太阳能蒸发器为应对全球淡水短缺问题，提供了一种可持续且高效的水净化解决方案。尽管此前的研究在最大化水蒸发速率方面取得了显著进展，但尚无单一蒸发器具备实际应用所需的所有特性，如生成饮用水的高效性、用于现场水净化的优异便携性、减少蒸发器结垢的良好可清洗性，以及良好的可重复使用性。
近日，中国科学院深圳先进技术研究院成会明院士和清华大学苏阳副教授等人在Science China Materials发表研究论文，提出了一种用于即时水净化的高性能光热材料制备策略，通过在具有优异机械性能的海绵中同时引入石墨烯和从电子垃圾中提取的金颗粒，实现了高效水净化。
本文要点
- 在一个太阳光强度照射下水蒸发速率达到3.55 kg/m2/h，这得益于对石墨烯原子结构的控制以及金纳米颗粒尺寸依赖性表面等离子体共振效应。
- 该材料便携性强，可折叠、可真空压缩、干燥、再使用而不影响性能，且可以通过反复清洗去除污染物结垢，从而实现重复使用。
- 该蒸发器可以将多种类型的污染水转化为可饮用的清洁水，并且可以任意角度安装，便于追踪太阳入射角，实现太阳光的高效利用。所组装的蒸发器在户外阳光下的水蒸发速率高达9.36 kg/m2/h，所产出的净化水符合世界卫生组织的饮用水标准。
Figure 1. Preparation of GRAMS and its portability. (a) Schematic of the preparation of GRAMS. (b) SEM images of MS, GMS, and GRAMS. Scale bar: 50 μm. The insets in (b) are high-magnification SEM images of MS, GMS, and GRAMS. Scale bar of insets of MS, GMS, and GRAMS are 2 μm, 2 μm, and 500 nm, respectively. (c) Schematic of a portable GRAMS steam generator.
Figure 2. Solar steam generation performance of GRAMS and mechanism study. (a) Mass changes of evaporated water versus time for various samples under one-sun illumination. Inset is a schematic of the device for solar-driven water evaporation. (b) Water evaporation enthalpy of pure water and water in MS, GMS, and GRAMS. (c) IW/FW ratio of pure water and water in MS, and GMS with different reduction times. The sample “GMS-HI” refers to GMS reduced by ascorbic acid for 120 min and further reduced by hydroiodic acid (HI). The inset is the Raman spectrum showing the fitted peaks representing IW and FW in GRAMS. (d) Evaporation rates of water in GMS with different reduction times. The dashed lines are the evaporation rates of pure water (black), water in MS (blue), and GO-MS (green). Inset is a photo of the release of water vapor.
Figure 3. Solar-driven desalination and water treatment of GRAMS. (a) Stability of continuous seawater evaporation rates for 12 h under one-sun irradiation. (b) Ion concentrations of seawater before and after desalination. (c) UV-vis spectra of dye-contaminated water before and after photothermal water purification. Inset is a photograph of dye-contaminated and purified water. (d) Antibacterial performance test. Optical images of agar plates before and after purification of water contaminated with E. coli under one-sun irradiation. The purified water shows no visible colonies of bacteria. (e) Heavy metal ion concentrations in contaminated water before and after purification. (f) Photographs of the GRAMS, before (left), after 7-h evaporation of 25 wt% brine (middle), and after then washing by squeezing it in pure water (right). (g) Evaporation rates of 25 wt% brine under continuous one-sun irradiance (1 kW/m2) for 15 cycles. (h) Long-term stability of the evaporation rate of GRAMS for 3.5 wt% seawater purification under one-sun illumination for 30 days with 6 h illumination per day. The inset shows the ion concentrations of brine before and after desalination.
Figure 4. A portable GRAMS evaporator for point-of-use solar steam generation. (a) Water evaporation performance of tilted GRAMS with sunlight normal to the sample. (b) Pictures of a portable GRAMS solar tree. 1. A large-area GRAMS that can be cut into 16 pieces. 2. A vacuum package. 3. An unsealed on-the-go solar tree device containing 16 pieces of GRAMS and a solar tree stem. 4. An assembled solar tree. (c) Photographs of the solar-driven clear water collection by GRAMS using sanitized a recycled plastic bottle under one-sun irradiation. (d) Ion concentrations in seawater (upper panel) and river water (lower panel) before and after purification by GRAMS under outdoor irradiation (~0.5 sun). (e) A radar plot comparing GRAMS and a pure rGO hydrogel regarding their point-of-use solar steam generation performance.
文章信息
Fei Li, Jiongpeng Huang, Dingxin Xu, Chengjin Wang, Liang Zhao, Xinyu Gong, Hang Li, Can Yang Zhang, Qinghua Song, Yang Su, Hui-Ming Cheng. A portable and washable solar steam evaporator based on graphene and recycled gold for efficient point-of-use water purification. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3089-2
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