Collective behaviors mediated multifunctional black sand aggregate towards environmentally adaptive solar-to-thermal purified water harvesting

• Published in: Nano energy 2020-02, Vol.68, p.104311, Article 104311
• Main Authors: Ni, Feng, Xiao, Peng, Qiu, Nianxiang, Zhang, Chang, Liang, Yun, Gu, Jincui, Xia, Junyuan, Zeng, Zhixiang, Wang, Liping, Xue, Qunji, Chen, Tao
• Format: Article
• Language: English
• Subjects: Collective behaviors; Multifunction; Purified water collection under changeable environments; Sand aggregate; Solar energy
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2019.104311

As a renewable and efficient technology, interfacial solar heating has emerged as a new and promising avenue for treating undrinkable water to clean one via a variety of well-designed solar absorbers. However, it is still urgent to develop an accessible material system in a simple, low-cost and effective way to easily tackle water shortage. Inspired by natural sand with highly important role in purifying water during the natural recycling, in this work, we demonstrate a concept of an all-round black sand aggregate with specific collective behaviors for environmentally adaptable clean water collection from seawater, polluted water and even atmospheric moisture. To endow the raw sand desirable photo-thermal features, polydopamine and Cl−-doped polypyyrole are successively modified onto the sand surface for a stable structure. Owing to the specific aggregative structure of the black sands, a self-channelled device combined adjustable 2D/3D solar-driven evaporation can be readily achieved, and yield a high evaporation performance (1.43 kg m−2 h−1) in comparison with other reported naturally derived materials. Notably, the black sand aggregate could handle with oil-contained polluted water (P-WA) to guarantee high-efficient and sustainable water purification. Furthermore, even if in some draughty areas or deserts, the collective black sands could also extract water from air by absorbing atmospheric moisture and sequentially realizing an in situ water evaporation by heat location. The successful demonstration of multifunctional black sand aggregate may provide a new avenue for purified water collection under changeable environments. In this work, natural sand has been tailored into photothermal black one for a self-channelled multifunctional solar-to-thermal evaporator by rational introduction of polydopamine (PDA) and polypyrrole (PPy) onto the sand particle surface in a cost-effective, scalable and accessible way. The collective behaviors have endowed the achieved black sand hybrids with pores in micro scale for desirable water pumping in the process of effective solar driven seawater evaporation. Moreover, the collective black sand aggregate can further function as the oil-water emulsion separator to realize a high-efficient and sustainable evaporation under the condition of industrial and/or domestic polluted water. More interestingly, the black sand aggregate can even extract moisture from the surrounding atmosphere, demonstrating significant potentials in