Abstract: The Ag@DMSNs composite was prepared by synthesizing the dendritic mesoporous silica nanoparticles (DMSNs) and subsequently loading the nanostructured Ag in the pore channels of the DMSNs via chemical reduction. Thus-obtained Ag@DMSNs feature an intensive and board absorption for the solar irradiation due to the plasmonic coupling of Ag nanostructures, which are anchored in the pore channels of DMSNs and not prone to aggregation. More importantly, the thermal effect of plasmonic relaxation can efficiently convert solar energy into heat. For example, Ag@DMSNs can increase its surface temperature from 26 ℃ to 70 ℃ within 5 minutes under one sun (1 kW·m^-2, 420~2500 nm) . When Ag@DMSNs are loaded on the porous polyurethane foam material, the water evaporation rate reaches 1.10 kg·m^-2·h^-1 under one sun, and they also exhibit excellent stability in simulated seawater. In addition, the thermal electrons produced during the relaxation of the Ag nanoparticle plasmon in the Ag@DMSNs complex can effectively remove contaminants from water, such as the degradation of methylene blue. These results show that it is an effective way to realize solar-powered clean water production by rational construction of the plasmonic coupling model and utilizing the thermal and hot-electron effect of plasmonic relaxation process, opening new avenues to tackling the deteriorating problem of fresh water scarcity.

Key words: plasmon, nanostructured silver, mesoporous silica, solar interfacial evaporation, photothermal conversion