A super hygroscopic hydrogel for harnessing ambient humidity for energy conservation and harvesting

Nandakumar, Dilip Krishna; Ravi, Sai Kishore; Zhang, Yaoxin; Guo, Na; Zhang, Chun; Tan, Swee Ching

doi:10.1039/c8ee00902c

Cited by 141 publications

(112 citation statements)

References 40 publications

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“…As for higher RH (85.0%) with this hybrid (Figure b), the gap of absorbed water weight in the dark/under illumination is 31.7 and 36.5 mg for Zn and Co hydrogel hybrid (considering the LED affect). These results declare that the decreased water must be split by (100)/(111) Cu 2 O@BTO, however, the amount of split water is far less than the hydrogel absorbed water (around 450 mg), stating that the split water can be compensated by hydrogel . Besides, the amount of produced gas was detected by gas chromatography, identifying that the water splitting again on account of the proportion of hydrogen and oxygen is almost 2:1 (Figure S19, Supporting Information).…”

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A Hybrid Artificial Photocatalysis System Splits Atmospheric Water for Simultaneous Dehumidification and Power Generation

et al. 2019

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A new approach for artificial photocatalysis of electrical generation directly from atmospheric water is reported. A hybrid system comprising a hydrogel incorporated with Cu2O and BaTiO3 nanoparticles is developed, wherein the Cu2O is designed to expose two different crystal planes, namely (100) and (111). These planes exhibit different surface potentials and form a polarization electric field of 2.3 kV cm−1 that acts on a ferroelectric dipole. With the help of this electric field, the dipole is redirected for aiding in positive and negative polarizations with (100) and (111) planes, then boosting water reduction and oxidation kinetics separately at (100) and (111) planes. Additonally, zinc‐/cobalt‐based superhygroscopic hydrogels serve as a water‐capturing “hand” to harness humidity from the ambient environment. The integrated hydrogel–Cu2O@BaTiO3 hybrid is used to dehumidify air, which can split 36.5 mg of water by employing only 150 mg hydrogel and simultaneously generate a photocurrent of 224.3 µA cm−2 under 10 mW cm−2 illumination.

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“…But, the inadequacies of these materials are poor humidity absorption rate and low quantity of saturated value. According to a recent report on zinc‐based hydrogel exhibiting the humidity harvested behavior, a new cobalt‐based hygroscopic hydrogel has been developed and deployed to fetch atmospheric humidity for water splitting.…”

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A Hybrid Artificial Photocatalysis System Splits Atmospheric Water for Simultaneous Dehumidification and Power Generation

et al. 2019

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“…The structure and characterization of the hydrogel was reported in our earlier work . This amorphous superhygroscopic hydrogel, made up of Zn and O atoms in a unique ratio of 1:1.1 ( Figure a) has a strong tendency to attract moisture from the air owing to its nano porous and fringed contours (Figure b–d) that offer an enormous surface area for absorption of moisture from atmosphere and the weak binding forces of water with the material.…”

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confidence: 84%

Solar Energy Triggered Clean Water Harvesting from Humid Air Existing above Sea Surface Enabled by a Hydrogel with Ultrahigh Hygroscopicity

et al. 2019

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diminishing groundwater resources, mitigated river flows, dwindling lakes, and heavily polluted water. The challenge of providing sufficient and safe freshwater is limited by population growth, climatic changes, industrialization, and contamination of available freshwater sources. [1][2][3][4][5][6] In its latest annual risk report, the world economic forum ranks water crisis as a major global risk in terms of its potential impact. Many problems associated with the scarcity of water not only are restricted to around four billion people lacking access to safe and pure drinking water at least one month of the year, [3,7] high mortality rates, instigation of civil or international conflicts [8,9] but also pose a severe threat to industries, affecting operations and supply chain. [2] The most common reason attributed to this is that only about 3% of the earth's water resources is fresh and the rest is saline and unpalatable. Of the fresh water sources, 2.5% is locked up in the form of glaciers in the Arctic and Antarctic regions and are unavailable for use. Thus humanity, for its sustenance, must rely only on the 0.5% of the total water resources which is stored as underground aquifers, flowing rivers, natural lakes, and manmade storage facilities.Several alternative approaches of water harvesting have been developed lately. These include water harvesting from ambient humid atmospheres using hydrophobic surfaces for easy water condensation, [10] purification of water accompanying the production of shale gas, [11] water harvesting from fog [12,13] using special structures, dewing, [14,15] disinfection and decontamination of polluted water sources, [7,16,17] and desalination of seawater. Inspired by the unique water harvesting abilities of cacti [18] and some of the beetles of the Namib desert, [19] synthesis of biomimetic structures using copper [20,21] and branched ZnO nanowires [18] have been employed for water collection. Fog collectors, employing the principle of forcing fog droplets through a mesh for water collection have been employed recently in many African and European countries to harvest fresh water from moving clouds. [13] However these alternative sources contribute only to a very small fraction of the actual demand for fresh water, which widely varies demographically and totals to a staggering value of ten billion tons per day. [22] Water scarcity is a ubiquitous problem with its magnitude expected to rise in the near future, and efforts to seek alternative water sources are on the rise. Harvesting water from air has intrigued enormous research interest among many groups with Scientific American listing this technology as the second most impactful technology that can bring about a massive change in people's lives. Though desalination offers a huge prospect in mitigating water crisis, its practicality is limited by exorbitant energy requirement. Alternatively, the air above sea water is moisture rich, with the quantity of vapor increasing at the rate of 0.41 kg m −2 . Herein, a method to sustainably h...

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“…[ 156 ] By combining with hydroscopic materials such as the hydrogel demonstrated by Tan and co‐workers recently, the generated water vapor was split into hydrogen and oxygen in an hybrid artificial photocatalysis system. [ 157,158 ] In this view, although there seems to be not much margin for improvement of conversion efficiency of solar evaporation, it has exhibited promising potential in playing a role to facilitate interesting and constructive interdisciplinary studies between different energy application fields. In addition to the interesting interdisciplinary combinations with solar evaporation, practical feasibility of these integrated systems should also command our attention.…”

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Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

et al. 2020

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requirement has given rise to research thrusts being focused on the development of solar-driven evaporation based desalination technologies. [4][5][6][7] The research on using solar energy in the desalination process has a long history. [3,8,9] In a traditional singleslope basin-like solar still (Figure 1a), saline water is heated and subsequently evaporated by directly exposing to solar radiation. Solar energy is absorbed and converted into thermal energy by a black light-absorbing liner that is situated at the bottom of the solar basin. [10] Due to this design, the solar absorber is immersed in bulk seawater and it hardly receives a fraction of the incoming solar radiation owing to poor light penetration through the thick water layer. Furthermore, the produced heat is easily dissipated into the bulk water, and further lost to the surroundings through water surface radiation, convection and conduction. Due to the above reasons, the resulting solar-tosteam conversion efficiency is inevitably low. Nanoparticle dispersed fluid was then demonstrated to harness solar energy and found to be a great boon to direct water vapor generation. [11,12] A solar conversion efficiency of up to ≈70% can be possibly achieved because heat loss to bulk water is mitigated ( Figure 1b). [13,14] However, research on this advancement didn't last because of the development of solar interfacial heating strategy, which is shown in Figure 1c. The concept of interfacial evaporation was first put forth in 2014 by two reports simultaneously, [15,16] and received a surge of attention and interest immediately in the following years. The most prominent feature of solar interfacial evaporation lies in the position of the solar absorber, which is at the interface between saline liquid and the above air. This special configuration not only minimizes heat loss from the solar absorber to bulk water, but also provides significantly more surface area for prompt vapor release. Also, solar radiation is photothermally localized at the surface of solar absorber, giving rise to high surface temperature, which enables fast heat transfer to water. With it, water transported from reservoir can be heated and evaporated immediately to achieve a higher rate of steam generation. In addition to the differences in heating strategies, it should be noted that all the solar stills follow the same evaporation-condensation route for desalination and clean water collection, and to this end, a similar device structure (e.g., solar still with sloping cover) is usually employed.The past few years have witnessed a rapid development of solar-driven interfacial evaporation, a promising technology for low-cost water desalination. As of today, solar-to-steam conversion efficiencies close to 100% or even beyond the limit are becoming increasingly achievable in virtue of unique photothermal materials and structures. Herein, the cutting-edge approaches are summarized, and their mechanisms for photothermal structure architecting are uncovered in order to achieve ultrahigh conversion e...

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A super hygroscopic hydrogel for harnessing ambient humidity for energy conservation and harvesting

Abstract: Atmospheric humidity, an abundant source of water, is widely considered as a redundant resource demanding expense of energy to maintain it under comfortable levels for human habitation.

Cited by 141 publications

References 40 publications

A Hybrid Artificial Photocatalysis System Splits Atmospheric Water for Simultaneous Dehumidification and Power Generation

A Hybrid Artificial Photocatalysis System Splits Atmospheric Water for Simultaneous Dehumidification and Power Generation

Solar Energy Triggered Clean Water Harvesting from Humid Air Existing above Sea Surface Enabled by a Hydrogel with Ultrahigh Hygroscopicity

Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

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