m −2  h −1 under one sun illumination. To further enhance performance, molybdenum disulfide (MoS₂) nanosheets were introduced to regulate sulfur vacancies, thereby boosting the photothermal conversion efficiency of the MoS₂/PPy hydrogel. Additionally, the incorporation of MoS₂ optimized the hydrogel microstructure, suppressed salt accumulation, and promoted the formation of micro-meniscus structures and water droplets. These features effectively activated water molecules and reduced the evaporation enthalpy, resulting in a further increase in evaporation rate to 4.34 kg m −2  h −1 . This work offers a promising strategy for designing next-generation hydrogel-based solar evaporators that integrate high photothermal conversion efficiency, low evaporation enthalpy, and efficient water transport channels.