A Portable Device Utilizing High-Entropy Perovskite Aerogels for Efficient Energy Conversion from Atmospheric Water

Environmental Engineering Energy Chemistry Chemistry Materials Science Inorganic Non-Metallic Materials Engineering Catalysis Energy Engineering Materials Chemistry
high-entropy perovskite aerogel solar evaporation water harvesting oxygen evolution reaction

Academic Background

The global scarcity of water and energy resources is particularly severe in arid and remote regions, and this issue has become even more urgent in the context of intensifying climate change. Traditional methods of water and energy acquisition, such as seawater desalination or large-scale power transmission, are not only costly and technically complex but also difficult to implement in resource-scarce areas. Therefore, the development of sustainable technologies capable of directly harvesting atmospheric moisture and converting it into clean water and energy has become a focal point of current research. Atmospheric Water Harvesting (AWH) technology provides a decentralized solution by utilizing natural resources such as dew and fog to supply clean water in arid and remote regions while reducing dependence on traditional centralized systems. However, integrating AWH technology with energy generation, particularly through electrocatalytic water splitting to produce hydrogen and oxygen, remains a challenging task.

Source of the Paper

The research was conducted by Yi Lu, Zongze Li, Guangyao Zhang, Hao Zhang, Deqi Fan, Ming Zhao, Han Zhu, and Xiaofei Yang, affiliated with Nanjing Forestry University, Jiangnan University, and the National University of Singapore. The paper was accepted on November 25, 2024, and published in the journal Advanced Fiber Materials, with the DOI 10.1007/s42765-024-00504-7.

Research Process

1. Material Preparation

The study first synthesized high-entropy perovskite fibers, La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 (referred to as LB5O3), using electrospinning and high-temperature calcination techniques. The specific steps are as follows: - Preparation of Precursor Solution: La(NO3)3·6H2O, Cr(NO3)3·9H2O, Mn(NO3)2·4H2O, Fe(NO3)3·9H2O, Co(NO3)2·6H2O, and Ni(NO3)2·6H2O were mixed with PVP, and DMF solvent was added. The mixture was stirred and ultrasonicated. - Electrospinning: The precursor solution was ejected through a G20 needle at a rate of 0.8 µl/min, with a voltage of 15 kV. The collected fibers were dried in a vacuum oven, pre-sintered at 300°C for 1 hour, and then calcined at 700°C for 2 hours. - Aerogel Preparation: Bacterial cellulose dispersion was mixed with polyvinyl alcohol, followed by the addition of HCl and glutaraldehyde. The mixture underwent freezing and in-situ polymerization, and the resulting hydrogel was freeze-dried to prepare the aerogel. The aerogel was then soaked in a LiCl solution to enhance its hygroscopic properties.

2. Device Design and Assembly

The study designed an integrated device capable of simultaneously generating clean water and energy through AWH and electrocatalytic water splitting. The main components of the device include: - Transparent Pyramid Cover: Used to capture atmospheric moisture. - Water Tank: Used to store the collected water. - Aerogel Electrodes: Composed of LB5O3 fibers and LiCl aerogel, used for electrocatalytic water splitting. - Gas Collectors: Used to separate and collect the generated hydrogen and oxygen.

3. Performance Testing

The study conducted detailed tests on the materials’ hygroscopicity, photothermal conversion efficiency, and electrocatalytic performance: - Hygroscopicity Testing: The water absorption capacity of the aerogel was tested under different relative humidity (RH) conditions. The results showed that the CA-LB5O3-LiCl aerogel achieved a water absorption rate of up to 1.44 g/g at 90% RH. - Photothermal Conversion Testing: Under 1 sun irradiation (0.1 W/cm2), the photothermal conversion efficiency of the LB5O3 fibers rapidly increased the surface temperature to 38°C, with a water evaporation rate of 2.1 kg/m2·h. - Electrocatalytic Performance Testing: In an alkaline environment, the LB5O3 fibers exhibited excellent oxygen evolution reaction (OER) activity, with an overpotential of only 290 mV and a Tafel slope of 54.4 mV/dec.

Main Results

1. Structure and Performance of High-Entropy Perovskite Fibers

Through X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis, the LB5O3 fibers exhibited a typical perovskite structure with abundant nanopores on the fiber surface. EDX elemental mapping showed that La, Cr, Mn, Fe, Co, Ni, and O were uniformly distributed throughout the fibers, with no signs of agglomeration.

2. Hygroscopicity and Water Release Performance of the Aerogel

The CA-LB5O3-LiCl aerogel demonstrated excellent moisture absorption under low humidity conditions, with a water absorption rate of 0.58 g/g·h at 30% RH, reaching 1.44 g/g·h at 90% RH. Under solar irradiation, the aerogel rapidly released the absorbed water, significantly increasing the water evaporation rate.

3. Electrocatalytic Water Splitting Performance

The LB5O3 fibers exhibited low overpotential and Tafel slope in the OER reaction, indicating high catalytic activity. Outdoor experiments further validated the practical application potential of the device in arid environments, demonstrating its ability to simultaneously generate hydrogen and oxygen with efficiency close to theoretical values.

Conclusions and Research Significance

The study successfully developed a portable device capable of capturing moisture from the atmosphere using high-entropy perovskite aerogels and driving water evaporation and electrocatalytic water splitting with solar energy, simultaneously generating clean water and green energy. This technology provides a sustainable solution for water and energy resources in arid and remote regions, offering significant scientific and practical value.

Research Highlights

  1. Exceptional Performance of High-Entropy Perovskite Fibers: Through the synergistic effect of multiple metals, the LB5O3 fibers exhibited high catalytic activity in the OER reaction.
  2. Efficient Moisture Absorption and Water Release of the Aerogel: The CA-LB5O3-LiCl aerogel efficiently absorbed moisture under low humidity conditions and rapidly released water under solar irradiation.
  3. Innovative Design of the Integrated Device: The device combines AWH, photothermal evaporation, and electrocatalytic water splitting technologies, enabling the simultaneous generation of water and energy.

This research not only provides a new technological pathway to address global water and energy shortages but also opens up new research directions for the application of high-entropy materials in energy conversion.