树枝状介孔二氧化硅负载纳米银用于太阳能驱动的清洁水生产

Dendritic Mesoporous Silica Loaded with Nanostructured Silver for Solar-driven Clean Water Production

合成了树枝状介孔二氧化硅纳米颗粒(Dendritic Mesoporous Silica Nanoparticles,DMSNs),随后通过化学还原法在其孔道中装载纳米银(Ag),最终得到Ag@DMSNs复合物。由于纳米银被固定在DMSNs孔道中,因此不易发生团聚,且纳米银的等离激元耦合效应使Ag@DMSNs在太阳辐射范围内具有强的广谱吸收。更重要的是,等离激元弛豫过程中的热效应可以将太阳能高效转化成热,例如,Ag@DMSNs在一个模拟太阳光照射下5 min内(1 k W·m^(-2),420~2500 nm)即可使其表面温度从26℃升温至70℃。将Ag@DMSNs负载于多孔的聚氨酯泡沫材料上,其在一个太阳辐照下的水蒸发速率可达到1.10 kg·m^(-2)·h^(-1),且在模拟海水中也能保持较好的稳定性能。此外,在Ag@DMSNs复合物中纳米银等离激元的弛豫过程中产生的热电子可以有效去除水中污染物,如降解亚甲基蓝。这些结果表明,合理构筑等离激元耦合模式,并利用等离激元弛豫过程中的热效应和热电子效应是实现太阳能驱动的清洁水生产的有效途径,这将为解决日益严峻的淡水稀缺问题提供新思路和新材料。

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 k W·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.